PCC Sep Oct 2019


September/October 2019

Non-Botrytis Fruit Rots of Strawberry:

Under-Estimated and Under-Researched?

Assessing the Impact of Irrigation Water Quality on

Strawberry Cultivars

California's Prune Orchard of the Future

Colletotrichum Dieback in California Citrus

Evaluating Biostimulant and Nutrient Inputs to Improve

Tomato Yields and Crop Health


Volume 4 : Issue 5

Photo courtesy of Luke Milliron.


September 26th | 1:00PM - 9:00PM

September 27th |

7:00AM - 1:15PM

September /October 2019

For more information

and the full agenda

see pages 50-55

www.progressivecrop.com 1


for our 2019-2020 Trade Shows

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In 2018-2019 we had:

January 21, 2020 (Orland, CA)

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Total Attendees

Come experience our

shows for YOURSELF!

Alm nd Day

June 24, 2020 (Fresno, CA)

September 26-27, 2019 (Visalia, CA)

November 20, 2019 (Tulare, CA)

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October 24, 2019 (Bakersfield, CA)



JCS Marketing Inc.


2 Progressive Crop Consultant September /October 2019



Non-Botrytis Fruit Rots

of Strawberry:

Under-Estimated and


Grape Trunk Diseases

10 and Management

Assessing the Impact of

Irrigation Water Quality

18 on Strawberry Cultivars

California’s Prune Orchard

26 of the Future

Colletotrichum Dieback in

32 California Citrus


Evaluating Biostimulant

and Nutrient Inputs to

Improve Tomato Yields

and Crop Health

Mechanistic Insight

into the Salt Tolerance

44 of Almonds

The Crop Consultant

Conference Full Menu of

50 Workshops and Seminars




PUBLISHER: Jason Scott

Email: jason@jcsmarketinginc.com

EDITOR: Kathy Coatney


Email: article@jcsmarketinginc.com

PRODUCTION: design@jcsmarketinginc.com

Phone: 559.352.4456

Fax: 559.472.3113

Web: www.progressivecrop.com


Andre Biscaro

Irrigation and Water Resources

Advisor, UCCE, Ventura


Mark Bolda

Farm Advisor and County

Director, UCCE

Michael Cahn

Irrigation and Water Resources

Advisor, UCCE, Monterey


Surendra K. Dara

Entomology and Biologicals

Advisor, UCCE

Greg W. Douhan

UCCE Area Citrus Advisor for

Tulare, Fresno and Madera


Akif Eskalen

Department of Plant Pathology,

UC Davis

Katherine Jarvis-Shean

UCCE Orchards Systems

Advisor for Sacramento,

Solano and Yolo Counties

Steven Koike

Director, TriCal Diagnostics

Kevin Day

County Director and

UCCE Pomology Farm

Advisor, Tulare/Kings County

Steven T. Koike,

Director, TriCal Diagnostics

Ed Lewis

Former Associate Dean,

College of Agricultural and

Environmental Sciences,

University of California, Davis

Dani Lightle

UCCE Orchards Systems

Advisor for Glenn, Butte and

Tehama Counties

Joey S. Mayorquin

Department of Microbiology

and Plant Pathology, UC


Themis Michailides

Professor and Plant

Pathologist, UC Davis

Luke Milliron

UCCE Farm Advisor for Butte,

Glenn and Tehama Counties

Franz Niederholzer

UCCE Farm Advisor for

Colusa, Sutter and Yuba


Gabriel Torres

UCCE Farm Advisor, Tulare




Emily J. Symmes

UCCE IPM Advisor,

Sacramento Valley

Kris Tollerup

UCCE Integrated Pest

Management Advisor,

Parlier, CA

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


September /October 2019



Non-Botrytis Fruit

Rots of Strawberry:

Under-estimated and Under-Researched?

BY MARK BOLDA | Farm Advisor and County Director, UCCE

AND STEVEN KOIKE | Director, TriCal Diagnostics

Growers face a multitude of

obstacles when trying to

produce large volumes of

high-quality strawberry fruit for a

market that runs for many months.

Up-front, pre-plant ground preparation

and transplant costs are significant

financial commitments that are expensed

before even a single strawberry

plant is put in the ground. Untimely

rains and insect infestations can result

in loss of fruit quality and numbers.

A series of soilborne pathogens can

later cause plant collapse and loss of

profit. Of course, the intractable labor

shortage dilemma may even result in

perfectly marketable fruit not reaching

the consumer.

When it comes to diseases of the strawberry

fruit, the number one concern

is gray mold (also called Botrytis fruit

rot), which justifiably attracts the rapt

attention of field professionals and

captures the interest of researchers.

However, in coastal California another

fungal issue can also take its toll on

strawberry yields and quality and in

many ways is overlooked and underestimated

by the industry. Rhizopus fruit

rot and Mucor fruit rot are collectively

known as “leak” disease; this disease

concern also deserves to be recognized

and studied.

Symptoms, Signs, Diagnosis

In the field, leak symptoms and signs

only develop on mature or near-mature

4 Progressive Crop Consultant September /October 2019



All photos courtesy of Steve Koike.

Photo 1. Two pathogens, Rhizopus and Mucor, can turn strawberry fruit into black lumps.

fruit and are very distinctive. Infected

red fruit first take on a darkened,

water-soaked appearance; in short

order the fruit will begin to wrinkle and

collapse. Almost overnight the rapidly

growing Rhizopus or Mucor pathogen

will be visible as white fungal growth

peppered and interspersed with tiny

black spheres. Fungal growth will be

extensive and can entirely envelop the

fruit, turning it into a white and black

lump (Photo 1). Rhizopus and Mucor

produce pectolytic (endopolygalacturonase)

and cellulase enzymes as they

colonize the strawberry, disintegrating

the fruit tissues and causing red juices

(Photo 2, see page 6) to ooze and flow

onto the plastic that covers the bed. It is

because of these messy red juice flows

that the designation “leak” is used for

this disease.

This ugly scene in the field, however,

is only part of the problem that these

fungi cause. During harvest infected

but symptomless fruit, as well as healthy

fruit exposed to spores of the two

pathogens, will be packed into containers.

The pathogens can continue to grow

during postharvest handling, storage,

and market display of fruit, causing

postharvest fruit losses, shortening of

shelf life of the product, and creating a

mess in crates and clamshells (Photo

3, see page 6). In fact, if fruit are not

properly refrigerated, the fungus on a

single infected fruit can rapidly spread

throughout an entire container, resulting

in what is known as “nesting” or

Continued on Page 6


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Mycelial Growth Spore Producing Bodies Overall Colony Color Fungus ID

Table. Description of various fungi found on post-harvest strawberry.

Continued from Page 5

clumping of oozing, rotted fruit. Harvested

strawberry fruit are subject to a

number of rotting molds; the leak fungi

are generally identifiable due to the

color and nature of the fungal growth

(see Table).

The Pathogens

Much is already

known about the

two fungi causing

strawberry leak

disease. Rhizopus

and Mucor are both

in the group of fungi

called Zygomycetes. Both fungi are

commonly found in agricultural environments

and cause similar ripe fruit

rots on crops such as apricot, cherry,

peach, pear, and tomato. While closely

related to each other and difficult to differentiate

in the field, the two pathogens

differ slightly. On California strawberry,

Rhizopus tends to be the more commonly

encountered pathogen. Rhizopus

grows very rapidly and haphazardly in

orientation, creating a web-like mess of

mycelium (Photo 4, see page 7). Rhizopus

forms a brown orange, root-like

structure (called rhizoids) that allows it

to quickly spread between adjacent fruit

(Photo 5, see page 7). The black, spherical

spore bearing structures produce

huge numbers of dry spores that are

readily spread by winds (Photo 6, see

page 8). Mucor grows more slowly with

an upright, erect mycelial habit (Photo

7, see page 8) and also produces spores

on a black spherical structure (Photo

8, see page 8). However, Mucor spores

collect in a wet droplet surrounding

the head; such spores are therefore less

prone to dispersal by winds.

Both fungi survive and increase in the

field by colonizing dead organic matter

and debris; Rhizopus and Mucor also

readily colonize discarded and overripe

strawberry fruit left on the plant

or thrown into the furrow. These fungi

produce a resilient structure (zygospore)

that resists drying and weathering

Photo 2. The leak pathogens produce enzymes that cause

strawberry fruit to ooze juice.

Photo 3. Enzymes released by Rhizopus and Mucor can

cause significant fruit breakdown during storage and


6 Progressive Crop Consultant September /October 2019

Photo 4. Rhizopus growth is rapid and results in a messy, weblike

mycelial growth.

Photo 5. Brown-orange root-like structures allow

Rhizopus to rapidly spread between adjacent fruit.

and provides another means of survival.

Both Rhizopus and Mucor can be readily

isolated from soil, thereby demonstrating

that these fungi can persist in

fields even if strawberry is not present.

Once strawberry fruit begin to develop

and ripen, spores come in contact

with the fruit and usually gain entry

via wounds and injuries. Strawberry

leak pathogens tend to be more active

if temperatures are relatively warmer,

generally 65° F or higher. This temperature

factor may be one reason that leak

disease is more damaging in coastal

California in late summer through early

fall. The pectolytic enzyme that causes

fresh market fruit to melt into juices can

also be a concern in some processed

fruit products. The enzyme is heat-stable

and withstands canning temperatures;

for example, apricot halves and

brined cherries that are contaminated

with Rhizopus and then canned may

end up being apricot or cherry mush

because of the continued activity of the

stable enzyme even though the original

fungus is cooked and dead.

Management Options and Research



effective solutions

for Agriculture

Fungicide – Bactericide

Miticide – Insecticide – Fungicide

Broad Spectrum Insecticide

Growers already know to refrigerate

strawberries as soon as possible after

field packing the fruit. Refrigeration is

a primary management tool for reducing

losses due to leak disease. While

refrigeration generally limits the development

of Rhizopus, it is notable that

some species of Mucor can grow quite

well at storage temperatures of 32° F (0°

Continued on Page 8


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September /October 2019

Insecticide – Miticide - Repellent


Disease Control



Continued from Page 7

C). Therefore, one research need is the precise

identification of

Rhizopus and Mucor

species present in

strawberry fields.

Different species

will have different

temperature optima

regarding growth

and ability to infect

fruit in the field, and

the different species may respond differently to

postharvest conditions.

Photo 6. The black, spherical spore-producing head of Rhizopus

releases thousands of wind-borne spores.

Photo 7. On strawberry fruit, the Mucor pathogen grows with an

upright, erect mycelial habit.

Sanitation, both in field and during harvest, is

another means of limiting leak development.

