PCC MarchApril Final Draft

March / April 2021 

A Review of Pythium Diseases in Row Crops 

A New Generation of Precision Spray Technology 

Using N-Rich Reference Zones in Small Grains 

Plastic Mulches Reduce SWD in Raspberry 

An All New Daily Radio Show 

Available now on the MyAgLife App, Download Today 

Volume 6: Issue 2 

Photo courtesy S. Koike

www.afrikelp-usa.com 

A28236

4 

8 

12 

18 

24 

IN THIS ISSUE 

A New Generation 

of Precision Spray 

Technology 

Using N-Rich Reference 

Zones to Inform In-Season 

Nitrogen Fertilization 

Practices in California 

Small Grains 

A Review of Pythium 

Diseases in Row Crops 

Plastic Mulches Reduce 

Spotted-Wing Drosophila 

Infestation in Fall-Bearing 

Raspberry 

New Findings on Limb 

Dieback of Figs in 

California 

4 

PUBLISHER: Jason Scott 

Email: jason@jcsmarketinginc.com 

EDITOR: Marni Katz 

ASSOCIATE EDITOR: Cecilia Parsons 

Email: article@jcsmarketinginc.com 

PRODUCTION: design@jcsmarketinginc.com 

Phone: 559.352.4456 

Fax: 559.472.3113 

Web: www.progressivecrop.com 

CONTRIBUTING WRITERS & INDUSTRY SUPPORT 

Amaya Atucha 

University of Wisconsin, Madison 

Steve Booher 

Founder & CEO, Smart Guided® 

Systems, LLC 

Nick Clark 

UC Cooperative Extension 

Warren E. Clark 

Contributing Writer 

Surendra K. Dara 

UCCE Entomology and Biologicals 

Advisor 

Giuliano Galdi 


Tom Getts 


Christelle Guédot 


Steven Koike 

TriCal Diagnostics 

Michelle Leinfelder-Miles 


Sarah Light 


Mark Lundy 

Department of Plant Sciences, 

UC Davis 

Konrad Mathesius 


Hanna McIntosh 


Themis J. Michailides 


David Morgan 


Taylor Nelsen 

Department of Plant Sciences, 

UC Davis 

Jerome Pier Ph.D. 

CCA, PCA, Board Chairman, Western 

Region Certified Crop Advisors 

Zheng Wang 

UCCE Vegetable Crops Farm 

Advisor, Stanislaus County 

Heping Zhu 

Agricultural Engineer and Lead 

Scientist, USDA-ARS Application 

Technology Research Unit 

30 

36 

42 

46 

Enhancing Diamondback 

Moth Management with 

Mating Disruption 

Vegetable Growers 

Express Impressions, 

Concerns and Hope for 

Crop Biostimulants 

Life After Methyl Bromide 

in California Berries 

Understanding CCA 

Certification Exams 

12 

36 

UC COOPERATIVE EXTENSION 

ADVISORY BOARD 

Surendra Dara 

UCCE Entomology and 

Biologicals Advisor, San Luis 

Obispo and Santa Barbara 

Counties 

Kevin Day 

UCCE Pomology Farm Advisor, 

Tulare and Kings Counties 

Elizabeth Fichtner 

UCCE Farm Advisor, 

Tulare County 

Katherine Jarvis-Shean 

UCCE Orchard Systems Advisor, 

Sacramento, Solano and 

Yolo Counties 

Steven Koike 

Tri-Cal Diagnostics 

Jhalendra Rijal 

UCCE Integrated Pest 

Management Advisor, 

Stanislaus County 

Kris Tollerup 

UCCE Integrated Pest Management 

Advisor, Fresno, CA 

Mohammad Yaghmour 

UCCE Area Orchard Systems 

Advisor, Kern County 

The articles, research, industry updates, company profiles, and advertisements 

in this publication are the professional opinions of writers 

and advertisers. Progressive Crop Consultant does not assume any 

responsibility for the opinions given in the publication. 

March / April 2021 www.progressivecrop.com 3

A New Generation of 

Precision Spray Technology 

New retrofit kit creates automated universal intelligent 

spray control system for existing sprayers that could 

benefit growers and the environment. 

By HEPING ZHU | Agricultural Engineer and Lead Scientist, USDA-ARS Application Technology Research Unit 

and STEVE BOOHER | Founder & CEO, Smart Guided® Systems, LLC 

Fruit, nut, ornamental nursery, 

horticultural and greenhouse 

industries are among the fastest-growing 

enterprises in US agriculture. 

Application of pesticides 

and other production strategies have 

ensured their high-quality products 

meet stringent market requirements. 

However, low-efficiency, decades-old 

spray technologies are commonly 

used to treat these specialty crops and 

have caused an enormous amount of 

pesticide waste, additional costs in 

crop production and concerns around 

worker safety. The pesticide waste has 

also caused environmental contamination 

and ecosystem damage because 

pesticide sprays indiscriminately kill 

both pests and beneficial insects. Spray 

drift and off-target loss will likely 

remain a major problem as long as pesticides 

are applied using indiscriminate 

spray equipment. 

Need for Efficient Technologies 

Pesticide application is the most 

complicated operation in crop production 

because there are many variables 

affecting spray strategies and practices. 

In many cases, when decisions must 

be made to apply chemicals within a 

very narrow time window in response 

to escalating pest pressure, a simple 

“best guess” practice is often under 

vague labeling of pesticide rates to 

control pests that may result in excessive 

application of pesticides. 

Given constrained environments for 

specialty crop production, an ideal 

spray management program for pests 

and diseases should include improved 

delivery systems that are flexible for 

spraying the amount of chemicals 

to match tree structures instead of 

acreage base. Such spray application 

will also produce minimum spray drift 

and off-target loss of pesticide on the 

ground and in the air. 

To achieve this goal, a new automated 

universal intelligent spray control system 

was developed as a retrofit kit to 

attach on existing sprayers. With the 

intelligent control system, the conventional 

spraying systems can determine 

the presence, size, shape, and foliage 

density of target plants such as trees 

and grape vines, and then automatically 

apply the amount of pesticides 

as needed according to plant architectures 

in real time. With the control 

system, growers themselves can upgrade 

their own sprayers to precision 

sprayers with intelligent functions 

rather than buying new sprayers, and 

sprayer manufacturers do not need to 

change their current sprayer designs. 

The primary requirement for the 

upgrade action is to connect a variable-flowrate 

solenoid valve to each 

nozzle, and all other components are 

attached to the sprayer body without 

changing the sprayer structure. 

This new system is the product of a 

decade of research and development 

by engineers at USDA-ARS at Wooster, 

Ohio in collaboration with researchers 

at The Ohio State University, Oregon 

State University, University of Tennessee, 

Clemson University, Texas 

A&M University, Iowa State University, 

Washington State University, 

Penn State University, University of 

Queensland and USDA-ARS. 

Since 2013, the system has been tested 

as a retrofit on different types of the 

air-blast sprayers for pest control effectiveness, 

reliability and repeatability 

on real farm fields. Comparative field 

biological tests were also conducted 

to evaluate insect and disease control 

for the sprayers with and without the 

intelligent-decision control capabilities 

in commercial nurseries, apple 

orchards, peach orchards, pecan 

orchards, vineyards and small fruit 

productions as well as university research 

farms in Ohio, Oregon, Tennessee, 

South Carolina, Texas, California 

and Washington. 

These activities were voluntarily held 

by UCCE in Napa County and University 

of Queensland in Australia. 

System Features 

Spray deposition uniformity insidecanopies, 

chemical usage and off-target 

losses were investigated for the 

plants at different growth stages in 

ornamental nurseries, apple orchards, 

peach orchards and vineyards. Multiyear 

field tests have demonstrated the 

intelligent spray system is reliable and 

can reduce pesticide use in a range between 

30% and 90%, reduce airborne 

spray drift between 60% and 90%, 

4 Progressive Crop Consultant March / April 2021

Figure 1. Integration of universal intelligent spray control system as a retrofit kit 

into existing sprayers. 

All components of the smart sprayer retrofit kit are 

attached to the sprayer body without changing the 

sprayer structure, with the exception of connecting a 

variable-flowrate solenoid valve to each nozzle. 

and reduce spray loss to the ground 

between 40% and 80%, resulting in 

chemical savings in a range of $56 to 

$812 per acre annually. At the same 

time, the insect and disease control 

efficiencies are comparable or even 

better than standard sprayer practices. 

Because it uses less spray volume, it 

can spray more acres with the same 

amount of tank mixtures, thus reducing 

tank refilling times and reducing 

labor and fuel costs. 

As a result, Smart Guided Systems, 

LLC commercialized the intelligent 

spray system, and a commercial version 

of the product has been developed 

with joint efforts between USDA-ARS 

and Smart Guided Systems, LLC. The 

new control system (See Figure 1) 

includes a new laser sensor, an Android 

Samsung tablet, a GPS navigator, 

an automatic flow rate controller, air 

filtration unit, a toggle switch box and 

a universal mounting kit. 

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The laser sensor is mounted between 

the tractor and the sprayer to “see” 

plants on both sides of the sprayer. It 

releases 54,000 detection signals per 

second with a 270-degree and 164- 

ft radial detection range. The laser 

signals bounced back from the plant 

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Continued from Page 5 

canopies is used to determine the presence 

of a plant canopy and measure the 

canopy height, width, foliage density 

and canopy foliage volume (Figure 2). 

The GPS navigation device (or the radar 

speed sensor mounted at the bottom 

of the sprayer) measures sprayer travel 

speeds and location of each plant in the 

field. Based on the plant canopy foliage 

volume and the sprayer ground speed, 

the amount of spray for each nozzle 

is determined and then discharged 

to different parts of each plant in real 

time. Each nozzle is connected to a 10 

Hz pulse width modulation (PWM) solenoid 

valve, and the nozzle flow rates 

are controlled by manipulating the 

duty cycle of the PWM waveforms with 

the flow controller. The flow controller 

consists of microprocessors to generate 

flow rate commands for each nozzle 

to discharge variable spray rates. Field 

data collected and processed with the 

intelligent spray system are synchronized 

through the tablet WiFi to the 

cloud. 

The Android tablet provides the information 

for operators to communicate 

with the spray control system. The 

screen displays the sprayer travel speed, 

total discharged spray volume, spray 

width, and active nozzles. The operator 

can use the touch screen to modify 

the spray parameters as needed. The 

tablet allows the operator to activate 

the sprayer output on one or both sides 

in manual or automatic mode. All the 

electronic devices are powered by a 12V 

DC tractor battery. Another precaution 

includes the air filtration unit to discharge 

filtered air to prevent the laser 

sensor surface from getting dust and 

droplets. The toggle switches on the 

switch box are used to turn on/off main 

power, turn on/off the air filtration unit 

manually and override the automatic 

controller to activate nozzles as needed. 

Because sprayer travel speeds are automatically 

measured and included in the 

spray output control, applicators do not 

need to specify how fast they drive the 

tractor. However, travel speeds are not 

Figure 2. Laser sensor signals are used to measure canopy architecture and then manipulate 

individual nozzle flow rates as the function of the sectional canopy foliage volume and 

travel speed in real time. 

suggested to be higher than 5 MPH for 

orchard spray applications. 

Features in the commercial system also 

include tree counting, tree size, foliage 

density heat map comparison capability, 

liquid volume sprayed per plant, 

maps of sprayed plant locations, ability 

to turn nozzles on/off independently 

through the tablet screen, cloud sync 

feature, web portal for configuration 

settings and spray coverage report view, 

system log files, five different languages 

(English, Spanish, French, German and 

Italian), and options for choosing metric 

or imperial units. The commercial 

products have been used by growers in 

the US and other countries with crops 

including citrus, nursery, pecan, blueberry, 

peach, almond, apple and pear 

with pesticide usage reductions in the 

range between 30% to 85% depending 

on crop types and growth stages. John 

Deere also established an agreement 

with Smart Guided Systems to sell the 

commercial intelligent spray control 

system for use in high-value crop applications 

through their dealer network. 

The intelligent spray control system advances 

conventional standard pesticide 

application systems with the flexibility 

to spray specific positions on the plants. 

It reduces human involvement in 

decisions on how much spray volume 

is needed because the spray volume 

applied in the field is automatically 

controlled by the plant foliage volume 

instead of the antiquated gallons per 

acre. 

The conventional air-blast spray system 

has been used from generation to generation 

for almost 80 years because of 

its robustness. Growers have accumulated 

extensive experience on using it to 

control pests in accommodation with 

their own crops. After being retrofitted 

with the intelligent spray control 

system, the conventional sprayers are 

able to turn on and off each nozzle and 

will stop spraying non-target areas such 

as gaps between trees, on the ground 

and above trees while their capabilities 

of spray penetration, spray range 

and spray deposition quality on plants 

remain the same. This new generation 

of spray technology is anticipated to be 

a primary precision spray technology 

for future decades to save chemicals for 

growers and provide a sustainable and 

environmentally responsible approach 

to protecting crops. 

