01_PCC_JanuaryFebruary_2022

January / February 2022 

Review of Rhizoctonia Diseases of Row Crops 

CCA of the Year Keith Backman 

VINEYARD REVIEW 

Use of Gypsum to Reclaim Salt Problems 

in Soils 

Diagnosing Vineyard Problems 

A New Biocontrol Approach for the 

Reduction of Pierce’s Disease in Vineyards 

Volume 7: Issue 1

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IN THIS ISSUE 

Review of Rhizoctonia 

Diseases of Row Crops 

VINEYARD REVIEW 

4 

PUBLISHER: Jason Scott 

Email: jason@jcsmarketinginc.com 

EDITOR: Marni Katz 

ASSOCIATE EDITOR: Cecilia Parsons 

Email: article@jcsmarketinginc.com 

PRODUCTION: design@jcsmarketinginc.com 

Phone: 559.352.4456 

Fax: 559.472.3113 

Web: www.progressivecrop.com 

10 

CCA of the Year Keith 

CONTRIBUTING WRITERS & INDUSTRY SUPPORT 

Backman Recognized 

Luca Brillante 

Frank Martin 

at Crop Consultant 

Bronco Wine Co. Chair & Research Plant Pathologist, 

Conference 

Assistant Professor of 

Viticulture, Department of 

USDA-ARS 

Viticulture & Enology, 

California State University, 

Fresno 

14 

18 

Leaf Sap Analysis: 

A Forward-Looking 

Alternative to Tissue 

Sampling 

Soil Microbes are Key 

Partners for Drought 

Management 

Matthew Fidelibus 

Extension Viticulturist, UC 

Davis 

Sean Jacobs 

Technical Sales and 

Marketing Representative, 

Agro-K Corp., Contributing 

Writer 

Anika Kinkhabwala 

Ph.D., Principal Scientist, A&P 

Inphatec 

Steven Koike 

Director, TriCal Diagnostics 

Khushwinder Singh 

Graduate Research 

Assistant, Department 

of Viticulture & Enology, 

Fresno State University 

Stephen Vasquez 

Technical Viticulturist, Sun- 

Maid Growers 

Dr. Karl Wyant 

Vice President of Ag 

Science, Heliae® Agriculture, 

Chair Western Region CCA 

Board of Directors 

George Zhuang 

UCCE Viticulture Farm 

Advisor, Fresno County 

22 

28 

32 

Use of Gypsum to 

Reclaim Salt Problems in 

Soils 

Diagnosing Vineyard 

Problems 

A New Biocontrol 

Approach for the 

Reduction of Pierce’s 

Disease in Vineyards 

28 

UC COOPERATIVE EXTENSION 

ADVISORY BOARD 

Surendra Dara 

UCCE Entomology and 

Biologicals Advisor, San Luis 

Obispo and Santa Barbara 

Counties 

Kevin Day 

UCCE Pomology Farm Advisor, 

Tulare and Kings Counties 

Elizabeth Fichtner 

UCCE Farm Advisor, 

Kings and Tulare Counties 

Steven Koike 

Tri-Cal Diagnostics 

Jhalendra Rijal 

UCCE Integrated Pest 

Management Advisor, 

Stanislaus County 

Mohammad Yaghmour 

UCCE Area Orchard Systems 

Advisor, Kern County 

40 

Delayed Spring 

Growth and Grapevine 

Production During 

Drought 

40 

Katherine Jarvis-Shean 

UCCE Orchard Systems 

Advisor, Sacramento, Solano 

and Yolo Counties 

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

in this publication are the professional opinions of writers 

and advertisers. Progressive Crop Consultant does not assume any 

responsibility for the opinions given in the publication. 

January / February 2022 www.progressivecrop.com 3

Review of Rhizoctonia 

Diseases of Row Crops 

By STEVEN KOIKE | Director, TriCal Diagnostics 

and FRANK MARTIN | Research Plant Pathologist, USDA-ARS 

The soilborne fungus Rhizoctonia 

is an extremely important pathogen 

of plants worldwide. Hundreds of 

vegetable, field, fruit and nut, and ornamental 

crops are susceptible to this fungus. 

Rhizoctonia is common and severe 

on cereals and herbaceous row crops 

but can also cause disease on woody 

species. Found in soils throughout the 

world, this pathogen has evolved survival 

strategies that enable it to become 

established wherever it is introduced. 

Despite the implementation of integrated 

pest management tools, Rhizoctonia 

remains a challenging pathogen that is 

difficult to control. 

Understanding Rhizoctonia solani 

Rhizoctonia is the genus name that 

refers to a group or “complex” of fungi. 

Initially, fungal species were placed in 

this Rhizoctonia group because they 

shared certain features, such as the 

absence of asexual (anamorph) spores 

(remember that fungi can have two 

different phases or forms: asexual and 

sexual); a sexual (teleomorph) stage 

belonging to the Basidiomycetes; distinctive 

cell wall structures (septa) that 

divide the relatively thick hypha into 

sections, an existence that is primarily 

in the soil; and being mostly pathogenic 

to plants. For most row crops, 

the species Rhizoctonia solani is the 

most important pathogen. 

Rhizoctonia is considered a “species 

complex” because of the many closely 

related species and subspecies that 

make up this group. Figure 1 outlines 

and breaks down this complicated, 

diverse group of organisms. The 

Rhizoctonia genus, first of all, can be 

divided into two major categories: (A) 

Those species that have two nuclei per 

mycelial cell (called binucleates) and 

(B) those species that have more than 

two nuclei per cell (multinucleates). R. 

solani and other species (e.g., R. oryzae 

and R. zeae) are in the multinucleate 

Rhizoctonia solani most often attacks the belowground 

parts of plants, such as these cauliflower crowns, resulting 

in loss of root attachment and decline of the plants 

(all photos by S. Koike.) 

Rhizoctonia solani forms tiny, matted mycelial clumps 

(sclerotia) that enable the pathogen to survive in soil 

for prolonged periods. 

group. Note that each fungus listed in 

Figure 1 has two taxonomic names. 

The Rhizoctonia name refers to the 

anamorph or asexual stage and is the 

phase of the fungus that infects plants 

Continued on Page 6 

1 2 3 4 5 

"Rhizoctonia" Examples of Rhizoctonia species Examples of anastomosis Isolates within AGs can be 

refers to a diverse There are two main in each group, along with the groups (AGs) in R. solani and further differentiated 

species complex groups of Rhizoctonia teleomorph (sexual stage) name disease tendencies based on physiology 

and genetic traits 

A. Binucleate: mycelial Rhizoctonia cerealis (Ceratobasidium cerealis) 

cells have two nuclei 

AG1: seed infection, hypocotyl 

Rhizoctonia 

Rhizoctonia solani (Thanatephorus cucumeris) 

rot, aerial web blight 

B. Multinucleate: mycelial 

cells have more than 2 

Rhizoctonia oryzae (Waitea circinata) 

AG2-1: root crop canker, 

crucifer wire stem 

nuclei 

Rhizoctonia zeae (Waitea circinata) 

AG2-2/IIIB and AG2-2/IV: 

turfgrass brown patch, sugarbeet 

root disease 

AG3: affecting mostly potato 

Growth rates 

Thiamine metabolism 

Growth on carbon sources 

rDNA-ITS genetic sequences 

AG4: infects many crops 

AG8: mostly on cereals, also 

infects potato roots 

There are currently 14 AGs 

for Rhizoctonia solani 

Figure 1. Complexity of the plant pathogenic Rhizoctonia group, and placement of R. solani. 