Reducing the amount of over-ripe and rotted

fruit in the field may help limit the Rhizopus and

Mucor inoculum present in the planting; the influence

of field sanitation on inoculum is another

area of needed research. Field sanitation may

be an increasingly difficult goal to attain given

labor shortages and costs. Sanitation during the

harvest process mainly involves the training and

education of harvesters. Harvesters who touch

and handle leak fruit will easily transmit the fungus

to healthy fruit that are packed. Therefore,

pickers should be reminded not to touch leak

fruit and to be sure not to pack fruit showing any

hint of leak infection.

Fungicides can effectively limit Rhizopus development

for some crops. However, such information

is lacking for strawberry. Research is needed

to determine the efficacy and feasibility of using

fungicides for leak management in strawberry.

Other interactions involving fungicides should

also be investigated. There are indications that

fungicides used to manage Botrytis could exacerbate

growth by Rhizopus and Mucor.

Among the many challenging factors facing

strawberry growers, leak disease is not the number

one concern. However, during certain times

of the year in coastal California, leak disease

can affect a significant amount of the harvest. A

better understanding of strawberry leak disease,

achieved through collaborative research, may

help this industry manage this problem and improve

on an already excellent commodity.

Photo 8. Mucor also produces a black, spherical head, though the

spores are captured in a droplet and are not readily spread by wind.

Comments about this article? We want to hear

from you. Feel free to email us at


8 Progressive Crop Consultant September /October 2019

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September /October 2019






All photos courtesy of Gabriel Torres.

Grape Trunk

Diseases and


BY GABRIEL TORRES | UCCE Farm Advisor, Tulare County


Trunk disease” is a catch-all term

that includes several different

fungal diseases of grapevines

trunks worldwide. The term was

coined in the late 1990s by Dr Luigi

Chiarappa¹, and can include foliar and

vascular symptoms caused by Petri

disease, Black foot, Eutypa, Botryosphaeria

dieback, Phomopsis dieback

and Esca. Most of the fungi (more than

50 species) causing trunk disease are

related, belonging to the order Botryosphareales,

but fungi that belongs to the

families that forms mushrooms can

be also recovered from the cankers. In

most of the cases, the cankers interfere

with the movement of water from the

roots to the leaves, shots and clusters.

Photo 1. Esca tiger strip symptom on Autumn King.

Petri disease and Esca are caused by the

closely related species of fungi in the genus

Phaeomoniella and Paheoacremonium.

In both diseases, longitudinal black

stripes are visible under the bark. Different

from Petri disease which occurs

in vines younger than three years, Esca

is observed in more mature plants. The

foliar symptom can include the wellknown

“Tiger Stripe” pattern (Photo

1). This symptom is visible normally by

the end of June, when high temperatures

stress the vines. Reddish-brown

patches on the leaves are observed in

Continued on Page 12

Disease Appearance Leaf Symptoms Shoot Symptom Trunk Symptom

Petri disease

Black foot






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Photo 2. Measles s.

Continued from Page 10

red cultivars, while yellow patches are

more common on white grapes. Esca is

also known as “black measles” because

the dark spots that develop on berries

(Photo 2). Measles is particularly

damaging to table grapes because berry

appearance is paramount.

Black foot is caused by two species of

the fungal genus Cylindrocarpon, and

it most commonly observed on young

vines (three-year-old vines or younger).

Stunted vines and scorched leaves (Photo

3, see page 13) are a typical sign of

black foot. Affected roots present black

lesions and look like they are dead.

The disease was reported by late 1990’s

in California and has been frequently

found in fields with poor planting practices,

especially those that were J-rooted

at planting. The disease if not prevented,

can require costly replanting.

Botryosphaeria is caused by more than

20 species of fungi. However, fungi in

the species Lasiodiplodia and Neofusicocum

are the most damaging. Spurs from

infected vines won’t develop new shoots

(Photo 4, see page 14) . In cross-section,

a pie shape necrotic lesion can be

observed in infected trunks (Photo 5,

see page 14), however this symptom

can be also observed in vines infected

with Eutypa.

Eutypa is a common disease in California,

and it is caused by the fungus Eutypa

lata. In addition to the pie shaped

internal lesion, proliferation of stunted

shoots is common (Photo 6, see page

14). This symptom is absent in Botryosphaeria

disease, where no growth or no

leaf symptoms are observed.

Phomopsis is normally associated with

damage on green tissue, especially canes

and leaves. However, when conditions

favor the pathogen, damage caused by

Phomopsis can result in death of spurs,

canes and buds. Severely affected canes

develop cracks and have a bleached ap-

12 Progressive Crop Consultant September /October 2019

Photo 3. Vines affected by black foot disease. Left: scorch symptoms.

pearance during winter. In early spring

reproductive structures of the pathogen

are visible as black speckles.


All the described trunk diseases can

be seen at any time of the vineyard

life, but normally they start to appear

between the third and the fifth year after

planting. They can appear alone, or in

combination, which can exacerbate the

plant stress. In general, by year 10 to 12,

20 percent of the plants show symptoms

when no preventive actions have

been implemented. At this point, trunk

diseases enter in an exponential phase,

reaching 75 percent of infection by year

15, and 100 percent by year 20.

Significant losses are associated with

Trunk Diseases Development



trunk disease development. Reduction

in number of clusters, decrease

in quality and cosmetic damages are

the most visible impacts in the field.

However, cost of replanting, and/or

retraining if grower elects to use vine

surgery, especially in young vineyards,

it also a major cost

associated with trunk

diseases. Siebert² in

2000, estimated the

annual loss caused

by Botryosphaeria

and Eutypa in the

California wine

grape industry was

$260 million. Similar

negative effects have

been reported in

other grape growing

areas and trunk



Trunk diseases are considered chronic

diseases, and unfortunately there is

no fungicide that can provide curative

action. Preventive management or the

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Continued on Page 14

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% Infection






5 10 15 20


Figure 1. Trunk disease infection development in unattended


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Photo 4. Lack of new shoots growth.

Photo 5. Typical symptom of botryosphaeria.

Continued from Page 13

removal of infected tissue from the vine

(surgery) and destruction by mulching

or soil incorporation of infected shoots

and canes are the only viable alternatives.

More than 95 percent of trunk disease

infections are associated with pruning,

or other cultural practices that leave

Photo 6. Stunted shoots proliferation on vine infected

with Eutypa.

pruning wounds exposed at a time

when the wounds may be infected.

Dispersal of the pathogens responsible

for causing trunk disease occurs during

rain events. Under California conditions

pruning and rain overlap during

the winter months (November-January).

Dr. Gubler and his team found that

delaying pruning closer to bud break

significantly reduces disease³. The logic

behind this is that in a typical California

year, rain is gone by the

end of February and the

days are warmer, letting

the plants recover

sooner than during the

colder days of December

and January.

In addition, some sap

movement (bleeding)

starts to be present in

February, helping the

plant to remove the

infective spores from

susceptible tissue.

However, and knowing

that the labor and

logistics doesn’t permit

all growers to postpone

pruning until the last part of the winter,

the use of fungicides to protect the exposed

tissues is important to reduce the

rate of the infection. The best practice

is to protect the plant any time there

are pruning wounds. This is especially

important if rain is expected following

pruning. If pruning is done in November

or December, it is advised at least

two sprays with protectant fungicides

be applied. If the pruning is postponed

until January and warmer days are

forecasted, one protectant spray after

pruning is ideal.

Another strategy for pruning is to do a

double pruning (pre-pruning + pruning).

It consists of pre-pruning the vines

between November and January. Then,

by the end of February or March, the

pruning process is completed. The objective

of this method is to remove any

potential infection occurred during the

winter months. A complementary fungicide

spray after the last pruning can

increase the control of trunk diseases.

In order to improve the efficacy of

Continued on Page 16

14 Progressive Crop Consultant September /October 2019


for our 2019-2020 Trade Shows

New Names, Same Great Experiences!

In 2018-2019 we had:

January 21, 2020 (Orland, CA)

January 10, 2020 (Yuba City, CA)

June 5, 2019 (Turlock, CA)

June 19-21, 2019 (Monterey, CA)


PCA/CCA Attendance


Total Attendees

Come experience our

shows for YOURSELF!

Alm nd Day

June 12, 2019 (Fresno, CA)

September 26-27, 2019 (Visalia, CA)

November 20, 2019 (Tulare, CA)

For more info visit: www.wcngg.com/events

October 24, 2019 (Bakersfield, CA)



JCS Marketing Inc.


September /October 2019



Last Profitable Year








25% 25% 25% 50% 50% 50% 75% 75% 75% No

3 5 10 3 5 10 3 5 10 Pract.

Percentage of control/year practice established

Figure 2. Calculated lifespan of profitable vineyard based on the efficacy of the

implemented practice and the year when they are implemented.

Continued from Page 14

protective fungicide, a closer identification

of the disease is recommended as

any particular fungicide cannot control

all possible pathogens. A recent report

done by Baumgartner and Brown⁴ on

their research in 2017, demonstrates

that Pristine, Topsin + Rally (in mixture),

and Luna had better preventive

control of Botryosphaeria and Phomopsis

dieback. Eutypa was controlled more

effectively with Pristine. The highest

control of Esca was obtained with

Serifel, but it only reached 64 percent.

Results in 2018 in the same study presented

different results and were mainly

associated with a different weather


Different studies, including the one

recently done by Dr. Baumgartner and

collaborators⁵, demonstrates that preventive

practices works better if they are

established during the first years of the

crop (Figure 2). Dr. Baumgartner estimated

that when more effective practices

are adopted early in the crop life,

it is expected to prolong the vineyard

rentability by at least 25 years.

Further information on trunk diseases

can be found at:

1) http://ipm.ucanr.edu/PMG/selectnewpest.grapes.html

2) Bettiga LJ, ed. Grape Pest Management,

Third Edition. University of

California, Agriculture and Natural

Resources; 2013. https://books.google.


3) Wilcox WF, Gubler WD, Uyemoto

JK, eds. Compendium of Grape Diseases,

Disorders, and Pests. Second. St

Paul, Minnesota, USA.: The American

Phytopathological Society; 2017.

4) Disease P, Gramaje D. Grapevine

Trunk Diseases: Symptoms and Fungi

Involved. 2018;102(1):12-39. https://



Cited literature:

1. Gramaje D, Úrbez-Torres JR, Sosnowski

MR. Managing Grapevine

Trunk Diseases With Respect to Etiology

and Epidemiology: Current Strategies

and Future Prospects. Plant Dis.

2018;102(1):12-39. doi:10.1094/PDIS-


2. Siebert JB. Economic Impact of

Eutypa on the California Wine Grape

Industry. Davis; 2000.