Comments about this article? We want 

to hear from you. Feel free to email us at 

article@jcsmarketinginc.com 


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Using N-Rich 

Reference Zones to 

Inform In-Season 

Nitrogen Fertilization 

Practices in California 

Small Grains 

By MICHELLE LEINFELDER-MILES | UC Cooperative Extension 

NICK CLARK | UC Cooperative Extension 

TAYLOR NELSEN | Department of Plant Sciences, UC Davis 

TOM GETTS | UC Cooperative Extension 

KONRAD MATHESIUS | UC Cooperative Extension 

SARAH LIGHT | UC Cooperative Extension 

GIULIANO GALDI | UC Cooperative Extension 

and MARK LUNDY | Department of Plant Sciences, UC Davis 

Over the last year, a team from 

UCCE has been working with 

California small grains growers 

on practices that can improve nitrogen 

(N) use efficiency. At demonstration 

sites, we have implemented practices 

that UC Grain Cropping Systems Specialist 

Mark Lundy has been investigating 

for several years, namely N-rich 

reference zones, a soil nitrate quick test, 

handheld reflectance devices and aerial 

imagery. We demonstrate how to use 

these tools to manage N fertilizers in 

small grain crops across variable soil 

and climatic conditions in the Sacramento 

Valley, Delta, San Joaquin Valley 

and Intermountain Region. 

The demonstrations are funded by the 

CDFA Fertilizer Research and Education 

Program and a USDA-NRCS 

California Conservation Innovation 

Grant. Our goal is to help growers and 

consultants learn and implement these 

practices to guide N fertilization in 

small grains, thereby increasing crop 

productivity and N use efficiency while 

reducing potential for N loss to the 

environment. 

What are “N-Rich 

Reference Zones”? 

Reference zones are most useful to 

growers who can apply the majority of 

their seasonal N budget during or after 

the tillering stage of growth. Previous 

work has shown that N fertilizer 

applied during the season−between the 

tillering and heading stages of small 

grain development−results in higher 

yields, higher protein and increased fertilizer 

use efficiency compared to preplant 

applications. The reference zone 

is a relatively small area within the field 

where extra N fertilizer is added at the 

beginning of the season. This extra fertilizer 

ensures that the reference zone 

will not be N-limited from planting 

until an in-season fertilizer decision is 

made. When a grower is determining 

whether and how much N fertilizer to 

add in-season, measurements from 

both the reference zone and the broader 

field are compared to understand 

whether the broader field is sufficient in 

plant-available N. 

Fertilizer N Rate and 

Field Variability 

Fertilizer N rate and field variability 

are two important considerations when 

creating N-rich reference zones. The 

amount of N to apply in the N-rich 

zone will depend on several factors 

such as yield goal, protein goal and 

when the expected in-season fertilizer 

application will take place. There 

should be sufficient N applied to the 

reference zone at planting to ensure 

that the plants in the zone are not limited 

by N at the stages of growth when 

the in-season fertilizer is applied. Table 

1 (see page 9) gives some examples of 

how much N fertilizer to apply to the 

N-rich zone for a range of potential 

yields. 

It is important to establish the N-rich 

zones in representative parts of the 

field. Areas of the field that are unique 

(i.e. low areas, high areas, gravel 

strips, etc.) should be avoided. It is 

also important that the zones capture 

field variability. If certain areas have 

distinct soil types or known patterns 

of yield or management differences, a 

grower should establish multiple zones 

to account for these sources of spatial 

variability if they represent large 

areas in the field. Soil maps (available 

from casoilresource.lawr.ucdavis.edu/ 

soilweb-apps/) and historical aerial 

imagery can often help in identifying 

field patterns and good location(s) for 

reference zones. 

How and When to Apply the 

N-Rich Zone Fertilizer 

A grower can establish N-rich zones 

during the pre-plant fertilizer application. 

For example, a grower may apply 

50 pounds N per acre across the field 

and then make another pass or two in 

the zone to apply an additional 50 to 

100 pounds N per acre (depending on 

what the grower calculates is necessary, 

as described above.) This method might 

be most easily adopted by growers. We 

have observed, however, that if the 

fertilizer is placed too deep in the soil 

profile, the N may not be readily available 

to the seedling crop early in the 

season because it is below the root zone. 

Therefore, N-rich zones established by 

this method may not provide a reliable 

early-season point of comparison. 

Instead, we have found that broadcasting 

urea is the most effective way to 

establish N-rich zones. At our demonstration 

sites, we broadcasted urea after 

tillage or shortly after planting, but 

always ahead of a storm or irrigation 

event that could incorporate the fertilizer. 

Orienting the zones perpendicular 

to the rows or tractor passes also helps 


Average Yield 

(lb/ac, 12% protein) 

Crop stage of 

assessment/application 

N rate (lb/ac) needed in 

N-rich zone 

3000 tillering 

65 

5000 

7000 

3000 

5000 

7000 

tillering 

tillering 

flag leaf 

flag leaf 

flag leaf 

110 

150 

120 

200 

275 

Table 1. Approximate N fertilizer application rates suggested for use in N-rich reference zones based on a range of average 

yields and two stages of crop growth. Suggested rates ensure that crops within the reference zone are not N-limited when an 

in-season fertilizer application decision is being made at the crop stage indicated. 

to capture field variability. When the 

zones are too narrow and run in the 

same direction as the field work, it can 

be hard to differentiate between a field 

pattern associated with equipment 

passes and a N effect, particularly early 

in the season. 

Monitoring the Field 

Once the crop begins to grow, the field 

should be monitored periodically to 

assess whether the crop is likely to 

respond to a N fertilizer application. A 

combination of the soil nitrate quick 

test (SNQT) and plant reflectance measurements 

taken from both the N-rich 

zones and the broader field can indicate 

when a top-dress fertilizer application 

may be beneficial. The soil nitrate quick 

test and plant reflectance measurements 

complement other important 

information like current crop growth 

stage, crop yield and protein goals, 

and local weather records to inform a 

site-specific N fertilizer recommendation. 

The SNQT is a simple and low-cost test 

that provides a ballpark estimate of the 

soil nitrate-N concentration in the root 

zone. Nitrate is a highly plant-available 


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Figure 1. The GreenSeeker held above a recently headed small grain and 

displaying the NDVI value. Values range from 0 to 1 (i.e. less-green to very 

green plants). 

Figure 3. Small grain leaf inserted in the sampling area of the 

at LEAF showing a chlorophyll reading in the lower right corner 

of the display while the user’s back shades the device. 

Figure 2. A field in Solano County where three N-rich reference zones are visible at tillering 

using NDRE captured via drone (left), but not visible to the naked eye (right). 


form of N. Using the SNQT when N 

fertilizer decisions are being made will 

help to narrow a range of fertilizer rates 

appropriate for that field. More information 

on using the SNQT in small 

grains, including a sample protocol 

and demonstration video, is available at 

smallgrains.ucanr.edu/Nutrient_Management/snqt/. 

Over the past several 

years, UCCE agronomists have developed 

a strong relationship between the 

value measured using the SNQT and an 

estimate of fertilizer N equivalence. 

Crop reflectance can be measured 

using a number of tools, including 

handheld devices, drones and satellite 

imagery. Common indices that 

result from measurements of canopy 

reflectance are normalized difference 

vegetation index (NDVI) and normalized 

difference red edge index (NDRE). 

These indices represent measurements 

of light reflected from the crop canopy 

at key wavelengths indicative of plant 

vigor. Relative differences in vigor 

among plants in the same field can be 

captured by comparing canopy reflectance 

measurements like NDVI and 

NDRE. We have been using handheld 

devices, drones and satellite imagery 

at our demonstration sites to compare 

crop reflectance values in the N-rich 

zones and the broader field. 

One of the tools we are using is the 

GreenSeeker by Trimble Agriculture. 

This is a hand-held NDVI meter (See 

Figure 1) that emits light and detects 

how much is reflected from the crop 

canopy in the red and infrared wavelengths. 

The GreenSeeker’s canopy 

measurement indicates how well the 

plants are growing and covering the 

soil with greenness. This information 

about vigor is important early in the 

crop’s growth because it indicates the 

ability of plants to support grain production 

and yield potential. 

We are obtaining similar information 

as from the GreenSeeker by measuring 

NDRE with a five-band multispectral 

camera (MicaSense RedEdge-MX) 

mounted on a drone (DJI Matrice 

M200 V2). NDRE is similar to NDVI 

but replaces the reflectance from the 

red wavelength with reflectance from 

the red edge wavelength. Because the 

drone is able to capture data from hundreds 

of feet above the ground, it allows 

us to measure a large area quickly and 

under conditions when entering the 

field is not possible. Figure 2 depicts 

side-by-side images from a field in 

Solano County where N-rich reference 

zones were implemented during the 

2019-20 season. 

Another device we are using to monitor 

plant N is the atLEAF CHL by FT 

Green LLC, which is a chlorophyll 

meter that measures light absorbed 

by a single leaf (Figure 3). Like 

the GreenSeeker, it also emits and 

detects light. The atLEAF CHL, however, 

measures how much light passes 

through a single leaf instead of measuring 

reflected light. This information 

becomes increasingly valuable as an 

indicator of whether or not the crop 

has sufficient N as it begins heading out 

and filling grain. 

Step-by-step instructions for using 

both the GreenSeeker and atLEAF 

CHL in small grains are available at 

ucanr.edu/blogs/blogcore/postdetail. 

cfm?postnum=42903. 

Since plant N is strongly related to 

plant greenness and chlorophyll 

content, measurements of NDVI, 


NDRE and leaf chlorophyll can serve 

as proxies for relative plant N status 

within a field. Many factors can affect 

absolute greenness or chlorophyll values, 

including variety, crop injury and 

environmental factors. Because of this, 

it is important to remember that the 

absolute values given by these devices 

are only meaningful when compared to 

a reference zone like the N-rich zone. 

What do the Readings Mean? 

Plant reflectance and transmittance 

measurements are best interpreted 

by expressing values measured in the 

broader field relative to the N-rich reference 

zones, according to the following 

equation: 

Relative value= (Production area value)/(N-rich 

zone value) 

The relative value is sometimes referred 

to as a Sufficiency Index (SI) and 

will usually result in a decimal value 

between 0 and 1. When the SI is below 

a certain threshold, it indicates that 

the production area is experiencing 

detectable N deficiency relative to the 

N-rich zone. Table 2 shows SI ranges 

for proximal and remotely-sensed data 

and the associated plant N status. 

When it comes to deciding on N fertilization 

in California small grains, a 

N fertilizer response is almost certain 

when plant N status is “Highly Deficient”, 

very likely when the status is 

“Deficient” and uncertain when the 

status is “Sufficient”. The SNQT supplements 

the plant measurements with 

information about the current nitrate 

concentration in the root zone. 

If a grower decides that a N fertilizer 

application is warranted based on the 

combination of plant and soil measurements, 

the next step is to figure 

how much N is necessary. This can be 

determined using a crop growth and 

N uptake model in conjunction with 

yield and protein goals. As part of our 

larger demonstration project, we will 

be releasing an online decision support 

tool in 2021 that integrates these 

components and provides customized 

predictions of crop response to in-season 

N fertilizer. 

SI Value Range 

> 0.95 High 

0.95 – 0.80 

< 0.80 

SI Category 

Medium 

Low 

Plant N Status 

Sufficient 

Deficient 

Highly Deficient 

Table 2. Sufficiency Index (SI) values and associated plant N sufficiency status, calculated 

as the production area value divided by the N-rich zone value. 

Your irrigation 

strategy in focus 

CERESIMAGING.NET/PROGRESSIVECROP 

Summary 

California farmers are under pressure 

to increase N use efficiency and 

reduce the potential for N loss to the 

environment. N-rich reference zones 

are a tool that can assist in these goals 

while considering and managing the 

risk of reduced yields. By implementing 

N-rich reference zones, using a suite 

of tools to monitor them during the 

season and comparing results to the 

broader field, a grower gets real-time 

knowledge to inform N fertilizer management 

in small grains. The information 

gained from implementing N-rich 

reference zones can help growers make 

fertilizer applications when increased 

yield and/or protein benefits are likely 

and avoid them when they are not. 

These improvements in N fertilizer 

decision-making can yield better economic 

and environmental outcomes in 

California small grain systems. 