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Continued from Page 4 

and causes disease. The second name 

is the teleomorph or sexual stage. This 

form is rarely found in the field and 

probably does not cause disease in 

plants; however, researchers employ the 

teleomorph names when studying the 

interrelationships between the various 

species. Our challenging fungal foe is 

therefore known mostly as Rhizoctonia 

solani (anamorph) but is also referred 

to as Thanatephorus cucumeris (teleomorph). 

The R. solani species is itself very diverse 

and can be separated into distinct 

groups. Different isolates of R. solani 

fall into one of many anastomosis 

groups, or AGs (Figure 1, see page 4). 

AGs are determined in the laboratory 

where two isolates are grown sideby-side 

in culture and the resulting 

reaction, whether the two hyphae fuse 

(compatible) or do not fuse (incompatible), 

is viewed under the microscope. 

Isolates that are deemed compatible 

are placed together into a numbered 

AG. Incompatible isolates cannot be 

in the same AG. There are currently 14 

AGs: AG1 through AG13, and AGB-1. 

Seven of these AGs are further divided 

into subgroups. Molecular techniques 

are also available for AG classification; 

such techniques can be more accurate 

than searching for hyphal fusion under 

the microscope. Molecular methods, 

however, can be time-consuming to 

complete. 

For lettuce and other head forming row crops, Rhizoctonia solani can cause a rot where the 

basal leaves are in contact with soil. 

Rhizoctonia disease 

category 

Seed decay 

Preemergent 

damping-off 

Post-emergent 

damping-off 

Root rot of young plants 

Stem canker of 

young plants 

Foliar blight 

Bottom rot 

Fruit and pod rot 

Decay of fleshy tubers 

and roots 

Categorizing R. solani isolates into 

these AGs is not an academic exercise 

but provides insights into how this 

pathogen functions in agriculture. 

Different AGs possess different traits; 

while some AG isolates have a broad 

host range, others are more restricted 

regarding the crops they can infect. For 

example, R. solani AG2-1 tends to be 

the main pathogen that causes wirestem 

on crucifers, while AG2-2/IIIB 

and AG2-2/IV cause brown patch in 

turfgrass and root disease on sugarbeet. 

R. solani AG3 is common on potato 

and causes stem and stolon lesions as 

well as black scurf on tubers. R. solani 

AG8 is primarily a pathogen of cereals 

but also infects potato roots. In contrast, 

AG4 has a broad host range and 

can infect many crops. So, identifying 

the AG status of an R. solani isolate can 

provide important information on the 

diseases caused by that isolate and the 

susceptibility of subsequent crops that 

might be placed in that field. 

Finally, isolates belonging to the same 

AG are not all identical to each other. 

While sharing the same AG designation, 

the isolates can differ physiologically 

in how carbon sources and 

other chemicals are metabolized, how 

Targeted plant tissue 

Seed planted in the ground is invaded and rotted 

before the seed germinates. 

Seed germinates; root and shoot are infected and 

killled before seedling shoot emerges above ground. 

Seed germinates and plant emerges above ground; 

root, crown, and lower stem are infected and plant 

collapses and dies. 

Young plants are healthy while germinating and 

emerging; after plant establishment, roots become 

infected and develop brown lesions. 

Young plants are healthy while germinating and 

emerging; after plant establishment, crown and lower 

stem tissue in contact with soil becomes infected and 

develops sunken, brown cankers. 

Aboveground leaves, stems, shoots become diseased 

when the pathogen is splashed up onto foliage. 

For head-forming crops (lettuce, cabbage), bottom 

leaves in contact with soil develop brown lesions that 

later advance into extensive rots. 

Fruits (e.g., cucurbit, tomato) and pods (e.g., bean, 

pea) in contact with soil develop lesions and rots. 

Fleshy underground vegetables such as sweet potato 

roots and potato tubers become infected and develop 

various symptoms. 

Table 1. Categories of Rhizoctonia solani diseases of row crops 

fast they grow in culture, and other 

features. Isolates in the same AG can 

also differ genetically and have varying 

DNA sequences. This great diversity 

found within R. solani isolates accounts 

for the difficulty that researchers have 

in fully understanding this important 

plant pathogen complex. 

Diverse Diseases Caused 

by Rhizoctonia solani 

Rhizoctonia solani causes different 

types of crop diseases, all of which 

are related to the soilborne nature of 


Rhizoctonia is one of the damping-off pathogens 

that can affect young seedlings, such as the Swiss 

chard plants pictured here: infected plants (left), 

healthy plants (right). 

this pathogen (Table 1, see page 6). R. 

solani can be a seed pathogen. Once 

seed are placed in the ground, R. solani 

that is residing in the soil can invade 

the seed and kill it before it germinates. 

Even if the seed germinates, R. solani 

can cause a decay of the roots and 

shoots before the seedling emerges 

above the soil surface; this early seedling 

disease stage is called preemergent 

damping-off. Post-emergent damping-off 

occurs if the diseased seedling 

is strong enough to grow above the soil 

surface, only to succumb and collapse 

shortly afterwards (Table 1). Collectively, 

seed decay, preemergent damping-off 

and post-emergent damping-off can 

result in loss of plants very early in the 

production cycle, causing stand loss in 

the field. Healthy seedlings that escape 

death at the seed and newly germinated 

stages remain vulnerable to this pathogen; 

established seedlings can still be 

infected by R. solani and develop root 

rots and/or lesions on stems in contact 

with soil (Table 1). 

Plant leaves are not immune to R. 

solani. Field cultivation practices and 

splashing water can move bits of R. 

solani-infested soil up into the foliage 

of plants. Under favorable conditions, 

the introduced R. solani mycelium can 

colonize the leaf tissue and cause foliar 

blights in crops such as endive (Table 

1). For head-forming vegetables such as 

lettuce and cabbage, the bottom leaves 

are unavoidably in direct contact with 

the soil. If R. solani is present in the 

underlying soil and if conditions (excess 

soil moisture) favor the pathogen, 

extensive rotting of the lower leaves 

Rhizoctonia solani-contaminated soil particles 

can be moved up onto the leaves, causing a 

foliar blight on crops such as endive. 