3. Gubler WD, Rolshausen P e., Trouillase

FP, et al. Grapevine trunk Diseases

in Califronia. Pract Winer Vineyard.

January 2005:1-9.

4. Baumgartner K, Brown AA. Protectants

for Trunk-disease management

in California table grapes. In: California

Table Grape Seminar. Visalia: California

Table Grape Commission; 2019:19-21.

5. Baumgartner K, Hillis V, Lubell

M, Norton M, Kaplan J. Managing

Grapevine Trunk Diseases in California

’ s Southern San Joaquin

Valley. 2019;3:267-276. doi:10.5344/


Comments about this article? We want

to hear from you. Feel free to email us at


16 Progressive Crop Consultant September /October 2019

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September /October 2019

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Assessing the Impact of Irrigation Water Quality on

Strawberry Cultivars

BY ANDRE BISCARO | Irrigation and Water Resources Advisor, UCCE Ventura County

AND MICHAEL CAHN | Irrigation and Water Resources Advisor, UCCE Monterey County


Strawberries are the third most

valued crop in California ($2.3

billion) and one of the most

sensitive to salinity. Limited information

on the tolerance of new varieties

to salt and chloride toxicity has led to

significant yield losses in recent years.

Even a modest yield loss of 5 percent

due to soil and water salinity may cost

the strawberry industry and California

$260 million per year. Despite the

importance, commonly used salinity

tolerance thresholds for strawberry

(Ayers and Westcot, 1985) are based on

studies almost a half-century old and

may not be applicable to the soils, water

quality, climate, and modern cultivars

grown in California. California production,

which accounts for approximately

85 percent of the strawberries produced

in the US, are mostly grown on coastal

soils with electrical conductivity (ECe,

saturated paste extract method) ranging

from 2 to 4 dS/m. Some of these soils

have moderate to high concentrations

of calcium, bicarbonate and sulfate.

Although most of these salts may be

precipitated in the form of calcium

sulfate (gypsum) and calcium carbonate

(lime) and have limited impact on plant

growth, the ECe can be considerably

increased when a soil sample is saturated

with distilled water (used in the

saturated paste extract method) due to

the dissolution of these salts. That is a

common scenario found in arid regions

such as in the Southwestern US (e.g.

Ventura County), where limited rainfall

contributes to the accumulation of certain

salts in the topsoil. In the Watsonville

area, however, there is much less

carbonate and sulfate in the groundwater

and therefore in agricultural

fields, where sodium and chloride are of

major concern. Excessive sodium most

often leads to high sodium adsorption

ration (SAR), which causes infiltration

problems on some soil types. In irrigated

agriculture, the irrigation water

quality and leaching fraction are usually

the main factors driving soil salinity.

When appropriate leaching amounts

are applied, the salinity of the soil and

of the irrigation water reach a steadystate

(equilibrium). However, when

irrigation amounts do not exceed crop

evapotranspiration (ETc), soil salinity

can increase considerably due to the

accumulation of salts in the rootzone.

Infiltration rate and rainfall also affect

soil salinity. In an attempt to account for

the precipitation effect of certain salts,

Rhoades et al. (1992) suggest that plants

can tolerate ECe about 2 dS/m higher

than published thresholds when grown

on gypsiferous soils (soils that contain

significant quantities of gypsum, or calcium

sulfate). Although this publication

provides basic management guidance,

strawberry growers and farm managers

need more detailed information to determine

leaching fractions and to select

irrigation water sources and cultivars.

Identifying the specific types of anions

and cations that make up the salts in

soil and irrigation water is important

for predicting how different strawberry

cultivars will tolerate salinity. For

example, a field with soil ECe of 2.5

dS/m, where chloride is approximately

10 meq/L can have significantly greater

impacts on strawberry yields than a soil

with the same soil ECe where chloride

is 2 meq/L and calcium and sulfates are

the predominate salts.

Material and Methods

In order to assess how susceptible

strawberry cultivars are to irrigation

water of different quality, a two-year

study was conducted in California

between 2016 and 2018. The first year of

the study consisted of a survey conducted

in 40 strawberry fields located

in the Oxnard and Watsonville districts,

Continued on Page 20

18 Progressive Crop Consultant September /October 2019

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Average 1.4

Standard Deviation 0.3

Average 1.1

Standard Deviation 0.5
































Table 1. Irrigation water chemical analysis average and standard deviation of 40 fields in the Oxnard and in

the Watsonville production districts, year 1 (2016/2017 season).

Continued from Page 18

where irrigation water and soil samples

were analyzed for salinity composition.

Overall, the irrigation water of the

fields located in the Oxnard district

had greater electrical conductivity and

significantly greater sulfate levels, while

chloride levels in the Watsonville fields

were twice as great as the Oxnard fields

(Table 1). These results were used as the

benchmark for determining the treatments

of the salinity tolerance experiment

conducted the following year.

The second year of the study consisted

of an experiment conducted in a commercial

field located in Oxnard, California

during the 2017/2018 production

season. Strawberry yield, soil salinity

and salts content in leaf blades of the

two most popular public cultivars in

Oxnard (cv. Fronteras) and in Watsonville

(cv. Monterey) were assessed under

eight salinity treatments following a

randomized complete block design.

Each plot was 30 feet long and 1 bed

wide (64 inches), with four plant rows,

approximately 90 plants/plot, and two

high flow drip tapes (0.67 gpm/100ft)

placed about 1.5 inch deep between

the 1st and 2nd, and between 3rd and

4th plant rows. The experiment was

planted on October 2017, and the treatments

started approximately a month

post-planting in

order to promote a

good establishment

Bring the

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weeds and

insects with

of the crop; during

that period, overhead


was the predominant irrigation

method. Drip irrigation amounts and

timing were decided based on ETc

estimations from the California Irrigation

Management Information System

(CIMIS station # 152) weather station,

and matric potential readings from tensiometers,

respectively. Water-powered

injection pumps (Figure 1) blended the

well water with concentrated salt solutions

formulated for each treatment at a

1:100 ratio during every drip irrigation

event from November 2017 to June

Continued on Page 22



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Continued from Page 20

2018 (total of 60 drip irrigations). The

treatments consisted of irrigation water

with two levels of elevated sodium adsorption

ratio (SAR, 4.6 and 6.6), three

levels of elevated chloride (4.2, 7.7 and

11.7 meq/L), and two levels of elevated

sulfate (18.3 and 26 meq/L of SO4). Table

2 displays a complete description of

the salts’ composition of each treatment.

Composite soil and leaf blade samples

were collected from each plot at early,

mid and late production stages and analyzed

for pH, ECe, Ca, Mg, Na, Cl, B,

HCO3, CO3 and SO4 (soil samples), and

N, P, K, S, B, Ca, Mg, Zn, Mn, Fe, Cu,

Na and Cl (leaf blade samples). Marketable

and unmarketable yield, and berry

weight were measured in average twice

a week from December 2017 through

June 2018, totaling 54 harvesting events.

There was a total of 5.8 inches of rainfall

throughout the entire growing season,

of which 4.8 inches happened in March,

between the first and second sampling


Results and Discussion

Total marketable yield of Fronteras

was significantly (P0.05). The high sulfate

treatment reduced Fronteras cv. marketable

yield by 10 percent, although

the differences were not statistically

significant (P=0.094). Yield losses due

to the elevated salts started before plant

symptoms were noticeable in Fronteras.

Total marketable yield of the Monterey

cultivar was not significantly affected

by any salinity treatment (Figure 3 and

Table 4, see page 24). Cull rates of both

cultivars were not affected by the salinity

treatments. Fronteras berry weight

was significantly reduced by 6.3 percent

with the highest chloride treatment

(11.7 meq/L). Salt concentrations in

soil and leaf blade samples consistent-

Continued on Page 24

22 Progressive Crop Consultant September /October 2019







Elevated SAR, I 1.7

Elevated SAR, II 2.1

Table 2. Chemical analysis of irrigation water treatments of year 2 (2017/2018

season). Values represent average of three samples collected from the drip tape

throughout the season.

Table 3. Total yield response to treatments, Fronteras cultivar.




Elevated CI, I

Elevated CI, II















5 Elevated CI, III 2.3 2.4 10.3 6.2 6.9 11.7 11.8



Figure 2. Total marketable yield of Fronteras cultivar displayed in boxplot graph;

in this graph, the box represents the limits between the 25th and the 75th

percentiles, and the whiskers represent the upper and lower endpoints. The

horizontal line inside the box represents the median.


Elevated SO4, I 1.8

Elevated SO4, II 2.3































8 Control 1.3 2.5 5.5 2.8 5.1 1.2 11.9

*Control water was provided by local water agency (United Water Conservation District).







Elevated SAR, I 70,626

Elevated SAR, II 68,795

Yield loss*






3 Elevated CI, I 68,850 6% 0.632

4 Elevated CI, II 64,075 13% 0.022

5 Elevated CI, III 61,160 17% 0.001



Elevated SO4, I 69,689

Elevated SO4, II 65,756

8 Control 73,393

*Compared to Control





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Elevated SAR, I 51,040

Elevated SAR, II 50,763

3 Elevated CI, I 51,725 3% 0.995

4 Elevated CI, II 53,296 0% 1.000

5 Elevated CI, III 50,812 5% 0.934



Elevated SO4, I 52,797

Elevated SO4, II 51,700

8 Control 53,243

*Compared to Control

Table 4. Total yield response to treatments, Monterey cultivar.

Yield loss*










Continued from Page 22

ly increased with the higher salinity

treatments for both cultivars (data not


The rainfall events that occurred between

the first and second samplings

contributed to significant leaching of

salts from the root zone (0-12 inch

depth), which made overall ECe values

from the second sampling date very

similar to the values measured during

the first date. Hence, yield losses

observed in this experiment may have

been greater, and occurred sooner if

the rainfall during that period had

been less. Additionally, plant symptoms

of the salinity treatments, which

were not observed until mid-May, may

have been observable sooner with less

intense precipitation. Overall, the most

surprising finding of this study is the

marked differences in yield response to

the salinity treatments between the two

cultivars. While Fronteras proved to be

highly susceptible to increased irrigation

water salinity, especially in regards

with chloride, Monterey cv. presented

limited and statistically not significant

yield declines. Accordingly, other major

public and proprietary strawberry

cultivars may also exhibit a range of susceptibility

to salinity. It is also reasonable

to expect greater yield losses of the

cultivar Fronteras grown on fields that

have been farmed with irrigation water

quality equivalent to the treatments of

this study for years. In that case, plant

establishment can be compromised by

the increased water and soil salinity, especially

if the irrigation wasn’t managed

with the appropriate leaching requirement

to the water quality. The fact that

the Monterey cultivar did not respond

to the salinity treatments included in

this study may be related to significantly

greater chloride levels found in the

irrigation water of the Watsonville area,

where the cultivar was selected and tested

before being released to commercial


In summary, the findings of this study

conclude that the strawberry cultivar

Fronteras is highly susceptible to elevated

chloride levels, and that salinity

effects on strawberry yield is cultivar

dependent. Although this study provides

conclusive information of salinity

effects on Fronteras and some information

about Monterey cultivar, the quest

to understanding the impact of salts on

the main strawberry cultivars is very

challenging and most likely far from

being achieved.