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A REVIEW OF PYTHIUM 

DISEASES IN ROW CROPS 

Soilborne Organism 

is Known for Causing 

Seedling Diseases and 

Other Issues 

By STEVEN KOIKE | TriCal Diagnostics 

Large, established cauliflower plants can still become 

infected with Pythium (left), resulting in loss of roots, 

severe stunting and yield loss (all photos courtesy S. 

Koike.) 

It is highly likely that growers, PCAs 

and other field professionals are 

familiar with the word “Pythium”. 

Pythium is the name of a soilborne, 

fungus-like organism that is notorious 

for primarily causing seedling diseases. 

Pythium is notable because many row 

crops are susceptible to it, the pathogen 

is very widely distributed and occurs in 

most cropped ground, and despite the 

use of IPM tools and strategies, Pythium 

problems can still show up in row 

crop production systems. 

What is Pythium? 

Pythium is a fungus-like organism. Previously 

considered to be a true fungus, 

molecular studies in recent years indicate 

that Pythium—as well as closely related 

organisms like Phytophthora and 

downy mildew—is more closely related 

to brown algae and diatoms. Formally, 

therefore, Pythium species are no longer 

part of the fungal taxonomic group but 

are classified in the kingdom Chromista, 

or Stramenopila. The Pythium 

genus contains over 200 species, most 

of which are not plant pathogens. There 

are Pythium species that are pathogens 

of animals (some of which can infect 

humans), and many species are saprophytes 

and only grow on dead 

and decaying organic material. 

Pythium species are mostly 

found in soil environments 

but are also present in aquatic 

habitats. 

Plant pathogenic Pythium 

species are well equipped to 

cause problems on row crops. 

Most of these species form 

resilient, thick-walled sexual 

spores (oospores) that can 

withstand periods of unfavorable 

dry and warm conditions. 

These structures enable 

Pythium to persist in the soil for a long 

time. When favorable soil conditions 

are present, mostly in the form of abundant 

soil water, these Pythium organisms 

either produce hyphae that grow 

toward the roots or swimming spores 

(zoospores) that move through the soil 

water in search of susceptible plant 

tissues. Another feature that makes 

Pythium problematic for growers is the 

extremely fast growth rate of these organisms. 

Given suitable soil conditions, 

Pythium pathogens can rapidly grow 

from seed-to-seed, seedling-to-seedling 

The primary symptom of Pythium diseases is the dark 

discoloration and decay of roots, pictured here on 

lettuce. 

and root-to-root. 

Diverse Pythium Diseases 

In contrast to many plant pathogens, 

Pythium causes several different types 

of problems on crops (Table 1, see page 

14). First, Pythium is a seed pathogen. 

Once placed in the ground, seed can 

be exposed to Pythium that is residing 

in the soil. If conditions are favorable 

for the pathogen, Pythium can invade 

and colonize the seed, causing it to 

rot before it can germinate. If the seed 

germinates, Pythium can cause a decay 



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PYTHIUM DISEASE CATEGORY 

Seed decay 

Pre-emergent 

damping-off 

Post-emergent 

damping-off 

Root and crown rot of 

young plants 

Root rot of mature 

plants 

Foliar blight 

Vegetable soft rot 

TARGETED PLANT TISSUE 

Seed planted in the ground is invaded 

and rotted before the seed germinates. 

Seed germinates; root and shoot are 

infected and killed before seedling 

shoot emerges above the ground. 

Seed germinates; root and shoot are 

infected but seedling shoot is able to 

emerge above ground before collapsing 

and dying. 

Young plants are healthy while 

germinating and emerging; after 

plant establishment, roots or 

crowns become infected. 

Roots of mature plants can become 

infected later in crop development. This 

results in “root pruning” and subsequent 

reduction in growth, vigor, and yield. 

Above ground leaves, stems, shoots 

become diseased when the pathogen 

is splashed up onto foliage. 

Fleshy vegetables such as cucurbit 

fruits, sweet potato roots, and 

potato tubers develop soft decays. 

Table 1. Categories of Pythium diseases of row crops 


of the roots and shoots that just grew out of the seed. This early 

disease stage is often called damping-off. Damping-off is further 

divided into two phases. If the newly germinated seedling is 

infected so early and so severely that it dies before being able to 

break through the soil surface, this situation is called pre-emergent 

damping-off. However, post-emergent damping-off occurs 

if the diseased seedling is strong enough to emerge above the soil 

surface, only to succumb and collapse shortly afterwards. Collectively, 

seed decay, pre-emergent damping-off, and post-emergent 

damping-off can result in loss of plants very early in the production 

cycle, causing stand loss in the field. 

Healthy seedlings that escape death at the seed and newly germinated 

stages remain vulnerable to this pathogen; established 

seedlings can still be infected and become stunted and die due to 

diseased roots and crowns. Older, established plants have escaped 

the damping-off phase that kills seedlings but can be subject to 

infections that prune back the roots, leading to reduced plant 

vigor and yield. For example, Pythium can cause late infections 

in cauliflower and result in weakened roots and poorly yielding 

plants. This soilborne pathogen can even cause a foliar blight of 

leaves and shoots, though this type of disease is not very common. 

Bits of soil carrying Pythium can be splashed or moved 

up onto foliage and cause blights on crops such as spinach and 

bean. Finally, the fleshy parts of some vegetable crops are subject 

to Pythium pathogens. If in contact with infested soil, cucurbit 


Pythium pathogens form thick-walled oospores that enable the 

pathogen to survive in soil for prolonged periods. 

When sufficient soil water is present, Pythium forms swimming 

spores that are released and search for host roots. Pictured here is 

a cluster of zoospores just prior to release. 

fruits, sweet potato storage roots and 

potato tubers can develop a soft, watery 

rot that will result in a non-marketable 

commodity. 

Of the hundreds of Pythium species 

worldwide, relatively few species infect 

row crops. These plant pathogens can 

be conveniently placed into two categories. 

One group consists of Pythium 

species that have a relatively narrow 

host range and infect only a few crops, 

with those few crops tending to mostly 

be within a particular plant family. 

Examples are Pythium mastophorum, 

which primarily infects celery and 

parsley (Apiaceae family), and Pythium 

uncinulatum, which reportedly only 

causes significant disease on lettuce 

(Table 2, see page 16). The second 

group contains Pythium organisms that 

have very large host ranges. The two 

main species, P. aphanidermatum and 

P. ultimum, both infect scores of plants, 

including dozens of vegetable and row 

crops. 


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Pythium species 

P. aphanidermatum 

P. irregulare 

P. mastophorum 

P. polymastum 

P. sulcatum 

P. ultimum 

P. uncinulatum 

P. violae 

Reported row crop hosts 

bean, beet, cabbage, carrot, cauliflower, cucumber, eggplant, lettuce, melon, onion, parsley, pea, pepper, 

potato, radish, spinach, sweet potato, tomato, watermelon 

asparagus, basil, bean, beet, Brussels sprouts, cabbage, carrot, cauliflower, celery, cilantro, cucumber, eggplant, 

endive, lettuce, melon, onion, parsley, pea, pepper, potato, radish, spinach, sweet potato, tomato, watermelon 

celery, parsley 

broccoli, cabbage, cauliflower 

carrot( infects other crops but causes few symptoms) 

bean, beet, Brussels sprouts, cabbage, carrot, cauliflower, celery, cilantro, cucumber, eggplant, endive, leek, 

lettuce, melon, onion, pea, pepper, potato, radish, spinach, sweet potato, tomato, watermelon 

lettuce 

carrot( infects other crops but causes few symptoms) 

Table 2. Examples of Pythium pathogens with broad vs. narrow host ranges 

"Fertigation 

delivers fertilizer 

to active 

roots. As long as 

irrigation is 

managed to deliver 

only needed 

water, fertigation 

can be a 

highly efficient 

method of 

fertilization." 


Disease Development 

Development of Pythium diseases is 

straightforward. Initial inoculum is 

almost always linked with infested field 

soils and associated soil water. Pythium 

is a soilborne pathogen that resides in 

the soil primarily as dormant resting 

structures. Pythium inoculum is not 

seedborne or airborne. For Pythium 

to become active, grow, and produce 

those swimming zoospores, the soil 

must be wet for prolonged periods. 

Once susceptible 

seed, seedlings, 

and other plant 

parts are in 

close contact 

with Pythium 

inoculum, 

infection can take 

place and disease 

will be initiated. 

If wet soil 

conditions persist 

and temperatures 

are optimum 

for the pathogen, 

disease losses can 

be significant. 

Diagnostic Considerations 

Pythium is not the only soilborne 

pathogen that causes seedling damping-off 

and root rots of row crops. On 

spinach, damping-off and root rot can 

be caused by both Pythium and Fusarium; 

visually, one cannot distinguish 

between the symptoms caused by these 

two pathogens. Pythium and Phytophthora 

pathogens both cause dark, discolored 

roots of lettuce and cannot be 

differentiated in the field. Cauliflower 

transplants are susceptible to both Pythium 

and Rhizoctonia pathogens, both 

of which caused the roots to become 

Pythium plant pathogens can grow very rapidly. Pictured here are 

three-day-old cultures of Pythium, Phytophthora, Fusarium and 

Verticillium. The diameter of the petri dish is 85 mm. 


NAVEL ORANGEWORM MANAGEMENT 

discolored. Precise and accurate diagnosis 

of Pythium diseases will therefore 

require lab-based tests and assays. 

Managing Pythium 

Controlling diseases caused by Pythium 

requires the implementation of IPM 

practices. 

Site selection: Choose to plant in fields 

that do not have a history of Pythium 

problems and have well-draining soils. 

Crop rotation: If Pythium is an issue, 

avoid planting the same susceptible 

crop in the infested field. Rotate to 

crops that are not known to be susceptible 

to the Pythium species present at 

that location. However, remember that 

some Pythium species have very broad 

host ranges (Table 2). 

Irrigation management: Because the 

Pythium pathogen is so strongly dependent 

on wet soil conditions, carefully 

schedule and limit irrigations to prevent 

overwatered, saturated soils. 

Time of planting: In some cases, moving 

the planting date to a different time 

of year may help reduce losses to Pythium. 

For example, depending on the 

Pythium species of concern, planting 

the crop in the warmer, drier summer 

may be preferred to seeding the crop in 

the cooler, wetter spring. 

Fungicides: Plant seed treated with a 

fungicide that is active against Pythium. 

Note that the fungicides used to control 

Rhizoctonia or Fusarium have no effect 

on Pythium. For some crops, applying 

fungicides to the emergent crop may 

provide additional protection. The repeated 

use of products having the same 

mode of action can result in Pythium 

isolates that are insensitive (=resistant) 

to those products; therefore, IPM strategies 

will require that thought be given 

to deploying different fungicides. 

Resistant or tolerant cultivars: Unfortunately, 

there do not appear to be any 

row crop cultivars that have genetic 

resistance to Pythium. 




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Plastic Mulches Reduce 

Spotted-Wing Drosophila Infestation 

in Fall-Bearing Raspberry 

By HANNA MCINTOSH | University of Wisconsin, Madison 

CHRISTELLE GUÉDOT | University of Wisconsin, Madison 

AMAYA ATUCHA | University of Wisconsin, Madison 

Spotted-wing drosophila (SWD), 

Drosophila suzukii, is an invasive 

vinegar fly and a major pest of softskinned 

fruit crops. The fly was first 

detected in the continental U.S. in 2008 1 

and has quickly spread from its native 

range in Eastern Asia throughout the 

U.S. and into most major fruit-producing 

regions of the world 2 . For smallscale 

fruit growers, damage from this 

pest substantially reduces the yield of 

marketable fruit, making susceptible 

crops challenging to grow economically 

and sustainably 3,4 . For large-scale 

growers, the presence of SWD can lead 

to complete crop loss due to processors’ 

zero-tolerance policies for insect 

infestation 5 . 

Spotted-wing drosophila life cycle (courtesy 

Jana Lee, USDA-ARS.) 

Biology 

Vinegar flies typically lay their eggs in 

damaged or rotting fruit, but female 

SWD have a highly serrated ovipositor 

that allows them to saw through the 

skin of undamaged, ripening fruit 6,7 , 

which makes SWD an especially detrimental 

pest. Larvae emerge inside of 

and feed on the fruit, making it mushy 

and unmarketable. Recent research 

showed that around 80% of larvae drop 

from the fruit to pupate in the top layer 

of soil and that they are more likely to 

drop from the fruit if the fruit is overcrowded 

8,9 . Larvae and pupae can also 

reach the ground when damaged fruit 

becomes mushy and falls to the ground. 

SWD has a quick generation 

time, with many generations 

per year in most regions. The fly 

develops fastest in temperatures 

between 68 to 83 degrees F, but 

is unable to develop at temperatures 

above about 87 degrees 

F 10,11 . In temperate regions like 

the Upper Midwest or Pacific 

Northwest, SWD populations 

are highest during summer 

months. In hotter regions 

like California or Florida, fly 

populations are highest in the 

spring and fall and are much 

lower during their hot and dry 

summer months 12 . 