and plant base can take place, resulting 

in bottom rot. If fruits (e.g., cucumber) 

and pods (e.g., beans) happen to 

be in contact with infested soil, these 

harvestable commodities can become 

diseased (Table 1). Finally, sweet potato 

roots, potato tubers and other similar 

plant structures under the ground can 

suffer from lesions, rots, and defects 

from R. solani in the soil surrounding 

these fleshy plant parts. Table 2 lists 


Row crop hosts 

of Rhizoctonia 

solani 

Asparagus 

Bean 

Beet 

Broccoli 

Broccoli rabe 

Cabbage 

Carrot 

Celery 

Cauliflower 

Chinese cabbage 

Cilantro 

Cucurbits 

Endive 

Hemp 

Lettuce 

Pea 

Potato 

Radish 

Spinach 

Sweet potato 

Swiss chard 

Tomato 

Disease 

crown rot 

crown and root rot 

damping-off 

wirestem 

crown rot 

bottom rot 

root canker 

crater rot 

wirestem 

bottom rot 

root rot 

damping-off 

leaf blight 

root rot 

bottom rot 

foot rot 

Stem & stolon canker, 

tuber black scurf 

root rot 

root and petiole rot 

stem canker 

damping-off 

damping-off 

Table 2. Row crop hosts of Rhizoctonia 

solani. 



some row crops that are susceptible to 

R. solani. 

Disease Development 

Rhizoctonia solani has evolved to be a 

challenging, persistent soilborne pathogen. 

Tiny, tightly clustered clumps 

of mycelium grow together to form 

resilient structures (sclerotia) that can 

withstand unfavorable conditions and 

allow it to survive for years without a 

plant host. These sclerotia are the main 

mechanism for survival, since R. solani 

is not a particularly aggressive or successful 

saprophyte in the soil environment. 

When a host plant grows next to 

sclerotia and favorable soil conditions 

are present, the dormant mycelium 

germinates and can infect the plant. 

Diagnostic Considerations 

Diagnosing Rhizoctonia diseases based 

only on symptoms is risky because 

Rhizoctonia is not the only soilborne 

pathogen that causes seedling damping-off, 

root rots and stem lesions of 

row crops. On spinach, damping-off 

and root rot can be caused by R. solani, 

Fusarium and Pythium; visually, one 

cannot reliably distinguish between 

the symptoms caused by these three 

pathogens. Cilantro crops can develop 

similar-looking root diseases caused 

by R. solani and Fusarium. Cauliflower 

transplants are susceptible to both 

Rhizoctonia and Pythium, both of 

which cause the lower stem tissue to 

become discolored. Cauliflower disease 

diagnostics is further complicated 

because the root maggot insect feeds on 

lower stem tissue and causes symptoms 

identical to those created by R. 

solani. Precise and accurate diagnosis 

of Rhizoctonia diseases will therefore 

require lab-based examination and 

assays. Diagnosticians usually deploy 

culture tests in which surface sanitized 

bits of symptomatic tissues are placed 

in microbiological agar media. These 

scientists then use microscopes to examine 

the mycelium that grows out of 

the plated tissue. For most fungi, spores 

When testing plants, diagnostic labs use microscopes to look for the brown, relatively broad, 

distinctive branching mycelium that characterizes Rhizoctonia solani. 

are important structures that diagnosticians 

rely on for fungal identification; 

since R. solani produces no spores, 

scientists must examine the hyphal 

structures or employ molecular assays 

to confirm this pathogen. 

Managing R. solani 

Rhizoctonia is a difficult pathogen to 

control. Attempts to manage this fungus 

will require the implementation of 

IPM practices. 

Site Selection Plant in fields that do not 

have a history of Rhizoctonia problems 

and that have well-draining soils. 

Crop Rotation Avoid planting a susceptible, 

sensitive crop in a field known 

to have significant problems with this 

pathogen. Rotate to crops that are either 

not susceptible or are less sensitive 

to damage caused by R. solani. Remember 

that some R. solani AG isolates have 

a very broad host range and can infect 

many row crops; however, other AG 

isolates show some level of host specificity 

and are pathogenic on only a few 

crops. It is therefore useful to know 

which AGs are present in the field. 

Time of Planting In some cases, moving 

the planting date to a different time 

of year may help reduce losses from R. 

solani. Planting the crop in the warmer, 

drier part of the year allows the seedling 

to grow more rapidly and perhaps 

escape or minimize infection from R. 

solani. 

Fungicides Plant seed treated with a 

fungicide.Note that the seed treatments 

used to protect against Pythium have 

little effect on Rhizoctonia. Fungicides 

applied to emergent plants have little 

benefit. 

Resistant or Tolerant Cultivars There 

do not appear to be row crop cultivars 

that have genetic resistance to Rhizoctonia. 

However, if young seedlings escape 

infection early in development, the 

maturing stem tissue will later become 

resistant to infection by R. solani. 

Sanitation Remember that as a soilborne 

pathogen, R. solani will be 

moved and spread via mud adhering to 

tractors and equipment. Prevent the introduction 

of R. solani into plant nursery 

and transplant facilities by using 

new or thoroughly sanitized containers 

and trays, disposing of used rooting 

media and other sanitation measures. 

Comments about this article? We want 

to hear from you. Feel free to email us at 

article@jcsmarketinginc.com 


® 

IMAGINATION 

INNOVATION 

SCIENCE IN ACTION 

 

 

 

 


CCA of the Year 

Keith Backman 

Recognized at 

Crop Consultant 

Conference 

Award celebrates agronomists’ five decades of 

commitment to industry and community. 

By MARNI KATZ | Editor 

Western Region CCA Past Chairman Jerome Pier, left, 

presented Backman with the CCA of the Year award at 

the Crop Consultant Conference in September. 

T 

his year’s Western Region CCA 

Crop Consultant of the Year, Keith 

Backman, has been advising farmers 

in the San Joaquin Valley since the 

mid-1970s on fertilizer and irrigation 

management and the wisdom of matching 

those nutrient and water applications 

to the needs of the crops. Today, in 

an environment of increased regulation 

and costs related to fertilizer inputs, that 

prudence has grown more and more 

important. 

Backman went to work with Nat Dellavalle 

out of college in the 1970s and 

has been with Dellavalle Laboratory in 

one way or another ever since. Today, 

he splits his time in semi-retirement 

between traveling with his wife Gail 

and imparting his wisdom on plant 

nutrition and water analysis to a new 

generation of agronomists as part owner 

of Dellavalle Labs. 

Jerome Pier, outgoing Chairman of the 

Western Region CCA announced Backman 

as the winner of the new CCA of 

the Year Award at this year’s Crop Consultant 

Conference in Visalia this past 

September. Pier said Backman sets the 

standard for the region’s 1,300 CCAs 

for his contributions to plant nutrition 

and soil science over his 40-year career 

and his contributions to the industry. 

“He’s made a big impact on a lot of 

people in the Central Valley and on 

Central Valley ag for sure,” Pier said. 

“His understanding of nutrition in permanent 

crops is world class.” 

Backman is known for having an 

advanced understanding about taking 

and interpreting soil tests, and making 

preplant and in-season recommendations 

for fertility and irrigation management 

that are well suited to crop 

needs and soil status while also being 

environmentally sound. 