Ayers, R.S. and D.W. Westcot, 1985.

FAO Irrigation and Drainage Paper 29:

Water quality for agriculture. In Crop

tolerance to salinity. http://www.fao.


Rhoades, J.D., A. Kandiah and A.M.

Mashali. 1992. FAO Irrigation and

Drainage Paper 48: The use of saline waters

for crop production: http://www.


Comments about this article? We want

to hear from you. Feel free to email us at


Figure 3. Total marketable yield of Monterey cultivar displayed in boxplot graph.

24 Progressive Crop Consultant September /October 2019



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September /October 2019



California’s Prune Orchard

OF THE Future

BY LUKE MILLIRON | UCCE Farm Advisor for Butte, Glenn and Tehama Counties

AND FRANZ NIEDERHOLZER | UCCE Farm Advisor for Colusa, Sutter and Yuba Counties

AND DANI LIGHTLE | UCCE Orchards Systems Advisor for Glenn, Butte and Tehama Counties

AND KATHERINE JARVIS-SHEAN | UCCE Orchards Systems Advisor for Sacramento, Solano and Yolo Counties

Figure 1. An unheaded 2nd leaf prune tree in March 2017 in Glenn County with traditionally headed trees in the

background. This Glenn County grower is experimenting on their own with various tree training regimes.

California will likely have a large

prune crop in 2019 following

favorable bloom conditions and

lower yields in 2018. Unfortunately,

in prune production with larger crops

typically comes smaller fruit, of which

there is currently an over-supply in

the world market. High production of

small fruit world-wide has come at a

time when demand for small fruit from

consuming nations like China, Brazil,

and Russia has been in decline. California

handlers have been strongly urging

their growers to use shaker thinning to

reduce the fruit number during spring

and help deliver large, high-quality fruit

at harvest.

To be successful, the prune orchard of

the future is going to have to thread the

needle of achieving earlier production

in its life cycle and maintaining high

and consistent yields in maturity, all

while attaining large average fruit size

each year. Prunes come into production

later than many other orchard crops.

One way to increase early production

is to reduce or eliminate severe heading

26 Progressive Crop Consultant September /October 2019

cuts during tree training. Subsequently,

yield potential at orchard maturity may

be increased over historical production

levels in some situations by striking a

new balance between spacing and rootstock

vigor for increased canopy volume

and higher light interception. Finally,

the key mechanism for achieving more

consistent yields and larger fruit size in

prune production has been to thin the

crop with mechanical shaking following

good bloom conditions like we had this

year. Shaker thinning will likely continue

to be the foundation of consistent

yields for future orchards.

Pruning Prunes: Greater Early

Production by Avoiding Heading

Cuts During Establishment

University of California (UC) research

has shown that earlier and greater

production can be achieved in both

almonds and walnuts by reducing

the severity of pruning during tree

establishment. This has been done by

reducing or eliminating the use of severe

heading cuts (Figure 1) during tree

establishment. In pruning, “heading

cuts” reduce the length of a limb, while

“thinning cuts” completely remove the

limb. Although historical orchard tree

training often calls for severe heading

cuts (e.g. cutting back ½ or more of the

1st year growth during the first dormant

period), leaving limbs unheaded can

lead to earlier fruit production.

Bill Krueger, now a UC Cooperative

farm advisor emeritus, tested several

pruning regimes for newly planted

prune trees from 1996 through 2000.

The most successful of these pruning

regimes all minimized the severity of

pruning. Yield and profitability were

greatest in the treatment that selected

three to five scaffolds at the first dormant

and bent back competing limbs

(nearly to, or to the point of breaking

to reduce competitiveness). Competing

limbs were again bent at second and

third dormant, and finally limbs were

left unheaded at fourth dormant. In all

four years of this treatment, pruning

cuts were made for selective thinning

(complete limb removal) to help shape

the tree into a vase-shape and elimi-


Figure 2. Measuring both almond yield (kernel lbs/ac) and midday

photosynthetically active radiation (PAR) percentage have shown a direct

relationship of 40 kernel lb/ac per 1 percent PAR. Photo courtesy of

Lampinen Lab, UC Davis.

nate competing or crossing branches.

Other treatments that both yielded

well and had the highest total income

selected either 3 or 3-5 scaffolds and

either left those scaffolds unheaded or

lightly tipped in the first dormant. In

the 2nd, 3rd and 4th dormant these

other successful treatments had various

sequences of either being unheaded

(but still making thinning cuts) or leaving

the trees completely unpruned. By

contrast, the severe pruning treatment

that had the lowest cumulative dry yield

and income selected three scaffolds at

the first dormant and then headed new

limb growth back to 30 inches in the 1st

through 4th dormant.

You can read the full report from 2000,

which is the second listed report at:


Joe Turkovich, Winters area grower

and Chairman of the California Prune

Board developed his own minimal

pruning training method, which he

describes as a modified version of the

"long pruning" method described by

Krueger and others in the UC Prune

Production Manual. First used in the

early 1990’s, the goal of his approach

is to create an upright canopy framework

with a strong interior architecture

capable of bearing large crops without

the need for wiring, rope, or propping.

It allows for early bearing and isolates

breakage to flatter, bearing side limbs.

Continued on Page 28

September /October 2019



Continued from Page 27

It involves the almost exclusive use of

thinning cuts as opposed to heading

cuts. Turkovich heads the dormant

bareroot trees at 40 inches at planting

to allow space for vertical separation

between the future primary scaffolds.

Scaffolds are selected during October

of the first year of growth and left

unheaded. In May of the 2nd year, the

three scaffolds are lightly tipped back

(approximate height nine feet) to keep

them from bending out of position, and

approximately a third of new growth

is thinned out (in particular, removing

crossing-limbs, while allowing flat fruiting

wood to develop). In the dormant

period between year two and three (or

during the summer of year three) the

only pruning that occurs is to select

or promote the growth of secondary

leaders (two per scaffold). Again, no

heading cuts are done, and no attempt

is made to "open up the tree". Between

year three and four, again, no heading

cuts. Excessive side limbs are removed

or tipped to prevent over-bearing and

breakage and tertiary leaders are selected

or promoted, two per secondary

leader. In subsequent years he continues

to avoid heading cuts, never topping the

trees. If tree height needs to be reduced,

leaders are thinned back to strong side

upright limbs three to five feet below the

top of the tree. On 18' by 16' spacing,

Turkovich reports this orchard training

approach has yielded approximately 0.6

tons in the 3rd leaf, 1.2 in the 4th, 3.0 in

the 5th and an average of 4.5-5.5 tons/ac

of high-quality fruit in the 6th year and


Whether utilizing one of the minimal

pruning regimes tested by Bill Krueger

or the approach utilized by Joe Turkovich,

minimizing severe heading cuts

during tree establishment can lead to

improved early yields.

Tighter Spacing and Greater Light

Interception in the Prune Orchard of

the Future:

Increased Canopy Volume →

Increased Light Interception →

Increased Yield Potential

At maturity, higher yields could be

Figure 3. Two clusters of prune yield (dry tons/acre) versus midday light

interception (%), grouped by row spacing. Photo courtesy of E. Fichtner

and F. Niederholzer.

achieved in many California prune

orchards by capturing more light with

the choice of a more vigorous rootstock,

and/or planting at a closer spacing. We

all know that fruit and leaves grow on

branches, and that fruit need the sugar

production from neighboring leaves

to grow and sweeten. Thus, one way to

think about the yield potential of an orchard

is how many fruit-leaf groupings

(also called bearing units) are spread

out over the orchard. In other words,

increasing the amount of space in the

orchard taken up by the orchard canopy

(instead of open, unused space) will

increase your yield potential per acre.

One measure of canopy size is how

much light that canopy intercepts. Light

that is intercepted by the leafy canopy

and doesn’t reach the orchard floor is

measured as midday photosynthetically

active radiation (percent PAR). Work

by the laboratory of Bruce Lampinen,

University of California Cooperative

Extension (UCCE) orchard specialist

at UC Davis, has found that for every 1

percent of light that an almond orchard

captures there is an average of 40 lbs/ac

increased yield in all measured orchards

(Figure 2, see page 27). Lampinen has

found this relationship between greater

light capture and greater yield potential

in both almond and walnut production.

Light interception isn’t the only determinant

of yield of course, therefore

these are “potential” yields and depend

on proper irrigation, fertilization, pest

and disease management.

Light Interception and Yield

Potential in Prune Production

Although the relationship between

canopy light interception and yield

has not been as well studied in prune

production, there does appear to be a

clear relationship from the limited data

available (see Figure 3). Although there

is substantial variation, the denser 14

feet x 17 feet planting in this example is

achieving between 60-80 percent light

interception and is clearly out yielding

the wider spaced plantings that are only

capturing 30-45 percent of midday light,

common in many California prune

orchards. The 16 foot in-row spacings

of the wider plantings appear as discrete

trees (they do not touch), while the

spacing 14 feet by 17 feet have created

continuous hedgerows (Figure 4, see

page 30). This tighter (183 trees/acre)

spacing illustrates the 14 feet by 17 feet

6-8 dry tons/ac yield potential of prune

orchards in excellent cropping years.

Prune orchard spacing has historically

been determined by the constraints

of harvest equipment. However, some

growers are instead shifting this paradigm

and beginning to modify their

equipment to get through tighter

spacings. Many questions and potential

challenges arise due to this shift in paradigm

and will be addressed through

experimentation by innovative growers

and UC researchers.

For more considerations impacting

Continued on Page 30

28 Progressive Crop Consultant September /October 2019

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September /October 2019



Figure 4. Two orchards with contrasting spacing, light interception and yield potential. Left photo courtesy

of E. Fichtner. Right photo courtesy of F. Niederholzer.