SWD thrives in high humidity, 

developing fastest around 94% 

humidity 13 . Researchers found 

that females laid more eggs in 

the inner canopy of blackberry and 

blueberry plants, likely because the 

environment is more humid, cooler 

and darker 14,15 . 

Fruit crops that are the most susceptible 

to SWD include raspberries, blackberries, 

blueberries, strawberries, sweet 

and tart cherries, and some cultivars 

of wine grapes 16-18 . However, SWD can 

survive on alternative hosts like wild 

blackberries and apples, buckthorn and 

honeysuckle. It remains largely unknown 

how SWD survive in the winter 

and spring before fruit is available in 

the landscape and on farms, but one 

study found that SWD can develop on 

non-fruit hosts like mushrooms and 

bird manure 19 . 

Traditional Management 

Pest pressure from SWD is often very 

high due to the fly’s fast development 

time, optimal development conditions 

in the summer and high availability 

of host plants and food in the agroecosystem. 

Management relies heavily 

on chemical control in organic and 

conventional systems, which is costly 

to growers. In California, chemical 

controls for SWD cost around $470/ 

acre for conventional and $1,210/acre 

for organic growers 3 . 

Only a few insecticides approved for 

use in organic systems are effective 

at controlling SWD, limiting organic 

growers’ options for control 20 . Unfortunately, 

recent reports show evidence 

of insecticide resistance developing 


(Left) Spotted-wing drosophila adult female and male on a raspberry. Male flies are easy to identify by the large black 

spots on their wings. (Right) Spotted-wing drosophila females have a serrated ovipositor that allows them to lay eggs in 

undamaged, ripening fruit (photos courtesy Agri-Mag and Chris Thomas.) 

for some active ingredients in some 

regions, including spinosad (the main 

insecticide used to control SWD in 

organic systems) 21,22 . 

Cultural practices can help reduce the 

fly’s population and are often used in 

tandem with chemical controls. Such 

practices include harvesting fruit 

promptly (every one to two days), frequent 

field sanitation, burial or composting 

of infested fruit and exclusion 

netting 23,24 . However, these methods are 

labor-intensive and expensive. 

Since SWD is sensitive to temperature 

and humidity, cultural practices that 

modify the crop canopy microclimate 

have the potential to reduce infestation 

by deterring adults from laying eggs or 

disrupting larval development inside of 

fruit. Management strategies for SWD 

typically target adult flies in the canopy, 

but since the majority of SWD larvae 

fall to the ground before pupation, 

ground-based cultural management 

practices could also be important for 

reducing populations. 

Growers have used plastic mulches 

since the 1960s to modify the microclimate 

in fruit and vegetable agroecosystems. 

Plastic mulches are commonly 

used for weed control, promoting 

earlier ripening, improving fruit 

quality or color and increasing yield 25,26 . 

Different colors of plastic mulches have 

also been shown to successfully control 

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insect pests including aphids, whiteflies, 

Asian citrus psyllid and Mexican bean 

beetles 27-30 . 

Plastic Mulches for SWD 

Based on the extensive body of literature 

reporting that plastic mulches can 

modify the crop microclimate, control 

some insect pests and provide other 

horticultural benefits, we tested the impact 

of three colors of plastic mulches 

on SWD adult and larval populations. 

Our study was conducted in 2019 and 

2020 on a small fruit and vegetable 

farm in South Central Wisconsin in 

fall-bearing raspberries. 

In this study, we tested black and whiteon-black 

biodegradable plastic mulches 

(Organix Solutions AG film), metallic 

polyethylene mulch (Imaflex SHINE N’ 

RIPE) and a grower-standard control 

where grass filled in the space between 

the alleyway and the raspberry plants. 

We assessed the three mulches’ impact 

on SWD adult and larval populations 

in fall-bearing raspberry. 

We laid the mulches by hand when the 

raspberry canes were just emerging 

from the soil in late April. We laid two 

mulch strips (25 feet long by 2.3 feet 

wide) along each side of the row, leaving 

a six-inch gap between the strips 

for the canes to grow. The edges of the 

mulches were secured with biodegradable 

sod stakes. All four treatments 

were randomly distributed in each of 

four rows of fall-bearing raspberries 

(cultivars “Polana” and “Caroline”), 

totaling 16 plots. 

Starting when the first flies were detected 

in June, we measured the adult SWD 

populations passively using clear sticky 

cards placed in the fruiting zone, which 

were replaced weekly to estimate fly 

populations by week. 

Larval infestation of fruit was 

evaluated by counting the number 

of larvae using the salt float method 

31 . The evaluations were done two 

to four times per month starting in 

August. 

Adult and larval populations were 

measured throughout the season 

until adult populations reached zero, 

usually in mid-October. 

We also did a preliminary experiment 

to test whether plastic mulches 

could kill larvae that fell onto the 

mulch surface. We put lab-reared 

larvae into ‘corrals’ made from 

plastic sandwich containers and 

recorded their mortality and movement 

over three hours. 

Population Reductions 

In both years of our study, we found 

significantly lower SWD populations 

above all three plastic mulches 

compared to the control plots. Over 

the two-year period, the black and 

metallic mulches reduced the adult 

population of SWD by 51% and the 

white mulch reduced flies by 42% 

compared to the control. 

Experimental plots of plastic mulches in fall-bearing raspberries in Wisconsin (photo by H. 

McIntosh.) 

Interestingly, the plastic mulches 

only reduced female fly populations 

and did not impact the number 

of male flies caught on the sticky 

cards. With fewer female flies in the 

canopy above the plastic mulches, 

it was unsurprising that we also 

found fewer larvae infesting the 

fruit in the mulched plots. Over the 

two-year study, the black mulch 


decreased the number of larvae in fruit by 72%, the 

metallic mulch by 61%, and the white mulch by 52% 

compared to the control. 

Plastic mulches may be more effective than other 

types of mulches tested for managing SWD. In our 

study, we recorded the lowest adult fly populations 

and larval infestation of fruit above the black plastic 

mulch. A 2019 study tested black fabric weedmat as 

a cultural control for SWD in blueberry in several 

states and found no effect of the weedmat on SWD 

infestation of blueberries 32 . It is possible that some 

quality of the plastic mulch material (such as reflectivity 

or lack of permeability) makes it more deterrent 

to SWD than the weedmat. 

In our preliminary experiment, larvae placed on the 

plastic mulches died quickly. Larvae on the black 

mulch died in less than one hour, and larvae on the 

white and metallic mulches died in less than three 

hours. We recorded high surface temperatures on 

the mulches, with all mulches heating up above 87 

degrees F (SWD’s threshold for development) for two 

to four hours each day. On hot days, the black mulch 

got above 150 degrees F. 

When placed on the mulch, we observed larvae 

struggling to crawl and visibly desiccating within 

minutes, making it unlikely that larvae could crawl 

off the mulch into the safety of the soil. We will 

collect more data in summer 2021 to confirm these 

promising results. 

The results of our study provide evidence that black, 

white and metallic plastic mulches can reduce SWD 

adult and larval populations in fall-bearing raspberry 

in the Upper Midwest, showing promise for 

use of plastic mulches in sustainable pest management. 

Combining plastic mulches with other cultural 

practices including short harvest intervals (every 

one to two days) and frequent field sanitation could 

have an additive effect on reducing SWD populations, 

potentially reducing the need for chemical 

controls in conventional and organic cropping 

systems. 

Next Steps 

Although the use of plastic mulches reduces SWD 

populations in the canopy of raspberry plants, the 

specific mechanisms causing this reduction are still 

unknown. We are still investigating how canopy 

light conditions, temperature and humidity are 

influenced by the plastic mulches and whether 

these factors can explain the reduction in SWD 

populations we measured. 


‘Corrals’ made from plastic sandwich containers used to test mortality 

of larvae on the mulch surface (photo by H. McIntosh.) 

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In the next two years of this project, 

we will conduct field experiments to 

determine whether the three plastic 

mulches we tested influence beneficial 

insects, including pollinators, and 

how the mulches impact soil health, 

raspberry plant growth, fruit quality 

and yield in Wisconsin’s climate. 

Testing these mulches in other regions 

and fruit crops is warranted to 

determine if the reduction of SWD is 

maintained in different climates and 

other susceptible crops. Overall, plastic 

mulches are a promising new tool for 

more sustainable management of SWD 

in raspberry in the Upper Midwest. 

References 

1. Hauser, M. A historic account of the invasion of 

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) 

in the continental United States, with 

remarks on their identification. Pest Manag. Sci. 

2011, 67, 1352–1357, doi:10.1002/ps.2265. 

2. CABI Drosophila suzukii (spotted wing drosophila); 

2016; 

3. Farnsworth, D.; Hamby, K.A.; Bolda, M.; Goodhue, 

R.E.; Williams, J.C.; Zalom, F.G. Economic 

analysis of revenue losses and control costs associated 

with the spotted wing drosophila, Drosophila 

suzukii (Matsumura), in the California raspberry 

industry. Pest Manag. Sci. 2017, 73, 1083–1090, 

doi:10.1002/ps.4497. 

4. DiGiacomo, G.; Hadrich, J.; Hutchison, W.D.; 

Peterson, H.; Rogers, M. Economic Impact of 

Spotted Wing Drosophila (Diptera: Drosophilidae) 

Yield Loss on Minnesota Raspberry Farms: 

A Grower Survey. J. Integr. Pest Manag. 2019, 10, 

doi:10.1093/jipm/pmz006. 

5. Bruck, D.J.; Bolda, M.; Tanigoshi, L.; Klick, J.; 

Kleiber, J.; Defrancesco, J.; Gerdeman, B.; Spitler, 

H. Laboratory and field comparisons of insecticides 

to reduce infestation of Drosophila suzukii in 

berry crops. Pest Manag. Sci. 2011, 67, 1375–1385, 

doi:10.1002/ps.2242. 

6. Kanzawa, T. Studies on Drosophila suzukii Mats. 

J. Plant Prot. 1939, 23, 66–70, 127–132, 183–191. 

7. Walsh, D.B.; Bolda, M.P.; Goodhue, R.E.; Dreves, 

A.J.; Lee, J.; Bruck, D.J.; Walton, V.M.; O’Neal, S.D.; 

Zalom, F.G. Drosophila suzukii (Diptera: Drosophilidae): 

Invasive Pest of Ripening Soft Fruit 

Expanding its Geographic Range and Damage 

Potential. J. Integr. Pest Manag. 2011, 2, G1–G7, 

doi:10.1603/ipm10010. 

' 

Management strategies for SWD typically target adult flies in the 

canopy, but since the majority of SWD larvae fall to the ground 

before pupation, ground-based cultural management practices 

could also be important for reducing populations. 

8. Woltz, J.M.; Lee, J.C. Pupation behavior 

and larval and pupal biocontrol of Drosophila 

suzukii in the field. Biol. Control 2017, 110, 62–69, 

doi:10.1016/j.biocontrol.2017.04.007. 

9. Bezerra Da Silva, C.S.; Park, K.R.; Blood, R.A.; 

Walton, V.M. Intraspecific Competition Affects 

the Pupation Behavior of Spotted-Wing Drosophila 

(Drosophila suzukii). Sci. Rep. 2019, 9, 7775, 

doi:10.1038/s41598-019-44248-6. 

10. Ryan, G.D.; Emiljanowicz, L.; Wilkinson, F.; 

Kornya, M.; Newman, J.A. Thermal tolerances of 

the spotted-wing drosophila drosophila suzukii 

(Diptera: Drosophilidae). J. Econ. Entomol. 2016, 

109, 746–752, doi:10.1093/jee/tow006. 

11. Hamby, K.A.; E. Bellamy, D.; Chiu, J.C.; Lee, 

J.C.; Walton, V.M.; Wiman, N.G.; York, R.M.; 

Biondi, A. Biotic and abiotic factors impacting development, 

behavior, phenology, and reproductive 

biology of Drosophila suzukii. J. Pest Sci. (2004). 

2016, 89, 605–619. 

12. Wang, X.G.; Stewart, T.J.; Biondi, A.; Chavez, 

B.A.; Ingels, C.; Caprile, J.; Grant, J.A.; Walton, 

V.M.; Daane, K.M. Population dynamics and ecology 

of Drosophila suzukii in Central California. 

J. Pest Sci. (2004). 2016, 89, 701–712, doi:10.1007/ 

s10340-016-0747-6. 

13. Tochen, S.; Woltz, J.M.; Dalton, D.T.; Lee, J.C.; 

Wiman, N.G.; Walton, V.M. Humidity affects populations 

of Drosophila suzukii (Diptera: Drosophilidae) 

in blueberry. J. Appl. Entomol. 2016, 140, 

47–57, doi:10.1111/jen.12247. 