Career of Service 

As a member of the Western Plant 

Health Association’s Soil Improvement 

Committee for more than 20 years, 

Backman helped write the chapters on 

irrigation management and nitrogen 

management for the revised editions of 

the Western Fertilizer Handbook. The 

latest edition was just released and has 

Backman’s expertise throughout. 

He was also in on the ground floor of 

developing nitrogen management plans 

and was instrumental in drafting nitrogen 

budgeting and checkbook methods 

that have been adopted for nitrogen 

management plans by water quality 

coalitions. 

“He basically authored these nitrogen 

management plans, and without those 

plans agriculture was going to get shut 

down by environmental activists,” Pier 

said. “This was the only way to show 

a good faith effort that we are doing 

something about it.” 

Those principals are based on the 

relationship between nutrient and water 

management. 

“Over the years I’ve come to realize that 

so many of our deficiencies are irrigation 

related,” Backman said. “Especially 

with nitrogen, you can’t have a good 

accurate nitrogen program unless you 

have an accurate irrigation program.” 

Farmers and PCAs today have a much 

clearer understanding about the timing 

of fertilizer applications and rates at 

those particular times, he said. 

Where growers might have done a single 

or split application of 150 pounds 

of N fertilizer a year, for instance, they 

now make multiple applications based 

on yield estimate, soil conditions, crop 

timing and soil and leaf analysis. 

“This is where the CCA earns their 

money is helping a grower understand 

that,” Backman said. “Growers can’t 

guess anymore. They need proven solu- 



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tions and so more and more they are 

relying on the diagnosis of a CCA.” 

Humble Ag Roots 

Raised on a small farm south of Yuba 

City, Backman was seventh out of 

eight children in an agricultural 

family. While getting a Master’s degree 

in pomology at UC Davis, Backman 

focused his studies on boron toxicity 

in orchard crops. This is a problem that 

became more of an issue as deep-rooted 

permanent crops went in up and 

down the Valley and water shortages 

made leaching out of those root zones 

more difficult. 

He worked early on in his college 

career under Kay Uriu, a professor in 

the UC Davis pomology department 

in the 1970s, who did ground-breaking 

research on tree nutrition status 

and was known for being able to spot 

nutrition imbalances by looking into 

an orchard. 

As a result, Backman said even today 

he “can’t help driving by an orchard 

and looking at it and thinking ‘what 

can I do to get it growing more efficiently?’” 

In addition to his service for the industry, 

Backman has been a scout master 

in his community for more than 20 

years and until recently was an active 

member of his church choir. 

It is Backman’s dedication to his industry, 

community and exceptional dedication 

to training new agronomists 

that led to his nomination as CCA of 

the Year, Pier said. 

“I was honored by the selection,” Backman 

said. “I appreciate the recognition; 

it’s nice to know what you have done 

for the past 45 years is valued and to be 

able to see the changes in the industry 

from some of the things I’ve introduced.” 

Among the changes he has seen in 

recent decades: more accurate nitrogen 

and water applications; more accurate 

monitoring to take appropriate actions 

at the appropriate times; and the 

application of science in making those 

applications using plant science and 

physiology to guide those decisions. 

This is the second year Western Region 

CCA presented an annual Crop Consultant 

of the Year award to recognize 

outstanding individuals who have 

advanced crop consulting throughout 

their careers. For information on 

nominating a CCA visit the Western 

Region CCA website at https://wrcca. 

org/cca-of-the-year. 





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Leaf Sap Analysis: A 

Forward-Looking Alternative 

to Tissue Sampling 

By SEAN JACOBS | Technical Sales and Marketing Representative, Agro-K Corp., Contributing Writer 

Leaf sampling in agricultural crops is a 

long-practiced sampling method where 

the analysis of the collected tissues is used 

to assess crop nutrient status. Sampling whole 

leaves, drying, grinding, digesting and then 

analyzing the sample for nutrient levels has 

aided farmers in managing their crop nutrition 

programs and optimizing crop yield. 

This method, however, has some inherent 

limitations. Primarily, the results of the 

analysis are providing nutrient levels for ALL 

nutrients in the sample, including those that 

are structurally bound within cell walls, the 

leaf surfaces (cuticles) and organelles. While 

the analysis is accurate in quantifying the 

nutrient levels in the sample, these bound nutrients 

are largely immobile and unavailable 

to developing leaves and fruit. 

Both over-applications and mistimed applications of nutrients 

can negatively affect crop yields and quality. 

Additionally, any nutrients found on the outside 

of the leaf or embedded in the leaf cuticle 

are included in the results. As an example, if 

a calcium carbonate material were applied foliarly 

to a crop and then tissue samples were 

pulled, the analysis would demonstrate that 

our tissue’s calcium levels increased. On the 

other hand, calcium carbonate materials have 

very poor foliar uptake and are commonly 

used as solar protectants or sunscreens. As 

a sunscreen, it is necessary that the material 

remains on the leaf surface to do its job, but a 

standard tissue sample analysis cannot differentiate 

between “in” or “on” the leaf. Further, 

tissues being prepped for analysis may be 

rinsed or washed in an attempt to alleviate 

leaf surface contaminants. What is commonly 

overlooked with this practice is the effect 

that rinsing can have on nutrients within the 

leaf. For instance, potassium, calcium, magnesium, 

manganese, nitrogen, phosphorus 

and zinc can all be leached to varying degrees 

from the leaf tissue with water. 


Now, if the grower is analyzing the leaf 

tissue because it is the crop, then knowing 

the nutrient levels of the entire leaf 

structure and surface is appropriate. 

However, many growers are not selling 

leaves but are using the leaves as the 

machinery to develop the structure 

of the plant and produce the end crop. 

Whether that end crop is a tuber, fruit, 

nut, seed or simply a flower, knowing 

the number and quantity of nutrients 

available for assimilation within the 

plant as well as the balance among 

these nutrients may spell the difference 

between a mediocre crop and a stellar 

crop. Knowing and adjusting the 

nutrient balance is crucial to nutrient 

performance and preventing fruit nutrient 

disorders which can impact crop 

storability and shelf life. Other characteristics 

such as fruit sugar levels, size 

and color also can be positively impacted 

by proper nutrition. 

Forward Looking Analysis 

An alternative method to leaf tissue 

analysis is sap analysis. With sap 

analysis, leaves are sampled in sets 

with new leaves and old leaves collected 

separately without petioles. At the 

lab, a proprietary process under the 

NovaCrop brand then extracts the sap 

from the leaf. This process is done without 

rinsing, drying, grinding, cutting 

or crushing the leaves and the extracted 

sap is largely free from leaf structural 

components and surface contaminants. 

This results in the extracted sap being 

more similar to a blood sample than 

the biopsy approach akin to classical 

tissue sampling and analysis. In 

addition to analyzing the samples for 

19 nutrients and five other nutrient and 

metabolic indicators, having the sap 

of both new and old leaves analyzed 

separately allows for the comparison of 

nutrient uptake, mobility and remobilization 

within the plant. This comparison 

is also valuable for assessing the 

movement of sugar in the plant, which 

is the plant’s initial building block and 

energy source. 