Continued from Page 28

spacing and light interception, including

rootstock vigor and soil type, per

tree costs and mechanical hedging, see:



Consistent Large Fruit Size

The final component to remaining

competitive with the increased production

levels in Chile and Argentina, is

achieving large, high-quality fruit each

and every-year. The key approach to

achieving consistent large fruit size is

shaker thinning in years like 2019 when

a high percentage of flowers set fruit

(far too many for the tree to achieve a

large average fruit size). Fruit thinning

occurs roughly at “reference date” or

when 80-90 percent of fruit have a visible


Endosperm is a clear gel-like glob that

can be excised with a knife point from

the blossom end of the seed (Figure 5).

Reference date is roughly one week after

the pit tip begins to harden and timing

is typically late April or early May. Although

the earlier thinning is done, the

greater the effect will be on final fruit

size at harvest, if you thin too early you

can damage the tree without effectively

removing fruit.

UC Cooperative Extension orchard

farm advisor Dani Lightle developed a

great guide to shaker thinning that computes

the required calculations for you:

30 Progressive Crop Consultant September /October 2019


Thinning is a critical practice for several

reasons. When production of small

fruit is up worldwide at the same time

demand for small fruit is in decline,

achieving large average fruit size is an

absolute imperative. Not only do small

fruit have substantially less value (or

even no value in some cases), they are

costlier to harvest and dry. Setting a

large crop of small fruit can also be a

great stressor on an orchard creating a

large sink for potassium demand and

causing limb breakage. Finally, since

not every year’s bloom creates favorable

conditions for fruit set, over-cropping

can set up a vicious cycle of having fewer

flowers that will be blooming during

an uncertain bloom period in the subsequent

year. In other words, thinning

enables a high flower density each year.

Even if bloom conditions are poor and

set is low, a low percentage of fruit set

from a high number of flowers is much

better than low set from only a few

flowers. Mechanical thinning enables

the production of higher-value fruit,

avoids the drain of costly small fruit and

sets up the orchard for more sustainable

year-to-year production.

Three key practices for maximizing orchard

productivity are utilizing reduced

severity of pruning during canopy training,

achieving higher yield potential by

maximizing canopy light interception

and consistently attaining large average

fruit size through thinning. These

practices may be part of what gives the

California prune orchard of the future a

competitive edge in the global market.

This work is made possible by the

funding support of the California Prune

Board. Special thanks to Mark Gilles

(Sunsweet) for his input on prune

orchard spacing both historically and

currently. Special thanks also to Joe

Turkovich who kindly provided the details

of his modified version of the "long

pruning" method.

Comments about this article? We want

to hear from you. Feel free to email us at


Figure 5. Extraction of the

endosperm on a developing prune.

Photo courtesy of M.L. Poe.


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Dieback in



BY GREG W. DOUHAN | UCCE Area Citrus Advisor for Tulare,

Fresno, and Madera Counties

AND AKIF ESKALEN | Department of Plant Pathology, UC Davis

AND JOEY S. MAYORQUIN| Department of Microbiology and

Plant Pathology, UC Riverside

November 20th, 2019

7:00 AM - 1:00 PM

Tulare Fairgrounds

215 Martin Luther King Jr Ave, Tulare, CA 93274

For More Information, See Page 37

32 Progressive Crop Consultant September /October 2019

The 2017-2018 United States

(U.S.) citrus crop was valued at

3.28 billion dollars with California’s

citrus production accounting for

59 percent of the overall U.S. production.

Much of California’s bearing

acreage is devoted to orange production,

however other citrus varieties

of tangerine, mandarin, lemon and

grapefruit are grown throughout the

state. As the California citrus industry

contributes to over half of the total U.S.

citrus production, the identification

and management of new disease threats

is crucial.

Colletotrichum, a Globally

Distributed Fungus

Colletotrichum constitutes a large

genus of fungi which are known for

having diverse ecological roles ranging

from endophytes, fungi living within

plant tissues and causing no known

problems, to plant pathogens that can

kill entire plants or portions of the

plant. Colletotrichum includes some

important fungal pathogens of numerous

plant hosts including native and

agricultural plant species occurring in

tropical and subtropical regions in the

world. Colletotrichum is well-known for

causing various anthracnose diseases on

many plants, with general anthracnose

symptoms including necrotic lesions

on various plant parts including stems,

leaves, flowers and fruits. Although

Colletotrichum is primarily described

as causing anthracnose diseases, other

diseases such as rots caused by Colletotrichum

spp. have been documented.

Currently, over 100 species of Colletotrichum

have been described and

recent phylogenetic studies (which

show the relationship among organisms)

based on the analysis of DNA has

found that at least 71 unique phylogenetic

species exist within three well

known ‘species’ of Colletotrichum based

on traditional morphology; C. gloeosporioides,

C. acutatum, and C. boninense.

The large species diversity within the

Colletotrichum genus highlights the

importance of DNA phylogenies to

accurately identify species. With respect

to citrus, two species of Colletotrichum,

C. gloeosporioides (Penz.) Penz. &

Sacc. and C. acutatum J.H. Simmonds,

have been associated with anthracnose

diseases of citrus. These anthracnose

diseases, which include post-harvest anthracnose,

postbloom fruit drop (PFD),

and key lime anthracnose (KLA) are of

great economic importance as postharvest

diseases. However, recent evidence

is suggesting that additional species of

Colletotrichum previously unknown

from citrus are causing diseases of citrus

globally, particularly from the C. boninense

species complex.

Colletotrichum karstii You L. Yang, Zuo

Y. Liu, K.D. Hyde & L. Cai (C. boninense

species complex) has been increasingly

reported from anthracnose symptoms

of citrus worldwide and is often found

to occur in association with other Colletotrichum

spp., particularly C. gloeospo-

Continued on Page 34

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September /October 2019 www.progressivecrop.com 33

one species may be present. Historically,

C. gloeosporioides sensu stricto

has been the only species associated

with anthracnose diseases of citrus in


C. karstii, a ‘New’ Species Associated

With Citrus in California



Continued from Page 33

rioides which generally predominates

within citrus hosts. C. karstii has been

increasingly reported from anthracnose

diseases of other crops including

avocado, mango, and persimmon and

is considered the most common and

widely distributed species of the C.

boninense species complex. Although C.

karstii has been reported from citrus in

China, Italy, and Portugal, in the United

States C. karstii has only been reported

from other host species.



Figure 1. Symptoms of Colletotrichum Dieback. A) Shoot dieback symptoms on

Clementine, B) Gumming symptoms on an infested shoot. C) Branch dieback

symptoms on Clementine. D) Wood discoloration and canker on the wood.

Colletotrichum Symptomology

Recently, unusual disease symptoms

associated with Colletotrichum spp.

have been observed frequently in various

citrus orchards in the San Joaquin

Valley of California (Eskalen, per ob).

Symptoms include leaf chlorosis, twig

and shoot dieback, crown thinning,

wood cankers in branches and in some

cases death of young plants (Figure 1).

Isolations from diseased tissues yielded

typical Colletotrichum species based

on colony morphology but slight differences

also suggested that more than

Recent work by researchers at the

University of California have now

identified C. karstii as a new pathogen

of citrus causing twig and shoot

dieback with or without gumming and

occasionally branch dieback and wood

canker in the Central Valley of California.

Pathogenicity tests on clementine

mandarin also confirmed that C.

karstii is a more aggressive pathogen

of citrus in California compared to

C. gloeosporioides based on in planta

experiments (Figure 2, see page 35).

Based on a survey of samples collected

throughout the Central Valley, this

same research also found that both

species are commonly isolated from

symptomatic tissues and were often

found co-infecting the symptomatic

samples. However, the researchers also

never found other known wood canker

pathogen species of citrus within

the Botryosphaeriaceae and Diatrypaceae

from samples in which both

Colletotrichum species were isolated.

Unlike anthracnose which can cause

twig dieback and is associated with C.

gloeosporioides, this disease is associated

with two species of Colletotrichum

and is not limited to twig dieback

alone but is also associated with shoot

dieback and in some cases, woody

cankers. Taken together, this confirms

C. karstii as a new pathogen of citrus

in California causing a disease distinct

from anthracnose which is caused by

C. gloeosporioides.

The association of C. karstii with

citrus twig and shoot dieback in

California represents a significant

finding since C. karstii appears now

to be a new pathogen of citrus in the

United States. Anthracnose disease of

citrus has mainly been attributed to C.

gloeosporioides and C. acutatum which

34 Progressive Crop Consultant September /October 2019

Mean Lesion Length (cm)

C. karstii C. gloeosporioides Control

Fungal Isolates

Figure 2. Pathogenicity of Colletotrichum spp. on ‘4B’ clementine after 15 months. Vertical

lines represent standard error of the mean.

results were found with

other spore trap studies

in California. Wounding

is also known to predispose

plants to infection by

Colletotrichum and typical

agricultural practices and

the environment in California

citrus groves (pruning,

shearing, wind/sand

damage) give both of these

species the opportunity to

colonize citrus trees. Based

on recent research, symptoms

were observed during

the late spring and summer

months, with no new

symptoms being observed

into fall, winter and early

spring. This suggests that

young, tender tissues developing

in the late spring are

likely necessary for initial

pathogen colonization.

Continued on Page 36

are considered mainly as foliar and

fruit pathogens. Although symptoms of

anthracnose caused by C. gloeosporioides

in citrus include twig dieback, leaf

drop and necrosis on fruits as a postharvest

disease, a progression to shoot

dieback and association with branch

dieback and wood cankers has not been


Although little is known regarding the

epidemiology of C. karstii on citrus,

several environmental factors are likely

important for the dissemination and

progression of this disease. Relative

humidity and precipitation in citrus

orchards in California play an important

role in the epidemiology of Colletotrichum

infection whereby conidia

dispersed by rain and humidity are

conducive to pathogen spread. Our

spore trap study showed that spore trapping

of Colletotrichum species occurred

most frequently during the months with

the highest precipitation (Figure 3),

however Colletotrichum spp. were not

always correlated with rainfall. Similar

September /October 2019



Continued from Page 35

Management Practices for

Colletotrichum Dieback

Currently no strategies exist for the

management of this emerging disease in

citrus. Adherence to cultural practices

recommended for the management of

other canker and dieback pathogens

should be followed. These practices

include maintaining trees in good condition

through appropriate irrigation

regimens and proper fertilization, removal

of infested branches and pruning

debris during dry periods followed by

immediate disposal of infested material,

and sanitizing pruning equipment.

Chemical management using fungicides

is being investigated and these methods

may become part of an integrated pest

management strategy for Colletotrichum

diseases of citrus in California.


Financial support for this project was

provided by the Citrus Research Board

(Project # 5400-152). Plants used for

pathogenicity tests were kindly donated

by Wonderful Citrus. We thank D.

Trannam, R. Yuan, K. Sugino, Q. Douhan,

and our cooperating citrus growers

for assistance in the lab and field.