14. Diepenbrock, L.M.; Burrack, H.J. Variation 

of within-crop microhabitat use by Drosophila 

suzukii (Diptera: Drosophilidae) in blackberry. J. 

Appl. Entomol. 2017, 141, 1–7, doi:10.1111/jen.12335. 

15. Evans, R.K.; Toews, M.D.; Sial, A.A. Diel periodicity 

of Drosophila suzukii (Diptera: Drosophilidae) 

under field conditions. PLoS One 2017, 12, 

doi:10.1371/journal.pone.0171718. 

16. Lee, J.C.; Bruck, D.J.; Curry, H.; Edwards, D.; 

Haviland, D.R.; Van Steenwyk, R.A.; Yorgey, B.M. 

The susceptibility of small fruits and cherries to 

the spotted-wing drosophila, Drosophila suzukii. 

Pest Manag. Sci. 2011, 67, 1358–1367, doi:10.1002/ 

ps.2225. 

17. Kamiyama, M.T.; Guedot, C. Varietal and Developmental 

Susceptibility of Tart Cherry (Rosales: 

Rosaceae) to Drosophila suzukii (Diptera: Drosophilidae). 

J. Econ. Entomol. 2019, 112, 1789–1797, 

doi:10.1093/jee/toz102. 

18. Pelton, E.; Gratton, C.; Guédot, C. Susceptibility 

of cold hardy grapes to Drosophila suzukii 

(Diptera: Drosophilidae). J. Appl. Entomol. 2017, 

141, 644–652, doi:10.1111/jen.12384. 

19. Stockton, D.G.; Brown, R.; Loeb, G.M. Not berry 

hungry? Discovering the hidden food sources 

of a small fruit specialist, Drosophila suzukii. Ecol. 

Entomol. 2019, een.12766, doi:10.1111/een.12766. 

20. Sial, A.A.; Roubos, C.R.; Gautam, B.K.; 

Fanning, P.D.; Van Timmeren, S.; Spies, J.; Petran, 

A.; Rogers, M.A.; Liburd, O.E.; Little, B.A.; et al. 

Evaluation of organic insecticides for management 

' 

of spotted-wing drosophila (Drosophila suzukii) in 

berry crops. J. Appl. Entomol. 2019, 143, 593–608, 

doi:10.1111/jen.12629. 

21. Gress, B.E.; Zalom, F.G. Identification and risk 

assessment of spinosad resistance in a California 

population of Drosophila suzukii. Pest Manag. Sci. 

2019, 75, 1270–1276, doi:10.1002/ps.5240. 

22. Van Timmeren, S.; Mota-Sanchez, D.; Wise, 

J.C.; Isaacs, R. Baseline susceptibility of spotted 

wing Drosophila (Drosophila suzukii) to four key 

insecticide classes. Pest Manag. Sci. 2018, 74, 78–87, 

doi:10.1002/ps.4702. 

23. Leach, H.; Van Timmeren, S.; Isaacs, R. Exclusion 

Netting Delays and Reduces Drosophila 

suzukii (Diptera: Drosophilidae) Infestation in 

Raspberries. J. Econ. Entomol. 2016, 109, 2151–2158, 

doi:10.1093/jee/tow157. 

24. Leach, H.; Moses, J.; Hanson, E.; Fanning, 

P.; Isaacs, R. Rapid harvest schedules and fruit 

removal as non-chemical approaches for managing 

spotted wing Drosophila. J. Pest Sci. (2004). 2018, 

91, 219–226, doi:10.1007/s10340-017-0873-9. 

25. Tarara, J. Microclimate modification with 

plastic mulch. HortScience 2000, 35. 

26. Kasirajan, S.; Ngouajio, M. Polyethylene and 

biodegradable mulches for agricultural applications: 

A review. Agron. Sustain. Dev. 2012, 32, 

501–529, doi:10.1007/s13593-011-0068-3. 

27. Greer, L.; Dole, J.M. Aluminum foil, aluminium-painted, 

plastic, and degradable mulches 

increase yields and decrease insect-vectored viral 

diseases of vegetables. Horttechnology 2003, 13, 

276–284. 

28. Croxton, S.D.; Stansly, P.A. Metalized polyethylene 

mulch to repel Asian citrus psyllid, slow 

spread of huanglongbing and improve growth of 

new citrus plantings. Pest Manag. Sci. 2014, 70, 

318–323, doi:10.1002/ps.3566. 

29. Nottingham, L.B.; Kuhar, T.P. Reflective Polyethylene 

Mulch Reduces Mexican Bean Beetle (Coleoptera: 

Coccinellidae) Densities and Damage in 

Snap Beans. J. Econ. Entomol. 2016, 109, 1785–1792, 

doi:10.1093/jee/tow144. 

30. Nottingham, L.B.; Beers, E.H. Management of 

Pear Psylla (Hemiptera: Psyllidae) Using Reflective 

Plastic Mulch. J. Econ. Entomol. 2020, doi:10.1093/ 

jee/toaa241. 

31. Dreves, A.; Cave, A.; Lee, J. A Detailed Guide 

for Testing Fruit for the Presence of Spotted Wing 

Drosophila (SWD) Larvae. Oregon State Univ. Ext. 

Serv. 2014, EM 9096, 1–9. 

32. Rendon, D.; Hamby, K.A.; Arsenault-Benoit, 

A.L.; Taylor, C.M.; Evans, R.K.; Roubos, C.R.; Sial, 

A.A.; Rogers, M.; Petran, A.; Van Timmeren, S.; 

et al. Mulching as a cultural control strategy for 

Drosophila suzukii in blueberry . Pest Manag. Sci. 

2019, doi:10.1002/ps.5512. 





New Findings on Limb 

Dieback of Figs in California 

Pruning Practices Can Help Protect 

from Disease Pathogen 

By THEMIS J. MICHAILIDES | Plant Pathologist, UC Davis/Kearney Agricultural Research and Extension Center 

DAVID MORGAN | Staff Research Associate, UC Kearney Agricultural Research and Extension Center 

and GIORGIO GUSELLA | Graduate Student in Plant Pathology, University of Catania, Italy 

Back in 2004, and again in recent 

years, there were concerns by fig 

growers mainly in Madera and 

Merced counties about an excessive 

killing of major branches of their fig 

trees (Figure 1). Visits to some orchards 

back then and recently indicated 

that indeed they had a major problem. 

Initial close examinations of the dead 

branches showed symptoms which 

were similar to another disease: branch 

wilt of walnut. 

The bark of dead fig branches had 

cracks and one could easily remove 

large pieces of the bark, exposing the 

woody tissues underneath which were 

covered by a black powder. Rubbing 

this black powder with your finger 

could easily remove masses of it (Figure 

2, see page 25). The inner surface 

of the broken and removed bark pieces 

were also black due to these powder 

masses. A lot of trees had many dead 

major branches while others had one 

or two dead along with other branches 

bearing chlorotic and thin canopy, distinct 

from the green and dense canopy 

of healthy branches. 

Figure 1. Left, Fig tree affected by severe limb dieback; top right, still active canker; bottom 

right, inactive canker (branch is dead) (all photos courtesy G. Gusella.) 

Pathogen Activity 

To collect samples, we cut some of the 

symptomatic branches close to the 

interface of dead and alive-looking 

(green) tissues. We noticed that in a 

cross section, the dead woody tissues 

were delineated from the healthy tissues 

by a dark brown line while the living 

woody tissues were white (Figure 1). 

Slices of these woody tissues from the 

branches were taken, isolations were 

made in the laboratory and a fungus 

known to be a pathogen of woody 

tissues was consistently recovered. 

The name of this pathogen is Neoscytalidium 

dimidiatum, which is a new 

taxonomic name of Hendersonula 

toruloidea fungus, which represents 

the pathogen first reported to cause the 


PLANT HEALTH & PEST MANAGEMENT 

FIGHT WITH 

BIOLOGICAL BITE 

Figure 2. Top, Neoscytalidium dimitiatum, the 

cause of limb dieback producing spores (arthrospores) 

as the mycelia dried up and separate to 

small segments under the bark; bottom, easily 

rubbing off the spores under the bark (photo 

courtesy Beth Teviotdale.) 

branch wilt disease of walnut. 

Checking the literature, the same 

fungus under a different name (i.e. 

Nattrassia mangifera) was reported in 

1945 on commercial figs in California 

as well as on Ficus religiosa and Ficus 

bengalensis, causing dieback and trunk 

cankers. In addition to walnut branch 

wilt, which is a common disease of walnuts 

grown in the San Joaquin Valley, 

the same fungus was reported in causing 

branch wilt and dieback of poplar, 

eucalyptus and mango. In other reports, 

we found out that this pathogen 

can cause killing of major branches of 

walnut, ash trees and grapefruit. More 

recently, it has been reported causing 

cankers and hull rot of almond. On fig 

shoots, the pathogen grows and infects 

injured bark (i.e. mechanical wounds, 

wounds by hail or sunburn), invades 

the woody tissues and kills the branch. 

When the branch is killed, it dries and 

usually the bark cracks, exposing large 


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Figure 3. Left, pycnidia protruding through bark cracks; right, arthrospores of Neoscytalidium dimidiatum causing limb dieback of fig. 


masses of black spores. These are not true spores but are 

small segments of mycelia that become black as the tissues 

dry up and break down into small pieces, producing a layer 

of black powder under the bark. The fungus also produces 

pycnidia that protrude through small cracks of the bark (See 

Figure 3). However, it is the spores produced in masses by 

the breaking mycelia called arthrospores. that can be spread 

readily by air and/or splashing rain and can cause infections 

of pruning wounds and other injuries of branches. 

Survey of Affected Areas 

Before doing pathogenicity studies with the Neoscytalidium 

fungus, we wanted to make sure that this fungus was found 

frequently throughout the area where fig trees showed similar 

symptoms to the ones we initially observed in Madera 

County. Therefore, a survey of 16 fig orchards with branch 

dieback symptoms, representing all the major fig varieties 

(Black Mission, Calimyrna, Conadria and the male trees 

(Roeding and Stanford caprifig varieties)) was done in Fresno, 

Madera and Kern counties. Neoscytalidium was isolated in 

all of these orchards. 



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Figure 4. Susceptibility of various fig cultivars to limb dieback 

pathogen Neoscytalidium dimidiatum. 

Dr. Themis Michailides sampling symptomatic fig trees. 


Figure 5. Effect of stress factors (mallet wounding and sunburn) 

and treatment with white wash affecting the severity of limb 

dieback of fig. 

Limb and branch samples from the majority of these orchards 

had 60% to 100% Neoscytalidium, while three had 7% to 11%, 

and two 26% to 32%. In 12 of these orchards, a second pathogen, 

Phomopsis spp., was isolated along with Neoscytalidium in the 

first year of the survey. Phomopsis sinarencis has been reported in 

California causing an epidemic on Kadota figs back in 1935 and in 

other countries as an important fig canker pathogen. By the third 

year of this survey, less Phomopsis was isolated, and, very recently, 

almost none was isolated, probably because the very susceptible 

Kadota variety is rarely now planted in California. Phomopsis is 

known as a pathogen fungus associated with canker diseases in 

many other crops around the world, but more investigations are 

needed to figure out its role in fig limb dieback. 

Differences in Susceptibility 

To determine if there were any differences in susceptibility to the 

limb dieback pathogen, we inoculated six cultivars directly in the 

field. We found that three months after inoculations, the cultivars 

Kadota, Black Mission and Sierra developed twice as long canker 

size than the cultivars Brown Turkey, Calimyrna and Conadria (Figure 

4). Growers also reported that they see the problem to be more 

severe in Black Mission than other cultivars. Inoculations of six cultivars 

showed that Neoscytalidium is a plant pathogen that likes high 

temperatures. For instance, it cannot grow below 50 degrees F; its optimum 

temperature for growth is 90 to 95 degrees F, and it can even 

grow at 104 degrees F to some extent. Therefore, this fungus likes hot 

summer temperatures and prefers to infect sunburned branches and 

pruning wounds. 

Figure 6. Effect of Surround® spray on the severity of limb 

dieback of fig. 