By quantifying the metabolically active and available nutrients in the sap and 

assessing their balance, growers are able to determine not just if nutrient 

deficiencies exist but also the future potential for nutrient deficiencies (photo 

by Cecilia Parsons.) 

Fruit Growers Laboratory, Inc. 

Precision Analyses for Improved Crop Quality & Yield 

www.fglinc.com 

SOIL 

FOOD 

SAFETY 

DISEASE 

I.D. 

LEAF 

TISSUE 

PARASITIC 

NEMATODE 

WATER 

ORGANIC 

AMENDMENTS 

Contact One of Our Convenient Locations for Assistance 

Corporate Offices & Lab 

Santa Paula, CA 

(805) 392-2000 

Office & Lab 

Stockton, CA 

(209) 942-0182 

Office & Lab 

Chico, CA 

(530) 343-5818 

Office & Lab 

San Luis Obispo, CA 

(805) 783-2940 

Office & Lab 

Visalia, CA 

(559) 734-9473 



Minerals, sugars and nitrogen-containing 

compounds, such as amino 

acids and proteins, found in the sap 

represent the majority of plant nutrients 

that are immediately available 

for use. By intentionally sampling and 

analyzing leaf sap, the results provide 

a forward-looking picture of the 

nutritional environment in which the 

plant is currently growing. With this 

information, deficiencies, toxicities 

and nutritional imbalances can be 

identified and corrected in a proactive 

manner, often before their physiological 

effects are visible. With traditional 

tissue analysis, the results are providing 

information largely about what has 

already happened nutritionally, leading 

to decisions being reactive in nature. 

As the demand for agricultural products 

continues to increase, farmers are 

often turning to more aggressive fertility 

programs, which frequently leads to 

over-applying nutrients or missing the 

best opportunity for the application. 

Both over-applications and mistimed 

applications of nutrients can negatively 

affect crop yields and quality. The 

balance of nutrients within the plant 

can be upset by an over-applied nutrient. 

This can happen with foliar-applied 

nutrients as well as soil-applied 

nutrients. In some instances, as with 

nitrogen, it can alter the expression/ 

regulation of genes and lead to a shift 

in growth toward vegetative and away 

from fruit development. In other cases, 

the over-applied nutrient can create 

nutrient imbalances that present as 

deficiency symptoms of other nutrients 

despite adequate concentration levels in 

the sap. This can be described as likekind 

interactions where minerals of 

similar charge are competing with each 

other for space within the sap (cations 

affect cations and anions affect anions.) 

Physiological responses within the 

plant to an applied nutrient can modify 

the uptake or physiological activity 

associated with other nutrients, either 

positively or negatively. 

Nutrient Availability 

By removing unavailable nutrients 

from the analytical picture, the concentrations 

of available nutrients and 

their interactions are more easily seen 

in the analysis and accommodated for 

in the grower’s nutrition program. In 

the soil, colloidal and mineral properties 

influence how various nutrients, 

specifically cations, populate the 

cation exchange locations. A key takeaway 

is that these soil interactions occur 

primarily with available nutrients. 

The same is true within the plant with 

nutrient interactions primarily between 

available nutrients not unavailable 

and structurally bound nutrients. 

This is where sap analysis shines. 

By quantifying the metabolically 

active and available nutrients in 

the sap and assessing their balance, 

growers are able to determine not 

just if nutrient deficiencies exist but 

also the future potential for nutrient 

deficiencies. With a NovaCrop sap 

analysis in hand, growers are able to 

evaluate the balance of nutrients in 

their crop and better understand how 

excessive levels of nutrients may impact 

the uptake and/or activity of others. 

Through this analytical report, a 

grower might determine that the most 

efficient way to increase the level of a 

certain nutrient is NOT by applying 

more of that nutrient, but rather is best 

achieved by decreasing the rate of other 

applied nutrients and restoring balance. 

Over-application of nutrients affect the 

safety of ground and surface water for 

human consumption and the wildlife 

dependent on those water sources. In 

an ever-increasingly regulated world, 

leaching and runoff of nutrients caused 

by over-application are not merely 

wasted money and crop potential, but 

could result in the grower being fined 

thousands of dollars, reclamation fees 

and civil judgements. Fertility management 

plan modifications, when based 

on NovaCrop sap analysis, and coupled 

with soil analysis, improves fertilizer 

use efficiencies and decreases over 

application of nutrients. 





Maximizing Nut Set & 

Size Under Dry Conditions 

The Record-breaking drought and heat seen across California in 

2021 is forecasted to continue into 2022. With drier springs comes 

reduced disease pressure to almond blooms and nutlets. This often 

means that fungicide applications at pink bud and bloom can be 

decreased or eliminated. While it can be tempting to leave the sprayer 

in the barn, almond growers’ nut set, size and yield depend on earlyseason 

foliar nutrition. 

Growers that want to achieve maximum economic yield, however, 

would be wise to reallocate their fungicide dollars to where they can 

get the best return. The value of a good nutritional program cannot 

be overstated. In fact, well designed nutrient programs are even more 

essential in a dry year. Without moisture from rain, pollen and flowers 

desiccate rapidly. Desiccation reduces pollen’s viability shortening the 

bloom receptivity window which reduces nut set and yield. Starving 

the developing flowers and nutlets of essential nutrients intensifies 

the reduction. 

The right nutrients applied during the pink bud and bloom window 

can make all the difference. Vigor-Cal-Bor-Moly, a sugar complexed 

calcium foliar combined with boron and molybdenum, is an excellent 

fit for pink bud and bloom time sprays to improve nut set and quality. 

With a shorter bloom window, supplemental boron ensures successful 

germination and pollen tube development—also known as nut set. 

Molybdenum, a key component of nitrogen metabolizing enzymes 

and others, facilitates stress responses, vascular development, and 

growth. Symspray, Agro-K’s seaweed product, when applied during 

pink bud and bloom can reduce the effects of environmental stress on 

the flowers, extending bloom and increasing pollen receptivity even 

when it is dry. 

By adding AgroBest 9-24-3 to the tank with Vigor-Cal-Bor-Moly 

during cell division, calcium and phosphate work together to promote 

larger and heavier nuts. AgroBest 9-24-3 is a high phosphate/low 

potassium blend that delivers the phosphate energy the tree needs 

to maximize nut cell division, nut size and nut retention. AgroBest 

9-24-3 is the most cost-effective liquid phosphate available. It 

delivers more phosphate per dollar at peak demand timing and 

is specifically designed with minimal potassium content for early 

season foliar applications that won’t waste dollars or antagonize 

calcium during nut and leaf cell division. 

Ultimately, almond growers that leave their sprayers in the barn 

will produce smaller, lighter nuts and lower yields. Reducing the 

number of dry-season fungicide sprays leaves more money in the 

budget for a science-driven foliar nutrition program. Reallocating 

some of these funds for applications that drive higher yields and 

increase nut size is a smart way to ensure the biggest benefits from 

less-than-ideal environmental conditions. After all, growers still 

need to maximize their economic yield, as their costs and expenses 

continue to go up, not down. 