Comments about this article? We want

to hear from you. Feel free to email us at


Average Temperature (°C)/CFU

Average Temperature (°C)/CFU

Kern Co.


Tulare Co.

Total Precipitation (in)/Average Relative Humidity (%)

Total Precipitation (in)/Average Relative Humidity (%)


Figure 3. Monthly spore trap counts with temperature (°C), precipitation

(mm), and relative humidity (%) for (a) Kern and (b) Tulare counties. Vertical

bars represent total colony forming units (CFU) counted from each citrus

orchard by month. Lines represent average monthly temperature (°C) and

relative humidity (%) and total monthly precipitation (mm).

36 Progressive Crop Consultant September /October 2019

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September /October 2019



Evaluating Biostimulant

and Nutrient Inputs to

Improve Tomato Yields

and Crop Health

BY SURENDRA K. DARA | Entomology and Biologicals Advisor, UCCE

AND ED LEWIS | Head, Department of Entomology, Plant Pathology, and

Nematolody, University of Idaho

California is the leading producer

of tomatoes, especially

for the processing market

(California Department of Food and

Agriculture (CDFA), 2019). Tomato is

the 8th most important commodity in

California valued at $1.05 billion. Processed

tomatoes are ranked 6th among

the exported commodities with a value

of $813 million. While good nutrient

management is necessary for optimal

growth, health, and yields of any crop,

certain products that contain minerals,

beneficial microbes, biostimulants, and

other such products are gaining popularity

as they are expected to improve

crop health and yield, impart soil or

drought resistance, induce systemic

resistance, or improve plant's immune

responses to pests, diseases, and other

stress factors (Berg, 2009; Bakhat et

al., 2018; Chandra et al., 2018; Shameer

and Prasad, 2018). Maintaining

optimal plant health through nutrient

management is not only important

for yield improvement, but also an

important part of integrated pest management

strategy since healthy plants

can withstand pest and disease pressure

more than weaker plants and thus reduce

the need for pesticide treatments.


A study was initiated in the summer

2017 to evaluate the impact of various

treatment programs on tomato plant

health and yield. Processing tomato

Continued on Page 40

Experimental plots, transplanting, and treatment details. All photos courtesy of Surendra K. Dara.

38 Progressive Crop Consultant September /October 2019

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Almond Yield (lbs/acre)






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Continued from Page 38

cultivar Rutgers was seeded on June

7th and transplanted on July 18th,

2017 using a mechanical transplanter.

Monoammonium phosphate (11-52-0)

was applied at 250 lb/ac as a side-dress

on August 7th as a standard for all

treatments. Since planting was done

later in the season, crop duration and

harvesting period were delayed due

to the onset of fall weather. Plots were

sprinkler irrigated daily or every other

day for three to four hours for about

two weeks after transplanting. Drip

irrigation was initiated from the beginning

of August for 12-14 hours each

week and for a shorter period from

mid October onwards.

There were five treatments in the study

including the standard. Each treatment

had a 38 inch wide and 300 foot long

bed with a single row of tomato plants.

Treatments were replicated four times

and arranged in a randomized complete

block design. Different materials

were applied through drip using a

Dosatron injector system, sprayed at

the base of the plants with a handheld

sprayer, or as a foliar spray using a

tractor-mounted sprayer based on the

following regimens.

A 50 foot long area was marked in the

center of each plot for observations.

Plant health was monitored on August

1st, 8th, and 22nd by examining each

plant and rating them on a scale of 5

where 0 represented a dead plant and 5

represented a very healthy plant. Yield

data were collected from October 11th

to December 5th on eight harvest

dates by harvesting red tomatoes from

each plot. On the last harvest date, mature

green tomatoes were also harvested

and included in the yield evaluation.

Data were analyzed using analysis of

variance and Tukey's HSD test was

used for means separation.

Results and Discussion

There was no statistically significant

difference (P > 0.05) in the health of

Continued on Page 41

40 Progressive Crop Consultant September /October 2019







AgSil® 21 at 8.75 fl oz/ac in 100 gal of water through drip (for 30

minutes) every three weeks from July 31st to November 13th (6 times).

AgSil 21 contains potassium (12.7 percent K2O) and silicon (26.5

percent SiO2) and is expected to help plants with mineral and climate

stress, improve strength, and increase growth and yields.

Yeti BloomTM at 1 ml/gallon of water. Applied to the roots of the

transplants one day before transplanting followed by weekly field

application through the drip system from August 7th to November 13th

(15 times). Yeti is marketed as a biostimulant and has a consortium of

beneficial bacteria—Pseudomonas putida, Comamonas testosterone,

Citrobacter freundii, and Enterobacter cloacae. Yeti Bloom is

expected to enhance the soil microbial activity and helps with

improved nutrient absorption.

Tech-Flo®/Tech-Spray® program contained five products that

supplied a variety of macro and micro nutrients. Products were applied

through drip (for 30 min) at the following rates and frequencies in

300gal of water.

1. Tech-Flo All Season Blend #1 1 qrt/ac in transplant water and again

at first bloom on August 28th.

2. Tech-Flo Cal-Bor+Moly at 2 qrt/ac at first bloom on August 28th.

3. Tech-Flo Omega at 2 qrt/ac in transplant water and again on

September 11th (two weeks after the first bloom).

4. Tech-Flo Sigma at 2 qrt/ac on September 11th (two weeks after the

first bloom).

5. Tech-Spray Hi-K at 2 qrt starting at early color break on September

25th with three follow up applications every two weeks.

Innovak Global program contained four products.

1. ATP Transfer UP at 2 ml/liter of water sprayed over the transplants to

the point of runoff just before transplanting. Three more applications were

made through drip (for 30 min) on August 7th and 21st and September

4th. This product contains ECCA Carboxy® acids that promote plant

metabolism and expected to impart resistance to stress factors.

2. Nutrisorb-L at 40 fl oz/ac applied through drip (for 30 min) on 31

July, 14 August (vegetative growth stage), 4 and 18 September, and 2

October (bloom through fruiting). Nutrisorb-L contains poly hydroxyl

carboxylic acids, which are expected to promote root growth and improve

nutrient and water absorption.

3. Biofit®N at 2 lb/ac through drip (for 30 min) on July 31st, August 21st

(three weeks after the first), and September 4th (at first bloom). Biofit

contains a blend of beneficial microbes—Azotobacter chroococcum,

Bacillus subtilis, B. megaterium, B. mycoides, and Trichoderma

harzianum. This product is expected to improve the beneficial microbial

activity in the soil and thus contribute to improved soil structure, root

development, plant health, and ability to withstand stress factors.

4. Packhard at 50 fl oz/ac in 50 gal of water as a foliar spray twice

during early fruit development (on September 11th and 18th) and every

two weeks during the harvest period (four times from October 2nd to

November13th). Contains calcium and boron that improve fruit quality

and reduce postharvest issues.

Continued from Page 40

the plants in August (Figure 1) or in the

overall seasonal yield (Figure 2) among

treatments. The average health rating

from three observations was 3.94 for the

standard, 4.03 for AgSil 21, 4.45 for Yeti

Bloom, 4.38 for Tech-Flo/Spray program,

and 4.35 Innovak Global program.

When the seasonal total yield per plot

was compared, Yeti Bloom had 194.1 lb

followed by, Innovak program (191.5 lb),

AgSil 21 (187.3 lb), the standard (147.4 lb)

and Tech-Flo/Spray program (136.5 lb).

Due to the lack of significant differences,

it is difficult to comment on the efficacy

of treatments, but the yield from AgSil 21

was 27 percent more than the standard

while yields from Innovak program and

Yeti Bloom were about 30 percent and 32

percent higher, respectively.

Studies indicate that plants can benefit

from the application of certain minerals

such as silicon compounds and beneficial

microorganisms, in addition to optimal

nutrient inputs. Silicon is considered as

a beneficial nutrient, which triggers the

production of plant defense mechanisms

against pests and diseases (Bakhat et al.,

2018). Although pest and disease conditions

were not monitored in this study,

silverleaf whitefly (Bamisia tabaci) infestations

and mild yellowing of foliage in some

plants due to unknown biotic or abiotic

stress were noticed. AgSil 21 contains

26.5 percent of silica as silicon dioxide

and could have helped tomato plants to

withstand biotic or abiotic stress factors.

Similarly, beneficial microbes also promote

plant growth and health through improved

nutrient and water absorption and imparting

the ability to withstand stresses (Berg,

2009; Shameer and Prasad, 2018). Beneficial

microbes in Yeti Bloom and Biofit®N

might have helped the tomato plants in

withstanding stress factors and improved

nutrient absorption. Other materials applied

in the Innovak program might have

also provided additional nutrition and

sustained microbial activity.

The scope of the study, with available

resources, was to measure the impact of

various treatments on tomato crop health

Continued on Page 42

Figure 1. Plant health on a 0 (dead) to 5 (very healthy) rating on

three observation dates.

Figure 2. Seasonal total yield/plot from different treatments.

Figure 3. Percent difference in tomato yield between the standard

and other treatment programs.

September /October 2019



Continued from Page 41

and yield. Additional studies with soil

and plant tissue analyses, monitoring

pests and diseases, and their impact on

yield would be useful.

Acknowledgements: Thanks to Veronica

Sanchez, Neal Hudson, Sean White,

and Sumanth Dara for their technical

assistance and the collaborating companies

for product samples or providing

financial assistance.


Bakhat, H. F., B. Najma, Z. Zia, S.

Abbas, H. M. Hammad, S. Fahad, M.

R. Ashraf, G. M. Shah, F. Rabbani, S.

Saeed. 2018. Silicon mitigates biotic

stresses in crop plants: a review. Crop

Protection 104: 21-34. DOI: 10.1016/j.


Berg, G. 2009. Plant-microbe interactions

promoting plant growth and

health: perspectives for controlled use

of microorganisms in agriculture. Appl.

Microbiol. Biotechnol. 84: 11-18. DOI:


CDFA (California Department of Food

and Agriculture). 2019. California

agricultural statistics review 2017-2018.



Chandra, D., A. Barh, and I. P. Sharma.

2018. Plant growth promoting bacteria:

a gateway to sustainable agriculture.

In: Microbial biotechnology in environmental

monitoring and cleanup.

Editors: A. Sharma and P. Bhatt, IGI

Global, pp. 318-338.

Shameer, S. and T.N.V.K.V. Prasad.