In experiments, we inoculated shoots of fig of different ages, including 

current growth (green) shoots, one-year, two-year and threeyear-old 

shoots, by wounding and inoculating with either a mycelial 

plug or a spore suspension. Interestingly, the three-year-old shoots 


developed almost three-fold larger cankers 

than the cankers on current and the 

one-year-old shoots. This suggests that 

larger cuts in the field during pruning 

seem to be more susceptible to infection 

than cuts made in current or one-yearold 

shoots. Also, inoculations done in 

May, June and July resulted in larger 

cankers than those done from August to 

November. ‘ 

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When we compared infection on pruning 

wounds done in winter vs. those done in 

summer, pruning wounds in the summer 

developed almost threefold larger 

cankers than those done during winter 

months. Therefore, it is recommended 

that pruning of figs should be done in 

winter when pruning wounds seem to be 

less susceptible. Figs can be protected 

from infections of the branch wilt pathogen 

if shoots are painted with whitewash 

to protect them from sunburn. Applying 

Surround® on shoots also protected the 

shoots from infection, and this is recommended 

to become a routine practice 

by fig growers. Figure 5 shows results of 

inoculation experiments done following 

various treatments in the field and artificial 

inoculation with the pathogen. 

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Although wounding by only mallet or 

only sunburn resulted in larger canker 

than the non-inoculated, un-wounded/ 

un-treated shoots, the shoots that were 

damaged by mallet wounding and sunburn 

at the same time resulted in the 

longest cankers. White wash or spraying 

with Surround protected the shoots 

even after wounding with mallets and 

inoculation (Figure 5 and 6, see page 

28). Therefore, pruning that exposes 

the shoots to sunburn and or any other 

type of wounding should be avoided, 

and spraying with Surround will help 

protect the fig shoots from the limb 

dieback pathogen. 

The authors thank the California Fig 

Institute for funding this research and 

a number of fig growers who allowed us 

to sample their orchards. 




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Field R&D Mgr, Trécé, Inc 

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Enhancing Diamondback 

Moth Management 

with Mating Disruption 

By SURENDRA K. DARA | UCCE Entomology and Biologicals Advisor 

Brussels sprouts field in Santa Maria (photo by S.K. Dara.) 

Brassica crops such as broccoli, 

brussels sprouts, cabbage, canola, 

cauliflower, collards, kale, kohlrabi, 

turnip and mustards are important 

vegetable or oilseed crops. The value 

of brassica vegetables, also known as 

cole crops, is more than $1.2 billion in 

California, which is the leading producer 

of these crops. Among various arthropod 

pests that attack brassica crops, the 

diamondback moth (DBM), Plutella 

xylostella (Lepidoptera: Plutellidae), is of 

significant importance. Thought to be of 

European origin, now with worldwide 

distribution, DBM exclusively feeds on 

cultivated and weedy crucifers. DBM 

can have up to 12 generations per year, 

especially under warmer climate. 

Female moths deposit 150 eggs on average. 

Four larval instars feed on foliage 

and growing parts of young plants or 

bore into heads or flower buds, resulting 

in skeletonization of leaves, stunting 

of the plants or failure of head formation 

in some hosts. Pupation occurs 

on the lower surface of leaves or in 

florets. Adult moths are grayish-brown, 

and when at rest, a light-colored diamond-shaped 

pattern can be seen on the 

upper side of the wings. 

Farmers typically rely on synthetic and 

biological insecticidal applications for 

controlling DBM. Multiple species of 

parasitoids and predatory arthropods 

also provide some control. Due to a 

heavy reliance on insecticidal control, 

DBM resistance to several insecticides 

is a common problem. Resistance of 

DBM to Bacillus thuringiensis (Ferré et 

al., 1991), abamectin (Pu et al., 2009), 

emamectin benzoate, indoxacarb and 

spinosad (Zhao et al., 2006), pyrethroids 

and other insecticides (Leibee and 

Savage, 1992; Endersby et al., 2011) have 

been reported from around the world. 

Excessive use of any kind of pesticide 

leads to resistance problems (Dara, 

2020) to an individual pesticide or multiple 

pesticides. 

Integrated pest management (IPM) 

strategy encourages the use of various 

control options for maintaining pest 

control efficacy and reducing the risk of 

resistance development (Dara, 2019). 

Regularly monitoring pest populations 

to make treatment decisions, rotating 

pesticides with different modes of 

action, exploring the potential of biocontrol 

agents, and other non-chemical 

control approaches such as mating 

disruption with pheromones are some 

of the IPM strategies for controlling 

the DBM. While sex pheromones are 

effectively used to manage several 

lepidopteran pests and are proven to be 

a critical IPM tool, mating disruption is 

not fully explored for controlling DBM. 

A study was conducted in Brussels 

sprouts to evaluate the efficacy of a 

sprayable pheromone against the DBM 

and to enhance current IPM strategies. 

Methodology 

The study was conducted on a 10-acre 

Brussels sprouts field in Santa Maria. 

Cultivar Marte was planted in early 

July for harvesting in December 2020. A 

typical diamondback control program 

includes monitoring DBM populations 

with the help of sticky traps and lures 

and applying various combinations of 

biological and synthetic pesticides at 

regular intervals. This study evaluated 

the efficacy of adding CheckMate 

DBM-F to the grower standard practice 

of monitoring the DBM populations 

with traps and lures and applying 

pesticides. Treatments included 1.) 

grower standard pesticide program 

(See Table 1) grower standard pesticide 

program with two applications of 3.1 fl 

oz of CheckMate DBM-F on August 9 

and September 11. Treatment materials 

were applied by a tractor-mounted 

sprayer using a 100 gpa spray volume 

and necessary buffering agents and 

surfactants. Each treatment was five 

acres and divided into four quadrants 

representing four replications. 

In the middle of each quadrant, one 

Suterra Wing Trap was set up with a 


Trécé Pherocon Diamondback Moth 

Lure. Lures were replaced once a month 

in early September and early October. 

Sticky liners of the traps were replaced 

every week to count the number of 

moths trapped. Traps were placed on 

Aug. 1, 12 and 24, Sept. 1, 11, 18 and 27, 

and Oct 6, and the moth counts were 

taken from respective traps on Aug. 

8 and 20, Sept. 1, 11, 18 and 27, and 

Oct. 6 and 15. CheckMate DBM-F was 

applied at 3.1 fl oz/ac on Aug. 9 and 

Sept. 11. The number of larvae and 

their feeding damage on a scale of 0 to 

4 (where 0=no damage, 1=light damage, 

2=moderate damage, 3=high damage, 

4=extensive/irrecoverable) were 

recorded from 25 random plants within 

each replication on Aug. 30 and Oct. 6 

and 18. Data were subjected to analysis 

of variance using Statistix software and 

significant means were separated using 

Tukey’s HSD test. The retail value of 

various pesticides was also obtained to 

compare the cost of treatments. 

When CheckMate DBM-F[(Z)-11-Hexadecenal 

(3) , (Z)-11-Hexadecen-1-yl 

Acetate (1)] was applied the first time 

on Aug. 9, Dibrom 8 Emulsive was 

replaced with Warrior II, the buffering 

agent Quest was not used, and the surfactant 

Dyne-Amic was replaced with 

Induce (dimethylpolysiloxane) to avoid 

potential compatibility issues. The 

impact of this substitution is expected 

to be negligible within the scope of this 

study. The retail cost of 3.1 fl oz Check- 

Mate DBM-F is $45.60. The cost of lures 

and traps would be about $4 to $8 per 

acre for a six-month crop like Brussels 

sprouts. 

Results and Discussion 

Traps in replication 4 in both treatments 

on August 8 and replication 1 in the 

grower standard were missing, probably 

knocked down by a tractor. The 

day before CheckMate DBM-F was first 

applied, the mean number of adult DMB 

caught was 227 in the grower standard 

and 271 in the plots that would receive 

the pheromone application (Figure 

1, see page 32). There was a gradual 

decline in moth counts during the 

rest of the observation period in both 

treatments. However, the decline was 

1 

2 

3 

4 

5 

6 

7 

8 

9 

Date 

Pesticides 

29 July Crymax (Bacillus thuringiensis subsp. 

kurstaki) 1 lb (IRAC 11) 

Proclaim (emamectin benzoate) 4.8 oz (6) 

Avaunt (indoxacarb) 3.5 oz (22A) 

Dibrom 8 Emulsive (naled) 1 pt (1B) 

9 August Crymax 1 lb (11) 

Radiant SC (spinetoram) 7 fl oz (5) 

Dibrom 8 Emulsive 1 pt (1B) 


Proclaim 4.8 oz (6) 

Avaunt 3.5 oz (22A) 



Radiant SC 7 fl oz (5) 

Warrior II (lambda-cyhalothrin) 1.8 fl oz (3A) 

1 September Crymax 2 lb (11) 




Lannate SP (methomyl) 1 lb (1A) 

Rimon 0.83EC (novaluron) 10 fl oz (15) 


*Exirel (cyantraniliprole) 20 fl oz (28) 

Lannate SP 1 lb (1A) 


Lannate SP 1 lb (1A) 

*Movento (spirotetramat) 5 fl oz (23) 


2 October Crymax 2 lb (11) 

Avaunt 3. 5 oz (22A)Lannate SP 1 lb (1A) 

*Movento 5 fl oz (23) 


higher in the plots that received Check- 

Mate DBM-F. The number of moths 

per trap were about 19% higher in the 

pheromone-treated plots compared to 

Buffering agents 

& Surfactants 

Quest (ammonium 

sulfate, phosphoric 

acid, and carbamide) 

buffering agent 1.4 pt 

Dyne-Amic (methyl 

esters of C16-C18 fatty 

acids, polyalkyleneoxide 

modified 

polydimethylsiloxane, 

alkylphenol ethoxylate) 

organosilicone-based 

nonionic surfactant 

Quest 1.2 pt 

Dyne-Amic 1 pt 

Quest 1.2 pt 

Dyne-Amic 1.2 pt 

Retail 

cost 

$129.04 

$108.51 

$145.63 

Dyne-Amic 12 fl oz $93.65 

Quest 1 pt 

Dyne-Amic 12 fl oz 

$72.64 





10 15 October Crymax 2 lb (11) 



Total cost $1,275.93 

Table 1. Pesticides, buffering agents and surfactants, their active ingredients, rates/ac (along 

with the IRAC mode of action groups) and retail pricing for those applied in the grower standard 

diamondback moth control program. 

*Applied diamondback moth and aphid control 

the grower standard before the study but 

were nearly 98% lower by the end of the 




study (Figure 2). The reduction in moth 

populations from mating disruption was 

significant on September 18 (P =0.039) and 

October 15 (P = 0.006). 

The mean number of larvae per 25 plants 

in a replication was zero on all observation 

dates except for 0.01 on Aug. 30 in the 

plots that received CheckMate. Four insecticide 

applications made by the time the 

study was initiated and the remaining six 

applications effectively suppressed larval 

populations. 

Larval feeding damage ratings were 

consistently low (P < 0.0001) in the plants 

that did not receive CheckMate DBM-F 

(Figure 3). The damage was limited to the 

older leaves at the bottom of the plants 

and must have been from early feeding 

before the initiation of the study. The lack 

of larvae and the evidence of new feeding 

damage also confirm that the crop remained 

healthy and pest-free. 

Yield and Cost Comparisons 

Since frequent pesticide applications 

effectively suppressed larval populations 

and prevented their feeding damage, the 

effectiveness of mating disruption on larval 

populations or their damage could not 

be determined in this study. Moths found 

in the traps probably developed from the 

larvae in the field or could have been those 

that flew in from other areas. 

However, lower moth populations in 

CheckMate DBM-F treatment demonstrated 

the overall influence of mating disruption 

and pest suppression. 

It is common to make about 10 to 12 pesticide 

sprays during the six-month crop 

cycle of Brussels sprouts. The cost of each 

application varied from about $73 to $192 

depending on the materials used with an 

average cost of about $128 per application 

in this study. The cost of two CheckMate 

DBM-F applications is $91. If diamondback 

moth populations could be reduced 

with mating disruption, it is estimated 

that two to three pesticide applications 

could be eliminated. That results in $164 

to $292 of saving for the pesticide costs 

and additional savings in the application 


Number of moths/traps 

Damage Rating 

300 

250 

200 

150 

100 

50 

0 

1.5 

1.0 

0.5 

0.0 

8/8/2020 

8/20/2020 

8/30/2020 

P < 0.0001 

Diamondback Moth Occurrence 

Grower Standard 

9/1/2020 

9/11/2020 

Larval Feeding Damage 


9/18/2020 

10/6/2020 

P < 0.0001 

Figure 3. Feeding damage by diamondback moth larvae. 

GS+CheckMate 

9/27/2020 

Figure 1. Mean number of diamondback moth adults found in the traps. 

20.00 

0.00 

-20.00 

-40.00 

-60.00 

-80.00 

-100.00 

8/8/2020 

GS+CheckMate 

10/6/2020 

% Control from CheckMate DBM-F 

8/20/2020 

9/1/2020 

9/11/2020 

9/18/2020 

9/27/2020 

10/6/2020 

10/18/2020 

P = 0.0074 

10/15/2020 

10/15/2020 

Figure 2. Reduction in moth populations by adding pheromone for mating disruption. 