While foliar nutrition is essential during the pink bud and bloom 

window to maximize economic yield, it is very important throughout 

the season. A dry year requires almond growers to think critically 

about the key nutrients they apply at each growth stage to produce 

more nuts with less water. Implementing a Science-Driven 

nutrient approach this year will deliver more pounds of nuts per unit 

of water resulting in higher economic returns per acre for you. 

Products Available At: 

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Soil Microbes are Key Partners 

for Drought Management 

By DR. KARL WYANT | Vice President of Ag Science, Heliae® Agriculture; Chair, 

Western Region CCA Board of Directors 

Management practices that 

improve soil health and soil 

quality have gained considerable 

attention over the past few years, 

and especially during the past year, as 

drought conditions have impacted large 

areas of North America. In this article, I 

focus on how the living, biological components 

of the soil (e.g., bacteria and 

fungi) can be key microbial partners 

in your future drought management 

strategy. 

Soil Health and Drought Management 

Figure 1. Here are two concepts to help organize the contribution of microbes to soil health 

and structure (Concept 1) and the substances that are released by the microbes themselves 

(Concept 2) that help crops get through a drought period (courtesy K. Wyant.) 

I detail how soil microbes impact soil 

physical properties, including the 

structure (e.g., aggregation and pore 

space) and the ability of the soil to 

move and store water. Additionally, I 

explain how soil microbes can help 

crops get through drought conditions 

using the substances they secrete. 

Finally, I close with a call to action 

to measure your soil biology so you 

can make management decisions now 

before the next season gets underway. 

If needed, a CCA can help you interpret 

data and make an actionable plan that 

can help tackle the continued drought 

conditions that are expected for the 

near future. 

Let us begin with a quick reminder 

of what soil health means to a grower 

and how it is connected to the 

living component underground and 

drought management. Soil health is 

directly related to the interaction, or 

lack thereof, between organisms and 

their environment in a soil ecosystem 

and the properties provided by such 

interactions. When you think of soil 

health, think of the biological integrity 

of your field (e.g., microbial population 

and diversity) and how the soil biology 

supports plant growth. There is a direct 

link between soil health and how a soil 

can be managed to meet the challenges 

of drought conditions. 

Soil Microbes and Drought 

Management 

Soil microbes impact your ability to 

manage drought via two major pathways, 

i.e., the “Two Concepts of Drought 

Management” (Figure 1). 

Concept 1: Soil Microbes Help Increase 

Water Penetration and Infiltration 

Soil microbes help restore soil structure 

which helps water move from the 

soil surface downwards. This is known 

as water penetration. Once the water 

has penetrated the soil, it moves down 

into the soil for storage. This is known 

as water infiltration. If you are not 

capturing and moving water into the 

soil, you will have a tough time storing 

water in your field. Simply put, healthy 

soils have good structure, which excel 

at receiving and storing moisture. But 

how exactly do microbes improve water 

penetration and infiltration? 

Abundant and diverse soil microbial 

communities produce “free” services 

for your farm soil, including the ability 

to receive and store moisture. The 

key to this ability lies in the ability of 

microbes to contribute directly to improving 

soil structure by binding soil 

particles together, which, in turn, helps 

water move from the soil surface and 

into the root zone. 

Soil bacteria produce a sticky, gluelike 

gel called extracellular polymeric 

substances (EPS) that form a protective 

slime layer around bacteria as they 

grow. The EPS acts as an adhesive to 

bind soil particles, thereby improving 


A Living Soil Helps with Drought Management 

Figure 2. The soil on the left has poor soil health and soil structure while the soil on the right has excellent soil health and, as a result, 

the two fields have substantial differences in soil quality and their ability to mitigate drought stress (courtesy K. Wyant.) 

overall soil structure. Fungi, another important group of soil 

microbes, produce miles of microscopic threads in the soil 

called hyphae. The threads capture and “tie” soil particles 

together, like a net, which improves overall soil structure. 

Fungi also produce a sticky protein-like substance called 

glomalin which, like EPS, helps bind your soil structure 

together via adhesion of particles. 

Key Message: Soils with healthy microbial populations can 

restructure and re-aggregate the soil, which leads to better 

soil structure overall. Good soil structure allows for water 

(e.g., snowmelt, rainfall and irrigation water) to move from 

the soil surface (penetration) to below the soil surface for 

storage around and on the soil particles themselves (infiltration). 

This results in a number of benefits, including reduced 

runoff losses. 

Research and grower experience corroborate this connection 

as reports show that soils with good structure often can store 

more water relative to degraded control fields nearby. Good 

soil structure also reduces runoff losses as water quickly 

moves downwards instead of horizontally across the soil surface, 

which carries materials off the field. Thus, soil microbes 

can be crucial partners for capturing and storing soil moisture, 

which will certainly come in handy during forecasted 

drought periods. 

This next concept is not so easy to visualize like changes in 

soil structure and the ability to store water. Imagine the microbial 

community on the right side of Figure 2 for the next 

few sentences and contrast the microbial abundance and diversity 

when compared to the “business-as-usual” farm soil 

on the left side. Now that you have refreshed your snapshot 

Advertorial 

Oregon State has developed an Aglime Score 

which is basically an efficiency rating. Particle size or 

mesh size is key to this rating and is the primary 

indicator of reactivity. Studies have shown that pulverized 

limestone smaller than 40 mesh (size of table 

salt) are considered 100% effective and are the 

quickest to dissolve in the soil to release calcium and 

adjust soil pH. 

Mildly acidic water and soil conditions will dissolve 

finely ground limestone. For example, the pH of 

rainwater in California is typically around 5.7, which is 

enough to dissolve our aglime that is broadcast. Our 

pulverized limestone products average 85% passing 

100 mesh (diameter of a human hair). Remember 

aglime quality increases when particle size decreases. 

U.S. 20 Mesh 


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Concept 2: Robust Microbial Communities Release Substances 

to the Soil Which Can Help Crops Get Through Periods of 

Drought 

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Blue Mountain Minerals 

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of the microbial community, we can 

turn our attention to the benefits that 

improved microbial abundance and 

diversity bring to a drought affected 

soil. Recent work has shown that soil 

microbes help crops get through periods 

of drought stress via the substances 

they release into the soil around the 

roots. These molecules include osmoprotectants 

and antioxidants, to 

name just a few (see first reference for a 

deeper dive). 

Key Message: A hidden benefit of 

maintaining a thriving community 

of microbes during a drought are the 

substances they secrete. For example, 

osmoprotectants play a key role in 

managing challenges with plant water 

balance under drought conditions. In 

another example, antioxidants help 

mitigate oxidative stress and internal 

plant cell damage observed under 

drought stress. Studies show that when 

a robust microbial community releases 

certain substances belowground, a 

crop is better able to weather the stress 

of drought (e.g., low rainfall, higher 

temperatures) more successfully aboveground. 