2018. Plant growth promoting rhizobacteria

for sustainable agricultural

practices with special reference to biotic

and abiotic stresses. Plant Growth Regulation,

pp.1-13. DOI: 10.1007/s10725-


Comments about this article? We want

to hear from you. Feel free to email us at


For Immediate Release:

Dr. Surendra Dara, entomology and biologicals advisor with the University of California

Cooperative Extension, has been selected for the Distinguished Achievement Award in

Extension from the Entomological Society of America that has more than 7000 members

worldwide. This prestigious national level award recognizes outstanding contributions to

extension entomology. His research and extension program creates innovative solutions for

sustainable crop production and protection, and he reaches out to the agricultural community

locally, regionally, and internationally. Details of this award and Dr. Dara’s credentials,

achievements, and current research efforts can be found on the internet at https://www.

entsoc.org/esa-names-winners-2019-professional-and-student-awards. Dr. Dara’s faculty

profile can be seen at https://ucanr.edu/index.cfm?facultyid=4458



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42 Progressive Crop Consultant September /October 2019

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into the Salt

Tolerance of



USDA-ARS, US Salinity Lab,

Riverside California


University of California Riverside

Good quality water is extremely important for agriculture

throughout the world. However, due to reduced availability

of water and increasing food demands, future use of degraded

waters is evident. One of the major concerns of utilizing degraded

waters for irrigation is their high salt concentration.

Salinity is one of the main abiotic stresses faced by the agriculture

industry. Modest increase of soil salinity level impacts both plant

growth and yield by causing several physiological and biochemical

changes. Based on salt tolerance level plants are classified broadly

in two groups: halophytes and glycophytes. The halophytes have

special mechanisms to tolerate high concentrations of salts and

therefore can grow in saline environments. The majority of plants

(including almonds) are glycophytes and cannot tolerate high salt

concentrations and so grow in soil containing low salts. However,

among glycophytes, salt tolerance level varies tremendously not only

at the species level but also at the variety level within a species. This

variation is directly dependent on the functional status of various

molecular components that play critical roles to protect the plant

during salt stress.

In the initial stages of salinity exposure, a plant faces

osmotic stress, resulting in ion imbalance in cells,

membrane disintegration and reduced photosynthesis.

In addition, osmotic stress in the root sends a

signal throughout the plant causing reprograming

of physiological and molecular activities to initiate

defense response against salinity stress. Slowly ionic

stress develops, leading to accumulation of Na +

Continued on Page 46

44 Progressive Crop Consultant September /October 2019

Figure 1. Evaluation of salinity tolerance of 16 almond rootstocks irrigated with waters of different ion compositions.

Photo courtesy of Devinder Sandhu.

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Continued from Page 44

(sodium ions) and Cl- (chloride ions) in

plant tissues. High ion concentrations

are not only toxic but also interfere with

absorption of essential nutrients by a

plant. High Na + and Cl- levels interfere

in many molecular, biochemical, metabolic

and physiological processes which

could also lead to unnatural senescence

and cell death. For plant species that are

moderately tolerant to salinity, osmotic

stress may play an important role.

However, for species sensitive to salinity

such as almonds, low salt concentration

is able to impose ionic stress that may

reach to an intolerable level, whereas it

may not generate osmotic stress critical

for plant growth. Hence, when studying

salinity stress in almonds, it is important

to focus on responses related to

ionic stress and the exposure to salinity

should be gradual to avoid any osmotic

shock. This also mimics field conditions

in an almond orchard, as during spring

salt moves to subsurface layers due to

the rain and slowly moves to upper

layers during summer, which leads to

gradual increase in root zone salinity.

Due to a continuous increase in cultivated

area under almonds, farmers are

forced to utilize marginal lands with

low quality saline water for irrigation.

In almonds, rootstock plays an important

role in regulating plant growth

in salinity stressed


Hence, the



new almond


tolerant to

salinity is

Due to a continuous increase in

cultivated area under almonds,

farmers are forced to utilize

marginal lands with low quality

saline water for irrigation.

highly desirable. In the last two decades,

several studies focusing on screening

almond rootstocks for salinity tolerance

have been conducted and some

tolerant rootstocks have been identified.

However, a comprehensive approach to

screen and develop new rootstocks with

enhanced salinity is missing in almonds.

Impact of Salinity on Water

Relations and Photosynthesis

Water uptake by a plant is drastically

affected under salinity, which leads to

reduced water potential, relative water

content, stomatal conductance and

transpiration. As plants take nutrients

with water, reduced water uptake also

decreases tissue concentration of essential

nutrients affecting plant growth. In

addition, high salt concentrations also

affect homeostasis, osmoregulation and

net photosynthesis. Photosynthesis is

the most critical metabolic process for

almonds. In response to salinity, osmotic

stress-mediated stomatal closure prevents

water loss through transpiration

in plants that also restricts the amount

of CO2 taken in for photosynthesis.

Consequently, stomatal conductance,

net photosynthetic rate and amount of

chlorophyll are used as physiological

parameters to study salinity tolerance in

different almond varieties. In a recent

study where we compared several

rootstocks for salinity tolerance,

photosynthetic rate was

found to be the most reliable

parameter to assess

salinity tolerance.

Continued on Page 48


Progressive Crop Consultant September /October 2019

Continued on Page 46


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*Patent pending

September /October 2019






Your Edge – And Ours – Is Knowledge.

Continued from Page 46

Tissue Ion Composition

and Salinity Tolerance

Tissue Na concentration is commonly

used as a guide for the salinity tolerance

of a variety. However, for some plant

species, tissue Na concentration is not

a true indicator of salt tolerance of a

variety. Never-the-less, for almonds the

negative correlation between tissue Na

concentration and salt tolerance holds

well. Similar to Na accumulation, salt

tolerant genotypes stored least amount

of Cl in leaf tissue.

Genetic Control of

Salinity Tolerance


Progressive Crop Consultant September /October 2019

In model plants, hundreds of genes

have been discovered that play critical

roles in salinity tolerance. Salt-stress

induced signaling pathways have also

been well-dissected. Molecular mechanisms

of salt tolerance or salt sensitivity

is largely unknown in almonds.

Expression analysis of genes involved in

ion transport in almond tissue showed

induction of multiple genes involved

in Na + and Cl- transport under salinity

treatment, suggesting importance of

both Na and Cl during salinity stress.

The genes involved in Na + transport

were differentially expressed during

salinity stress, compared to the control.

For instance, NHX1 (a vacuolar sodium/proton

antiporter) and SOS3 (SALT

OVERLY SENSITIVE 3 that encodes

a calcium sensor) were upregulated in

leaves and on the other hand HKT1

(encodes a Na transporter) was induced

in roots under salinity treatment. SOS3

is involved in Na + exclusion from roots,

NHX1 plays a role in sequestering Na +

in vacuole and HKT1 is critical for

retrieving Na + from xylem back into

root to protect leaves from salt toxicity.

Additionally, CLC-C (chloride channel

C) and SLAH3 (encodes a slow-type

anion channel) that are important for

Cl- transport, were highly upregulated

in salinity treatments in almond roots.

These observations confirmed the role

of multiple component traits in salt tolerance

mechanism in almonds. As seen

in other plants, multiple signaling pathways

and various genes are expected

to be involved in establishing ionic homeostasis

during salt stress. Nevertheless,

there are not many studies focusing

on understanding the roles of organic

solutes and enzymatic or non-enzymatic

antioxidants in mitigating effects

of salinity in almonds. Although some

genes involved in ion exclusion, and

ion sequestration in vacuoles have been

identified in almonds, future studies are

warranted to identify additional genes.

In addition, different scions should also

be compared for the genetic variation

involved in ion homeostasis and scavenging

reactive oxygen species (ROS)

produced during salinity stress, which

may provide some insights into sensitivity

of almonds to salinity.

Contrary to studying the importance of

a few genes in salinity stress at a time,

an RNA-seq based approach compares

global changes in gene expression between

the control and the salinity treatments.

In addition to targeting genes

already characterized in model plants

this strategy can link different pathways

involved in salinity tolerance and identify

specific almond genes contributing

toward salt tolerance.

Can Alternate Approaches

Mitigate Harmful

Effects of Salinity?

Many additional strategies have been

reported in plants that have been implicated

to improve salt tolerance level

in response to salt stress. For instance,

application of certain microbes could

improve salt tolerance level of plants.

Arbuscular mycorrhizal fungi (AMF)

are known to form symbiotic associations

with many land plants that

are considered to be valuable to plant

growth. AMF helps host plants not only

by providing essential minerals but also

by impeding the translocation of

toxic ions like sodium. The use

of AMF in multiple plant

species has shown

enhanced growth,


and productivity


salt stress. Although, different Prunus

rootstocks have been screened for mycorrhizal

colonization, direct effect of

AMF in mitigating salinity still need to

be established.

Application of plant growth promoting

rhizobacteria (PGPR) is also known

to improve salt tolerance in different

plant species. However, there are no

published reports describing the effect

of PGPR in improving salt tolerance in


Although, AMF and PGRP show a lot

of promise, the potential of their application

on almond rootstocks to mitigate

salinity stress needs to be explored further,

along with the economic feasibility

of these approaches at the commercial


Future Perspectives

One of the main consequences of the

climate change is the length and frequency

of drought periods experienced

in certain parts of the world. California,

the main almond producing region of

the world, experienced a long drought

period in the recent past. Drought leads

to excessive groundwater pumping and

use of alternative water resources with

high salinity for irrigation. Based on

the current trends, salinity problem is

expected to intensify in next couple of

decades. Currently, salinity screening is

taking a backseat in almond rootstock

breeding, which is expected to change

in the near future. One of the approaches

for the future almond breeding

programs will require screening of wild

genetic material for salinity

tolerance. In addition

to the other



stock traits such as high vigor, nematode

resistance, disease resistance, insect

resistance, drought tolerance, salinity

tolerance should also take central stage

during rootstock breeding.

Identification and isolation of the key

almond genes involved in salinity

tolerance will be critical. Functional

validation of selected almond genes

by complementation assay in a model

plant like Arabidopsis may provide an

initial proof of functional conservation

of genes between these species.

Characterization of genes will facilitate

identification of specific mutations that

are critical for salinity tolerance. The

CRISPR/Cas9 system has a great potential

in fixing the both type of genes

that play positive or negative roles in

salt tolerance in almonds. The CRISPR/

Cas9 is a precise, suitable, and efficient

technology that has been used for

genome editing in various crops such

as rice, wheat, maize and sorghum. It

is important to note that CRISPR/Cas9

modified crops are not considered as

genetically modified organisms (GMO).

Identification and characterization of

genes regulating ion uptake, effective

compartmentalization, and tissue tolerance

may provide new means to develop

almond varieties with enhanced salinity



The study was funded by Almond Board

of California.