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better hardware, and better quality. 

From nuts to citrus to vegetables, 

CheckMate ® and Puffer ® are trusted 

on more acres than any other mating 

disruption brand. 

Ready for 2021? 

Contact your local representative 

to schedule a virtual or outdoor 

consultation. 

www.suterra.com

Diamondback moth larva and adult (photos by Jack Kelly Clark, UC IPM.) 

Feeding damage in cauliflower (photo by S.K. Dara.) 

Adult diamondback moths on the last observation date in treatments 

with and without the pheromone (photos by Tamas Zold.) 


costs per acre by investing $91 in the 

mating disruption. Since DBM can 

develop resistance to several chemical 

and natural pesticides, eliminating 

some applications as a result of mating 

disruption also contributes to resistance 

management along with potential 

negative impact of pesticides on 

the environment. Compared to other 

mating disruption strategies, a sprayable 

formulation compatible with other 

agricultural inputs is easier and more 

cost-effective to use. 

The grower’s yield data showed 762 

cartons/acre from the grower standard 

block with pesticides alone and 814 cartons/acre 

from the block that received 

pesticide and pheromone applications. 

Although there seems to be a 7% yield 

difference, since data from individual 

plots could not be collected for statistical 

analysis, the impact of DBM mating 

disruption on yield improvement is 

inconclusive. 

This study demonstrated that mating 

disruption with CheckMate DBM-F will 

significantly enhance the current IPM 

practices by reducing pest populations, 

contributing to insecticide resistance 

management, and reducing pest management 

costs. Additional studies with 

fewer pesticide applications that allow 

larvae to survive and cause some damage 

might further help to understand 

the role of mating disruption where pest 

populations are not managed as effectively 

as in this field. 

Thanks to the PCA and grower for their 

research collaboration, Tamas Zold for 

his technical assistance in data collection, 

Ingrid Schumann for market research 

of pesticide pricing and Suterra for the 

financial support. 

References 

Dara, S. K. 2019. The new integrated pest management 

paradigm for the modern age. J. Int. Pest 

Manag. 10: 12. 

Dara, S. K. 2020. Arthropod resistance to biopesticides. 

Organic Farmer 3 (4): 16-19. 

Endersby, N. M., K. Viduka, S. W. Baxter, J. Saw, D. 

G. Heckel, and S. W. McKechnie. 2011. Widespread 

pyrethroid resistance in Australian diamondback 

moth, Plutella xylostella (L.), is related to multiple 

mutations in the para soidum channel gene. Bull. 

Entomol. Res. 101: 393. 

Ferré, J., M. D., Real, J. Van Rie, S. Jansens, and M. 

Peferoen. 1991. Resistance to the Bacillus thuringiensis 

bioinsecticide in a field population of Plutella 

xylostella is due to a change in a midgut membrane 

receptor. Proc. Nat. Acad. Sci. 88: 5119-5123. 

Leibee, G. L. and K. E. Savage. 1992. Evaluation 

of selected insecticides for control of diamondback 

moth and cabbage looper in cabbage in Central 

Florida with observations on insecticide resistance 

in the diamondback moth. Fla. Entomol. 75: 585- 

591. 

Pu, X., Y. Yang, S. Wu, and Y. Wu. 2009. Characterisation 

of abamectin resistance in a field-evolved 

multiresistant population of Plutella xylostella. Pest 

Manag. Sci. 66: 371-378. 

Zhao, J-Z., H. L. Collins, Y-X. Li, R.F.L. Mau, G. D. 

Thompson, M. Hertlein, J. T. Andaloro, R. Boykin, 

and A. M. Shelton. 2006. Monitoring of diamondback 

moth (Lepidoptera: Plutellidae) resistance to 

spinosad, indoxacarb, and emamectin benzoate. J. 

Econ. Entomol. 99: 176-181. 





Interesting! 


Vegetable Growers Express 

Impressions, Concerns and 

Hope for Crop Biostimulants 

New survey helps researchers understand the current use 

and attitudes of biostimulants in California vegetable crops. 

By ZHENG WANG | UCCE Vegetable Crops Farm Advisor, Stanislaus County 

Crop biostimulants are many things. First, they are 

claimed to be multi-functional, including enhancement 

of soil and crop health, acceleration of soil nutrient 

cycling and improvement of crop productivity and fruit 

quality, among other benefits. Second, they are categorized 

by the active ingredient, application method, cost and target 

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crops. Third, they are popular among ever-greater numbers 

of vegetable farmers regardless of production system, scale 

and commodity. Finally, some of their performance/efficacy 

is variable, while many others are unknown. 

According to Grand View Research Inc., the global revenue 

generated by biostimulants was $1.74 billion in 2016, 

dominated by European and North American companies. 

Projections indicate that the market value will reach $4.14 

billion by 2025. 

Though it is difficult to obtain an exact number of biostimulant 

products currently on the market, the estimate is 

over 600 with more becoming available each year. However, 

County of California 

Stanislaus 

Kern 

Santa Barbara 

San Luis Obispo 

San Joaquin 

Fresno 

Monterey 

Imperial 

Yolo 

Sutter 

Merced 

Sacramento 

Madera 

Yuba 

Riverside 

San Bernardino 

San Diego 

Santa Cruz 

Santa Clara 

Ventura 

Solano 

No. of grower responses 

34 

3 

1 

1 

14 

5 

3 

3 

7 

2 

10 

2 

1 

1 

2 

1 

1 

1 

2 

1 

1 

Table 1. List of counties for the respondents’ vegetable field locations. 


this grand prosperity of crop biostimulants is not shared 

equally among people who use them. Particularly to vegetable 

growers who operate farming at every scale that differs 

widely in climates, production timing, marketable portion, 

planting techniques, field preparation and maturity, it can 

be extremely complex to choose the right product from the 

long list and use it at the right time in the right way. The first 

and maybe the foremost step toward a more effective use of 

crop biostimulants among vegetable growers is to understand 

their current use, experience, concerns and hopes. To 

accomplish the task, a survey was sent 

out to collect the specific information 

from vegetable growers mainly in the 

San Joaquin Valley and other counties 

in California. 

The Survey and Respondent 

The survey was sent to approximately 

648 vegetable growers in late October 

2020 with the help of other UCCE 

advisors and commodity boards. The 

survey was then closed about two 

months thereafter before the responses 

were summarized. The original survey 

can be found at cestanislaus.ucanr.edu/ 

Agriculture/Vegetable_Crops/Biostimulant_Survey/. 

The survey contains 

eight questions with the first four 

asking growers how they farm and the 

last four related to their experience 

and opinions to crop biostimulants. By 

the end of December 2020, we received 

a total of 83 responses (12.8%), with 74 

of them being valid responses (11.4%). 

Nine responses were not included 

because there were two replies without 

an answer to any of the question, five 

responses from oversea, and two responses 

from counties outside California. 

Details about the composition and 

production of the 74 respondents are 

included below and in Table 1. 

By production, there were 10, 27 and 

37 growers claiming organic only, conventional 

only and mix of both. 

By scale, there were 31, 7 and 36 growers 

with vegetable production scale 

below 100 acres, 100 to 500 acres and 

over 500 acres. 

ORGANIC 

By commodity, crops with more than 10 responses included 

tomato (46), pepper (23), melon (21), summer/winter squash 

(21), leafy greens/herbs (21), cole crops (16), watermelon (16) 

and onion (13). 

By production location, the 74 growers claimed to have their 

vegetable fields in 21 counties across California. For details, 

see Table 1. 

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Responses Regarding 

Biostimulants 

The responses indicated that over half 

of respondents (40) know some knowledge 

about biostimulants, of which 37 

applied biostimulants to at least one or 

two of their vegetable crops. There were 

nine growers who claimed having the 

highest knowledge level (very well), but 

two of them did not use biostimulants 

to any of their vegetable crops. There is 

no surprise that the majority of growers 

who responded with just a little knowledge 

or not knowing anything about 

crop biostimulants did not apply any 

biostimulant to any of their vegetable 

crops. The respondents were almost 

equally distributed by the application 

level of biostimulants (Table 2). The 

survey also asked the previous experience 

or future impression regarding the 

efficacy of biostimulants on improving 

vegetable growth. From the results, 

50 growers, representing 68% of total 

respondents, shared the experience or 

impression that biostimulants could 

conditionally confer their efficacy. Less 

than 20% of the respondents indicated 

a consistent, positive performance on 

improving their vegetable crops, while 

only 13% gave the negative impression 

on biostimulant efficacy (Figure 1). 

Concerns and Hopes 

I have received numerous questions in 

the past years from vegetable growers, 

their advisors and colleagues regarding 

the biostimulant selection, effect evaluation, 

quality control and incompatibility 

with other field activities. “Going 

in blind”, “Unable to identify the 

benefits”, and “Snake oil” are common 

complaints. One of the main objectives 

for the survey is to identify the biggest 

concerns of using biostimulants on 

vegetable crops among growers. The 

survey results showed that about half of 

the respondents identified the difficulty 

of choosing a proper product as one of 

the main concerns followed by the risk 

of low or no return on investment. In 

addition, concerns of incomplete label 


Application level 

of biostimulants 

Apply to most 

vegetables. 

Apply to certain 

vegetables. 

Apply to one or 

two vegetables. 

I don’t use to 

any vegetables. 

Sub-total 

Figure 2. 

38 Progressive Crop Consultant March / April 2021 

Stanislaus 

Kern 

Santa Barbara 


San Joaquin 

Fresno 

Monterey 

Imperial 

Yolo 

Sutter 

Merced 

Sacramento 

Madera 

Yuba 

Riverside 


San Diego 

Santa Cruz 

Santa Clara 

Ventura 

Solano 

Understanding level of biostimulants 

Very well Some A little Nothing 

3 

3 

1 

2 

9 

Table 2. Number of grower responses to the understanding/knowledge level of 

biostimulants and how much of vegetable crops growers apply biostimulants to. 

10 

14 

13 

3 

40 

34 

3 

1 

1 

14 

5 

3 

3 

7 

2 

10 

2 

1 

1 

2 

1 

1 

1 

2 

1 

1 

Figure 1. Responses to previous experience or future impression regarding 

biostimulant efficacy. 

5 

6 

9 

20 

5 

5 

Sub-totoal 

18 

17 

20 

19 

Total: 74 

Figure 2. Growers’ concerns regarding the use of crop biostimulants on vegetable crops.


and interference with fertilization and 

pesticide plans received 20 responses 

(Figure 2, see page 38). Lastly, the 

survey asked growers their agreement 

level to future actions of improving 

the use of crop biostimulants. For all 

future measures, an average of 89% of 

the respondents agreed/strongly agreed 

that they will be helpful and important 

to improve future use of crop biostimulants 

(Table 3). These responses reflect 

the hopes from growers, and their 

voices should be heard by academia, 

industry, extension and other sectors to 

outline future efforts aiding a practical 

and profitable use of these biologics. 

Future Measures 

Implement more unbiased 

field trials to validate the 

efficacy of different 

biostimulants. 

Provide more instructions/ 

education on selecting, using, 

and evaluating biostimulants. 

Offer more user-friendly 

resources aiding practical 

use of biostimulants. 

Standardize/improve 

product labels and 

manufacturer-claimed 

functions. 

Number of responses to each agreement level 

Strongly Agree Agree Neutral Disagree Strongly Disagree 

35 

35 

31 

34 

31 

32 

35 

30 

Table 3. Number of responses to the agreement on the importance of future measures in 

improving the use of biostimulants. 

2 

3 

5 

6 

3 

1 

1 

2 

3 

3 

2 

2 

UCCE Biostimulant Testing Trials 

The UCCE farm advisors from Stanislaus 

County are actively working with 

vegetable growers and biostimulant 

companies to conduct various testing 

trials each year. The main goal is to 

fill the data gap with more unbiased, 

statistically-viable product efficacy data 

on various vegetable commodities in 

the Central Valley. Since 2019, we have 

evaluated numerous biostimulants on 

processing tomato and watermelon 

productivity, fruit quality and plant 

health. Stay tuned to our newsletter 

and check for previous results 

(Veg Views: cestanislaus.ucanr.edu/ 

news_102/Veg_Views/). 

Helping Farmers Grow NATURALLY Since 1974 

FEATURING: 

Stanislaus 

Kern 

Santa Barbara 


San Joaquin 

Fresno 

Monterey 

Imperial 

Yolo 

Sutter 

Merced 

Sacramento 

Madera 

Yuba 

Riverside 


San Diego 

Santa Cruz 

Santa Clara 

Ventura 

Solano 

34 

3 

1 

1 

14 

5 

3 

3 

7 

2 

10 

2 

1 

1 

2 

1 

1 

1 

2 

1 

Office: 1559-686-3833 Fax: 559-686-1453 

2904 E. Oakdale Ave. | Tulare, CA 93274 

newerafarmservice.com 


References 

Biofertilizers Market Size, Share & Trends Analysis 

Report By Product, By Application, And Segment 

Forecasts, 2012 – 2022. grandviewresearch.com/ 

industry-analysis/biofertilizers-industry. 