Managing Soil Biology 

Now that we have examined how soil 

microbes can be crucial partners under 

drought conditions, we can now turn 

our attention to a crucial next step: 

managing the soil biology. I will walk 

through the basics on how to measure 

the biological activity of the soil and 

make the case to ask your trusted 

CCA for assistance if this management 

strategy is new to your operation or if 

you need help with interpretation of the 

results. 

Tests are commonly used to measure 

chemical constituents of the soil (e.g., 

pH, nitrate, phosphate, etc.) or physical 

aspects of the soil (e.g., soil texture, 

cation exchange capacity). However, 

these tests do not determine how 

“alive” the soil is. You can accomplish 

this goal with a broad set of soil tests 

that target the living components 

of soil. Soil biology tests are diverse 

and include measurements of carbon 

Test Name 

CO2 Burst 

Test 

ACE Protein 

Test 

Active 

Carbon Test 

Water Holding 

Capacity Test 

Aggregation 

Test 

What It Measures 

Table 1. There are several soil tests available to help you quantify the living components 

of your soil and their response to field management decisions. Please see the 

“Comprehensive Assessment of Soil Health” from Cornell University for an exhaustive list 

on what is available or call your local lab. Listed are a few common testing options in ag 

laboratories. 

dioxide respiration, extraction of DNA 

for microbial community analysis, and 

other key metrics (Table 1), depending 

on what parameter you are interested 

in measuring and your patience level to 

see a measurable change. 

Testing the biological components of 

the soil is new to many growers and 

some have reported frustration about 

which test to choose, how to design a 

sampling program, and how to interpret 

and write an actionable plan 

based on the test results. This is where a 

Certified Crop Advisor can step in and 

help reduce the learning curve. 

Final Thoughts 

Soil microbes can help you mange 

drought in ways that are readily observable 

(e.g., changes in soil structure 

and water holding capacity) and in 

ways that are not (e.g., release of substances 

that help with drought stress). 

In any event, microbes are essential 

partners for dealing with drought 

conditions and their usefulness should 

be leveraged in any crop production 

program. 

Dr. Karl Wyant currently serves as the 

Measures the activity of the oxygen-using soil 

microbes (fungi + bacteria) as they “breathe out” 

CO2 during their daily activities. Higher CO2 

measurements indicate more microbial activity at 

the time of sampling. 

Measures how much “protein-like” substances are 

in a field. Higher ACE protein values indicate 

more organically bound nitrogen that microbes 

can release for future plant uptake. 

Measures the amount of materials available to 

“feed” soil microbes. Higher active carbon test 

values indicate that there is more food available 

to fuel microbial work. 

Measures how much moisture your soil can 

hold, which is influenced by soil biology and 

structure. Higher values indicate better water 

storage on a field. 

Measures the physical structure of your soil, which 

is strongly influenced by soil biology. Larger 

particle sizes typically indicate better soil 

structure. 

Vice President of Ag Science at Heliae ® 

Agriculture. To learn more about the 

future of soil health, you can follow his 

webinar and blog series at www.phycoterra.com. 

Suggested Reading 

Speed of 

Response 

Changes 

daily 

Changes 

weekly or 

monthly 

Changes 

weekly or 

monthly 

Changes 

slowly over 

growing 

season 

Changes 

slowly over 

growing 

season 

Harnessing rhizosphere microbiomes 

for drought-resilient crop production 

- https://www.science.org/doi/10.1126/ 

science.aaz5192 

The Connection Between Your Soil 

Structure and Soil Moisture - https:// 

phycoterra.com/connection-betweensoil-structure-soil-moisture-crop/ 

Biological Management Practices 

to Maximize Soil Quality - https:// 

progressivecrop.com/2021/05/managing-soil-structure-and-quality/ 

Comprehensive Assessment of Soil 

Health (The Cornell Framework) - 

https://soilhealth.cals.cornell.edu/training-manual/ 





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© 2021 AgroLiquid. All Rights Reserved. 


Use of Gypsum to Reclaim Salt 

Problems in Soils 

Three-year viticulture case study illustrates response 

of gypsum application to soil, grapevines and fruit. 

By LUCA BRILLANTE |Bronco Wine Co. Chair & Assistant Professor of Viticulture, Department of Viticulture & Enology, 

California State University, Fresno 

and KHUSHWINDER SINGH | Graduate Research Assistant, Department of Viticulture & Enology, Fresno State University 

Figure 1. Effect of severe salt stress on young and mature grapevines (all photos courtesy L. Brillante.) 

Soil salinization is caused by excessive 

accumulation of salts in the 

soil and is one of the most severe 

land degradation problems. Globally, 

salt-affected soils are estimated to be 

about 2 billion acres and are expected 

to increase in the future. In California, 

about 4.5 million acres of irrigated 

cropland (more than half) are affected 

by salinity, causing significant problems 

to the state’s agriculture. When salinity 

levels exceed critical thresholds in the 

soil, the plants cannot reach their full 

genetic growth potential, development 

and reproduction. 

Causes and Consequences 

of Soil Salinity 

Soil salinity can be related to the origin 

of the soil (e.g., in soils from land that 

was once submerged under the level of 

the sea or a lake.) It can also be caused 

by humans. Irrigation in dry areas exacerbates 

the problem as water contains 

salts that are left in place after evapotranspiration, 

and there is not enough 

rainfall to help with the leaching (i.e., 

the process of washing off excess salts 

from the surface toward the deeper 

layer of the soils and out of the reach of 

plants.) 

Salinity can be caused by excess in different 

kinds of salts, including table salt 

(NaCl), potassium chloride (KCl), etc. 

Table salt is the most common and most 

problematic. It is composed of sodium 

ions (Na + ), which negatively impact 

soil physical-chemical properties and 

create an osmotic stress in plants, and 

chloride anions (Cl - ), which are toxic to 

plants. 


Accumulation of sodium in soils causes swelling of clays, 

destroys soil structure and reduces infiltration and water 

holding capacity (Figure 2). This reduces the oxygen & 

water availability to roots. Excess of salts in the soil generates 

osmotic stress, which affects grapevine physiology 

and performance. At low rates, it is a chronic problem that 

disturbs grapevine water relations, causes stomatal closure 

in grapevine and reduces leaf and crop size. At high rates, it 

can create toxicity problems that can lead to premature leaf 

senescence and plant death (Figure 1, see page 22). 

Salt buildup can result in three types of soils: saline, saline-sodic 

and sodic. Salinity & sodicity terms are used 

interchangeably very often. However, salinity refers to the 

concentration of salts (of all kinds) in the soil. Sodicity is 

associated with the proportion of sodium in pore water or 

adsorbed to the mineral surface. In saline soils, there are 

enough soluble salts of all kinds to injure plants. Sodic soils 

are low in soluble salts but relatively high in exchangeable 

sodium. Saline-sodic soils have a high content of salts and 

high content of sodium relative to calcium and magnesium 

salts. 

The electrical conductivity of soil extracts can measure soil 

salinity, as with more salts in the water, it is easier for the 


Figure 2. Effect of salt stress on the soil, showing reduced 

infiltration, surface crust formation, and clays’ dispersion. 