“ One of the main consequences of the

climate change is the length and frequency

of drought periods experienced

in certain parts of the world.

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Tim Peltzer

Peltzer Farm Management

Terra Bella, CA

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September /October 2019



The Crop Consultant


Full Menu of Workshops and Seminars


The inaugural Crop Consultant

Conference (CCC) will be a

gathering place for all who are

dedicated to caring for California

specialty crops.

Pest Control Advisors (PCA), Certified

Crop Advisors (CCA), applicators and

agriculture retailers are all invited to

participate in this two-day conference,

September 26-27 in Visalia.

This event at the Visalia Convention

Center packs a full menu of educational

workshops and seminars, professional

networking opportunities plus multiple

hours of PCA and CCA credits into 24

hours. The program begins at 1 p.m. on

Thursday and concludes after lunch and

a final speaker, at 1 p.m. on Friday.

The workshop and seminar topics at the

CCC have been chosen to help all crop

advisors keep informed about new regulations,

pest and disease control and

management updates, label information

and new technologies. In addition

to the educational component, this

conference will feature an early evening

mixer and networking opportunities

to be followed by a full gala dinner and


Why Attend?

“Where else can a PCA or CCA get that

many hours of credit, receive useful

information plus meals and entertainment

and not have to drive long distances?”

says Jason Scott, publisher

of West Coast Nut, Progressive Crop

Consultant and Organic Farmer

magazines and host of this conference.

“This event is right in their

back yard, where specialty

crops addressed in this

conference, are grown. It

is designed to present

the ‘big picture’

of specialty crop

production, innovative

technology, regulations,

and challenges here in California,” Scott



Greg Douhan University of California

Cooperative Extension (UCCE) area

citrus advisor for Tulare, Fresno and

Madera counties, said the conference

will be a valuable forum to communicate

important research and information

regarding many aspects of various

50 Progressive Crop Consultant September /October 2019

crops grown in California.

Agriculture industry

personnel, PCAs, CCAs,

and so on and so forth,

benefit from these

meetings tremendously

to keep abreast of the

latest challenges that face

California Agricultural


Douhan, whose territory includes a

major portion of California’s citrus belt,

will be one of the featured conference

speakers and will present current information

on HLB and Asian Citrus Psyllid


Aerial Drone Technology

A presentation on aerial drone technology

is also expected to drive attendance.

Chris Lawson, Business Development

Manager for Aerobotics, will speak on

optimizing integrated pest management

(IPM) and nutrient management using


Agronomist Nick Canata with Ingleby

USA/Eriksson LLC of Visalia reports

that the CCC agenda looks interesting,

especially the drone technology presen-

This event is right in their

back yard, where specialty

crops addressed in this

conference are grown. It

is designed to present the

‘big picture’ of specialty

crop production, the new

technology, regulations

and challenges here in


Continued on Page 52

September 26th-27th

Visalia Convention Center

See pages 54-55 for more details or visit


September /October 2019



Botrysphaeria on walnut. Photo courtesy of Cecilia


Checking for NOW Larvae. Photo courtesy of

Cecilia Parsons.

Continued from Page 51

tation. His company, he added, is presently

using aerial flyovers to obtain irrigation


Mating Disruption

Crop advisors who are evaluating their mating

disruption choices will hear a panel of experts

that includes United States Department of

Agriculture (USDA) researcher Chuck Burks,

Dani Casado, chemical ecologist with Suterra

and Peter McGhee, research entomologist

with Pacific BioControl Corp. This panel will

evaluate mating disruption as part of an IPM



Thursday’s program starts on the ground with

sustainability specialist Richard Kreps who

will explain how to get the most out or your


Kreps, with Ultagro, said making soils work

at an optimal level requires a quite a bit of

dedication. Attacking it from all sides: amending,

nutrition applications, increasing organic

matter, biology and proper irrigation require

a lot of coordination. The upside is orchard

longevity, higher returns with less disease and

pest pressure.

Paraquat Guidelines

Thursday’s education agenda ends with new

EPA guidelines for 2020 for Paraquat closed

transfer system. Speaker will be Charlene Bedal,

West Coast regional manager with Helm


Trade Show and Mixer

The conference mixer and trade show begin

at 5 p.m. Thursday, and dinner will be served

at 6 p.m. The keynote speech will be Trécé on

NOW Monitoring and Management–Current

and Future Trends. At 7, Las Vegas entertainer

and illusionist Jason Bird will perform. One

of the most innovative and prolific minds in

the magic industry, Bird continuously advances

the boundaries of his craft while making

connections with his audiences. Bird will also

perform small group illusions during the trade



Friday morning’s agenda kicks off at 7 a.m.

with breakfast and a presentation by Patty

Cardoso of Gar Tootelian on keeping growers

compliant with local and state regulations. The

trade show opens at 7:30.

Friday’s topics include A New Approach to

IPM by Surendra Dara, UCCE entomologist;

a panel discussion major crop pests affecting

specialty crops; and an update on labels.

To register for this event and see a complete

agenda, go to


Comments about this article? We want

to hear from you. Feel free to email us at


52 Progressive Crop Consultant September /October 2019

September 26th-27th

Visalia Convention Center

Pre-Register at


Find the full agenda

on page 55

or online at


September /October 2019



PCA Credit

CCA Credit

ve and

er –


pliance for



Label Update

CE Credits: 50 Minutes; L & R

powered by:


Evaluation of Mating

Disruption as Part of an IPM


Chuck Burks USDA

Dani Casado, Ph.D. in Applied Chemical Ecology, Suterra

Peter McGhee, Ph.D., Research Entomologist

CE Credits: 40 Minutes; Other

Powered by:






Regulatory Impacts on

California Crop Protection


September 26th-27th

Visalia Convention Center

303 E. Acequia Ave. Visalia, CA 93291


Trade Show

CE Credits: 30 Minutes; Other


Panel—Top Insects Plaguing

California co-hOSTED Specialty By: Crops—

BMSB, Mealy Bugs/NOW

Spotted Wing Drosophila

David Haviland (Mealy Bugs/NOW) UC

Cooperative Extension, Kern County,

Kent Daane (SWD) Cooperative

Extension Specialist, UC Berkeley,

Jhalendra Rijal (BMSB) UCCE IPM

Advisor for northern San Joaquin Valley

CE Credits: 60 Minutes; Other




A New Approach to IPM

Western Growers

FOR MORE DETAILS OR TO PRE-REGISTER ONLINE Surendra VISIT Dara, Entomology and Biologicals Advisor,

University of California Cooperative CE Credits: 30 Minutes; L & R





Dinner Sponsor

Mixer Co-Sponsor

CE Credits: 30 Minutes; Other OVER $1,000 VALUE



Agenda Sponsor Indoor Sponsor Registration Sponsor

PCA Hours:

CCA Hours:

ONLY $100

per person

Workshops and Seminars

Mixer & Networking

Meals Included

(Breakfast, Lunch and Snacks)

Full Gala Dinner

Live Entertainment

(Jason Bird, Magician and Illusionist)

Over 60 Exhibits





September 26th

1:00PM - 9:00PM

September 27th

7:00AM - 1:15PM

Coffee Sponsor

Traeger Grill Sponsor



Helping Farmers Grow NATURALLY Since 1974

Indoor Sponsor

Breakfast Sponsor

Break Sponsor

Indoor Sponsor

Indoor Sponsor

Lanyard Sponsor

Indoor Sponsor

54 Progressive Crop Consultant September /October 2019

Tote Bag Sponsor

Mixer Co-Sponsor

CE Credit Sponsor


September 26




Getting the Most out

of Your Soil

Richard Kreps, CCA


How to Optimize IPM and

Nutrient Management using

Aerial Drone Technology

Chris Lawson, Business Development Manager, Aerobotics

CE Credits: 30 Minutes; Other


Managing Botrytis in a

Challenging Year

Gabriel Torres, UCCE Farm Advisor, Tulare County

CE Credits: 30 Minutes; Other


The Latest in HLB and Asian

Citrus Psyllid Management

Greg Douhan, UCCE Area Citrus Advisor for Tulare,

Fresno, and Madera Counties

CE Credits: 30 Minutes; Other


Navigating Fungal Diseases

Themis Michailides , Professor and

Plant Pathologist UC Davis

CE Credits: 30 Minutes; Other


Paraquat Closed Transfer

System (New EPA

Guidelines for 2020)

Charlene Bedal, West Coast Regional


CE Credits: 30 Minutes; L & R


Mixer/Trade Show

CE Credits: 30 Minutes; Other




NOW Monitoring and

Management – Current and

Future Trends

Brent Short, Regional Technical

Representative, Trécé, Inc.

CE Credits: 30 Minutes; Other


Jason Bird

Magician and Illusionist

Jason Bird will perform small group illusions

during the trade show / mixer from 5-6PM


September 27


Breakfast / Going Above and

Beyond for Your Grower –

Keeping them Compliant

Patty Cardoso, Director of Grower Compliance for

Gar Tootelian, Inc.


Trade Show


Label Update

Plant Food Systems, Inc., Trécé, Inc., Helm, Suterra,

& Sym-Agro, Inc.

CE Credits: 60 Minutes; L & R

September /October 2019


Update on the Sterile Insect

Program for NOW

Houston Wilson, Asst. Coop. Extension Specialist,

Kearney Ag. Center, Dept. Entomology, UC Riverside

CE Credits: 30 Minutes; Other


Trade Show Break

CE Credits: 30 Minutes; Other




Evaluation of Mating

Disruption as Part of an IPM Program

Chuck Burks USDA

Dani Casado, Ph.D. in Applied Chemical Ecology, Suterra

Peter McGhee, Ph.D., Research Entomologist

CE Credits: 30 Minutes; Other


Panel—Top Insects Plaguing

California Specialty Crops—

BMSB, Mealy Bugs, NOW,

Spotted Wing Drosophila

David Haviland (Mealy Bugs/NOW) UC

Cooperative Extension, Kern County,

Kent Daane (SWD) Cooperative

Extension Specialist, UC Berkeley,

Jhalendra Rijal (BMSB) UCCE IPM

Advisor for northern San Joaquin Valley

CE Credits: 60 Minutes; Other




Label Update



A New Approach to IPM

Surendra Dara, Entomology and Biologicals Advisor,

University of California Cooperative Extension

CE Credits: 30 Minutes; Other








Apply High Phos as Part of Your Post Harvest Fertilizer Program.

A balanced formulation of essential nutrients containing

organic and amino acids to stabilize the nutrients and

facilitate their chelation, uptake, translocation and use.

56 Progressive Crop Consultant September /October 2019

For more information visit wrtag.com, or

contact Joseph Witzke at (209) 720-8040

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