NAVEL ORANGEWORM MANAGEMENT 




CIDETRAK ® 

NOW MESO 

— Allan Crum, 

Farmers International 

Allan’s IPM Program 

LEARN MORE 

® 

Tomato (46) and watermelon (16) each represented 

crops with more than 10 submitted 

responses (photos by Z. Wang.) 

INCORPORAT ED 



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Life After Methyl Bromide in 

California Berries 

Growers lean on newer fumigant alternatives to control 

key weed and disease pests. 

BY WARREN E. CLARK, Contributing Writer 

When methyl bromide was 

banned in 2005, California 

strawberry growers lost an 

effective tool in their crop care toolbox 

to control weeds, soilborne diseases, 

nematodes and symphylans. Special-use 

permits allowed them to continue using 

the fumigant through 2016, but growers 

feared final loss of the powerful soil 

fumigant might be the end of profitable 

production. 

The California Strawberry Commission 

agreed, noting that elimination of 

methyl bromide fumigation brought 

forth several soilborne diseases for 

which there is no post-plant control. Of 

particular concern were Fusarium wilt 

(Fusarium oxysporum f.sp. fragariae), 

Verticillium wilt (Verticillium dahlia) 

and charcoal rot (Macrophomina 

phaseolina), according to the California 

Strawberry Commission. 

But once again, necessity proved to 

be the “mother of invention,” said 

independent agronomist and PCA Lee 

Stoeckle, owner of Stoeckle Agricultural 

Consulting in Ventura, Calif. 

Stoeckle has advised strawberry and 

caneberry growers for more than 

30 years, and he noted that effective 

alternative fumigants have taken up 

the methyl bromide void and are now 

widely and successfully used. While 

California strawberry acreage has 

fallen, total production has actually 

increased thanks to innovation and 

application of new technology. 

Stoeckle’s family-owned business 

provides recommendations on 3,000 

acres of strawberries and 100 acres of 

blackberries in Santa Barbara County 

and San Luis Obispo County and 

2,000 acres of strawberries in Ventura 

County. In addition, he consults on 

production of 800 acres of strawberry 

and 250 acres of raspberries in Baja 

Mexico. While he is primarily responsible 

for above-ground insect and disease 

control, he doesn’t write fumigation 

recommendations but instead advises 

based on what he learns about weeds 

and soil pathogens. 

A One-Two Punch 

Top problem soilborne diseases, 

according to Stoeckle, are Fusarium, 

Macrophomina, Phytophthora, Anthracnose 

and Verticillium wilt. Top 



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problem above-ground pests include 

two-spotted spider mites, Lygus bug, 

Botrytis fruit rot/gray mold and powdery 

mildew, depending on varietal 

susceptibility. Other pests necessary to 

watch include worms and aphids. 

“The optimum disease and weed control 

program is a one-two punch,” Stoeckle 

says. “Hit it at the end of the season as a 

burndown and at the beginning before 

next planting via drip irrigation. The 

backbone of our control program is 

Pic-Chlor 60 EC (1,3-dichloropropene 

plus chloropicrin) at the max recommended 

rate (350 lbs/ac), going after 

the heavy hitting ‘big boys’ (soilborne 

diseases) when applied in August 

or September before planting.” He 

recommends Vapam or K-Pam to get 

the additional benefits to control these 

diseases (Fusarium, Verticillium, Macrophomina 

phacelia) and eliminate the 

inoculum reservoir in the crown. 

Stoeckle says emulsified formulations 

of Telone ® C-35 and chloropicrin 

can be applied with irrigation water 

through drip irrigation systems. 

Metam sodium is the active ingredient 

in Vapam ® HL and metam potassium 

in the active ingredient in K-Pam ® 

HL . Both are AMVAC ® soil fumigants, 

which give off methyl isothiocyanate 

(MITC) when combined with water via 

drip or otherwise. If drip fumigation 

is planned, good results have been 

obtained with a sequential application 

of chloropicrin or 1,3-dichloropropene 

plus chloropicrin, followed 7 days later 

with metam sodium or 

metam potassium. 

Stoeckle considers fumigants essential 

and offers the math: “If we equate the 

value of every plant to be $2 each and 

you lose 10% of your plants, that’s 2,500 

plants on a population of 25,000 per 

acre. Your choice is to fumigate or take 

a $5,000 loss. That’s an easy decision. 

The return on investment on fumigation 

is huge. We expect to see a 20% to 

30% return on fumigant investment.” 

He is quick to add there are other management 

decisions that help maximize 

production, noting, “I could go on and 

on about using the best plastic mulch or 

optimum fertilization practices.” 

Best Practice Weed Control 

Reduces Production Costs 

Fifth-generation Santa Barbara County 

grower Brett Ferini, owner of Rancho 

Laguna Farms, grows 400 acres of 

strawberries (300 fall plant, 100 summer 

plant) and 20 acres (adding another 

20 for 40 total) of blackberries. Plus, he 

grows 35 acres of organic blackberries. 

He used Vapam on blackberries in 

February 2020. 

“Vapam worked out really well in 

controlling nutgrass/nutsedge,” he said. 

“Pic-Clor 60 has no effect.” 

For weed and disease control, “we hit 

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everything at fall pre-plant with Pic- 

Clor 60 through drip tape and seven 

days after that we follow with Vapam,” 

he said. “It does a terrific job on nutsedge 

and other weeds, as well as the 

soilborne diseases including Verticillium, 

Phytophthora and, anecdotally, 

Macrophomina.” 

Ferini says the operation plans to add 

a Vapam burndown at the end of the 

2020 growing season 

“We definitely [have] cut weeding by 

60% on summer plant,” he says. “Labor 

is our highest cost. We saw $1,050 

savings per acre vs. our normal costs of 

$1,800/acre. The big test will be on the 

fall plant when we get more rain. Our 

fall weeding cost normally runs $2,800 

to $3,000 per acre. Using Pic-Clor 60 

followed by Vapam treatment, I expect 

weeding cost savings of $1,000 to 

$1,500 per acre.” 

Also seeing results with soil fumigants 

is Santa Barbara grower Josh Ford. He 

is COO of Ocean Breeze Ag Management 

LLC in Ventura, which grows 

450 acres of strawberries, 50 acres of 

blackberries, and 25 acres of raspberries. 

Ford’s biggest soilborne pests 

are Macrophomina, Fusarium, and 

Phytophthora cactorum. Nutgrass is 

his most difficult weed to control. 

“We’ve been using soil fumigants for 

many years,” he says. “We were using 

methyl bromide, but now we apply 

chloropicrin once a year and K-Pam 

once to twice a season. If nut grass is 

a bad problem, we will knock it down 

at the end of the season with K-Pam 

and also pre-plant K-Pam. Our ROI is 

good when you consider the increased 

cost of labor to manually remove nut 

grass.” 

Comments about this article? We 

want to hear from you. Feel free to 

email us at article@jcsmarketinginc. 

com 

Finding the right fumigation and herbicide 

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Understanding CCA Certification Exams 

By JEROME PIER, Ph.D. | CCA, PCA, Board Chairman, Western Region Certified Crop Advisors 

I 

never really understood what 

certification means until I heard it 

described by a psychometrician. I have 

been a Certified Crop Advisor (CCA) for 

nearly two decades and felt I knew what 

it means to be a certified professional. I 

recently attended the North American 

Certified Crop Advisors On-line Board 

Meeting. I listened to a presentation by 

Scott Thayn, Ph.D., CMS, a psychometrician, 

or a statistician specializing in 

distinguishing the differences between 

individuals. Thayn is the president of 

Certification Management Services, the 

third-party agency hired by the Agronomy 

Society to help develop and manage 

the testing required for certification. The 

presentation addressed a proposal to 

give rankings on how well a test taker 

did on the CCA exam. Board members 

were hearing from potential members 

who were unable to pass the exams 

and wanted more feedback to help 

them study for their next attempt. The 

proposal, and the way the statistician 

took it apart, were a revelation, and it got 

me thinking that the mechanics behind 

certification are not well understood. 

Certification Exam Intricacies 

The Home page for Certifications under 

the website Agronomy.org states, “Certification 

is the standard by which professionals 

are judged. The purpose of a certification 

program is to protect the public and 

the profession. It is a voluntary enhancement 

to a person’s career credentials. Being 

certified adds credibility and shows that 

you are serious about what you do.” 

A prospective candidate digging deeper 

would find they need to meet certain 

criteria to be considered a CCA: academic, 

experience and examination. Simply 

speaking, certification indicates one has 

demonstrated the knowledge and experience 

to perform at a higher level than their 

peers. 

Hearing the proposal to give test takers 

feedback on their performance was 

familiar to me as a board member who 

participates on the Exam Committee for 

the Western Region. I have heard from 

many colleagues who did not pass 

one or both certification exams and 

are frustrated by the lack of a score 

or indication where they underperformed. 

I struggled to explain to my 

friends why the exams were pass/fail 

and why they just had to keep trying. 

I believe the frustration lies in the 

expectations of an academic testing 

experience clashing with the reality 

of certification exams. 

Data indicates most people who take 

the certification exams are recent 

college graduates. Having a college 

degree in agriculture is a requirement for 

becoming a certified crop advisor. College 

graduates have spent most of their lives 

with graded exams. Academic testing presents 

a broad range of questions to both examine 

a student’s proficiency and encourage 

them to improve. A student who gets 

a low grade on a test will hopefully review 

the questions marked incorrect and study 

the subject to raise their grade on the final 

exam. This familiar approach to testing is 

contrary to certification exams. 

The distribution of difficulty of certification 

exam questions is quite narrow compared 

to an academic exam (See Figure 1). 

The certification exam begins by defining 

competency areas, the major subjects 

that define the everyday work of the crop 

advisor. Performance objectives rest under 

the competency areas. Each performance 

objective spawns several possible exam 

questions. Each exam question must be 

tied to a performance objective to accurately 

test one’s comprehensive knowledge 

of agronomy. 

Where an academic exam contains a large 

variation in question difficulty, certification 

exam questions ask, “What is the 

minimum knowledge a professional must 

have to be proficient in this area.” This is 

determined by groups of volunteer CCAs, 

with guidance by the Agronomy Society’s 

excellent statistician Dawn Gibas, Ph.D., 

who reviews the performance of each exam 

question. Questions that nearly everyone 

gets right are eliminated as well as those 

that almost no one answers correctly. A 

Figure 1. Distribution of ease of questions in an 

academic exam compared to certification testing. 

complete exam review process takes place 

every four to five years. 

An illustration of the difference between 

academic and certification exams can be 

given with a sports analogy. An academic 

exam is comparable to a high school 

physical education track and field program, 

where everyone is expected and encouraged 

to participate. A certification exam, 

on the other hand, is like the selection 

process for the Olympic high jumping 

team. The high school physical education 

program sets the bar low and gradually 

raises it to help students practice their 

technique and jump higher. But when the 

world competition is jumping over seven 

feet, the US team would set the bar at a level 

near that to select the most competitive 

team. During the selection process, if the 

bar is set too high, then they don’t have a 

team, but set the bar too low and the team 

has a poor chance of winning. When the 

psychometrician used this example, the 

proposal to classify the specific abilities of 

test takers was withdrawn. 

The complexity of 21 st -century agriculture 

practiced in the Western Region of the US 

supports the need for the most qualified 

field people providing the best recommendations 

for our growers so we can continue 

to deliver the highest-quality, safest agricultural 

products in the world. 





Apply less, expect more? 

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a nutrition plan that meets the unique goals, climate and challenges we face. 

Get precisely the advanced products and agronomic knowledge you need to 

support your crops, your soil and a sustainable future. 

Find an AgroLiquid dealer near you. 

AgroLiquid.com 

 

Sure-K® and Kalibrate® are registered 

trademarks and PrG is a trademark of AgroLiquid. 

© 2020 AgroLiquid. All Rights Reserved.

Potassium 

A Vital Nutrient for tree Nuts 

Top growers depend on the convenience and effectiveness of 

KTS® (0-0-25-17S) for consistent, quality crops. Maximize your 

potassium applications this year with immediately available 

potassium and Sulfur from Crop Vitality. 

Learn more about KTS® here: 

or visit www.cropvitality.com. 

©2021 Tessenderlo Kerley, Inc. All rights reserved. KTS ® is a registered trademark of Tessenderlo Kerley, Inc.

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