Contact us to see how we can help! 

(559)584-7695 or visit us as www.superiorsoil.com 

Serving California since 1983 



current to flow. Sodicity of soil is indicated by the exchangeable 

sodium percentage (ESP), which is the soil cation 

exchange capacity occupied by sodium, or by the measure of 

sodium adsorption ratio (SAR), which represents the amount 

of sodium with respect to calcium and magnesium. Saline, 

sodic and saline-sodic soils can be differentiated according 

to their physical-chemical properties. Soils with EC > 4 dS/m, 

SAR 4 dS/m, SAR >13, pH

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Calcium plays a key role in 

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Pacific Gro should be viewed as a core input and key 

contributor to any crop program. It helps microbes get 

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Fish oil and chitin provide the necessary building blocks for 

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Figure 3. Gypsum application in our study. 


ant when water for irrigation is alkaline. If 

gypsum is not applied regularly and calcium 

content decreases in the soil, the soil tends 

again to get compacted and the infiltration of 

water slows down, creating stress to plants. 

Figure 4. Infiltration rate measured by the single ring infiltrometer method 

in the year after the application. See the text for treatments corresponding 

to code. 

Figure 5. Amount of calcium in the soil solution in the year after the treatment 

application. The soil samples were extracted with the ammonium acetate 

method and measured with MP-AES. See the text for treatments corresponding 

to code. 

It is recommended to spread gypsum on 

soils as an application through low-volume 

irrigation sources (i.e., drip and sprinklers) 

and is shown to work best with irrigation 

water of low salinity, i.e., about 0.1 ds/cm. 

Liquid gypsum application can increase the 

water infiltration to greater depths under the 

emitters over time due to soil particle binding 

and aggregation properties of calcium. When 

gypsum is applied through drip lines with irrigation 

waters of high bicarbonate content, it 

requires cautionary measures and lowering of 

pH (

’ 

Of particular importance 

under dry conditions 

is the ability of plants 

to access and use the 

water in the crystalline 

structure of gypsum. 

Figure 6. Yield per vine (1kg = 2.2 pounds) in the year of treatment 

application (2020) and in the year after application (2021). 

randomized block design with six treatments replicated four 

times, and each replicate was 0.2 acres large. 

The treatments were applications of gypsum at different rates: 

2.5 t/ac (50% reclamation rate, code 50G), 5.1 t/ac (100% 

reclamation rate, code 100G), 10.2 t/ac (200% reclamation 

rate code 200G), application of anhydrite at 5.1 t/ac (100% 

reclamation rate, code 100A) and addition of compost to 

gypsum (5.1 t/ac gypsum + 1t/ac compost (code 100GC)). We 

included one untreated control (code CTRL). All treatments 

were applied in one single application at the beginning of the 

experiment. 

Calcium amounts in the soil extracts (obtained after treatment 

of soil samples with ammonium acetate) increased 

in all treatments with respect to the control one year after 

the application, both in the top eight inches and at a depth 

between 8 and 16 inches. We observed the largest increase in 

the 100G, which had 28% more exchangeable calcium ions on 

the soil particles than the control in the top eight inches and 

15% more in the 8- to 16-inch depth (Figure 4, see page 26). 

Sixteen months after the application, we started observing 

effects on water infiltration rate in the soil, with the untreated 

control showing the lowest water infiltration rate. The 200G 

and 100GC showed the highest infiltration rate with 65% and 

63% improvement over the control, respectively (Figure 5, 

see page 26). 

as the following year (5%). The other treatments did not have 

positive effects on yield. We did not observe significant differences 

in sugar content (Brix), pH or titratable acidity of musts 

across treatments. 

This trial showed that gypsum effectively reduces the adverse 

effects of salt stress on soils and vines by increasing calcium 

ions at the surface of clays. The increase of calcium ions improves 

soil structure with positive returns on infiltration rates 

and the increase in soil health promotes grapevine performance 

and increases yield. The addition of compost enhances 

the positive effects of gypsum. 

References 

Palacio et al., 2014 The crystallization water of gypsum rocks is 

a relevant water source for plants. Nature Communications 5, 

4660. 

Comments about this article? We want to hear from you. Feel 

free to email us at article@jcsmarketinginc.com 

We did not observe notable differences in plant water status 

measured by a pressure chamber (water potentials), neither 

in photosynthesis nor transpiration across the treatments. In 

the two years after the treatment, we observed higher yields 

in the 200G and 100GC with respect to all other treatments 

and the control (Figure 6). The response was more robust in 

the year of the application, in particular for the 100GC, with 

plants producing 15% higher yield than the control, but only 

2% more than the control in the second year. At the same 

time, the effect of the 200G was more consistent and was 

higher (8%) with respect to the control the same year as well 


Diagnosing Vineyard Problems 

Data Collection and Understanding 

Patterns to Mitigate Damage and 

Yield Loss 

By STEPHEN VASQUEZ | Technical Viticulturist, Sun-Maid Growers 

The 2021 season was a challenging 

year for western grape growers. 

After an unusually dry, cool winter, 

many growers observed poor shoot 

growth and various fruit maladies from 

bud-break through harvest. Delayed 

spring growth, vine mealybug and leaf 

hopper infestations, heat waves and 

water shortages were just a few of the 

issues that caused problems for grape 

growers. 

Farmers and viticulturists were busy 

trying to diagnose various vineyard 

problems from shortly after bud-break 

through leaf fall. Diagnosing vineyard 

problems as soon as possible is important 

for minimizing yield and quality 

losses, especially when caused by pests 

that can be managed before moving 

into neighboring vineyards. However, 

when a quick diagnosis cannot be made, 

it is important to survey the vineyard 

and collect as much information as 

possible so damage can be mitigated. 

Prompt Data Collection 

When trying to diagnose abnormal 

plant growth, it is important to collect 

as much data as possible near the time 

that it was first observed. Data in the 

form of dates, symptoms (e.g., abnormal 

growth), signs (e.g., insects), records, 

etc. are important for you and those 

you may consult with in determining 

the cause of poor growth. Table 1 highlights 

important information to collect 

for proper diagnosis. The most basic 

information focused on vineyard characteristics, 

such as variety/rootstock 

combination, weather, soil, irrigation 

type, grape tissue analysis, etc., are 

typical data needed to solve vineyard 

problems. Sometimes, it can take days 

or weeks of consideration to determine 

what has affected the vines. However, 

there are times when a problem remains 

unsolved, even after data have been collected 

and reviewed by multiple experts. 

After basic vineyard characteristics, re- 

Table 1. Data collected to help iden2fy vineyard problems 

ports (see Table 1) of varying types are 

important pieces of information for deciphering 

vineyard issues. Phenological 

dates, yield and quality, fertilizer and 

pesticides used, etc. give clues about 

what has happened this season and in 

past years that may correlate with a 

particular issue. The more reports that 

are available for review, the easier it will 

make solving the problem. 

Photos are a great tool because they can 

easily and quickly be shared via email 

or text. Today’s phones are equipped 

with a camera that can capture both 

photos and video that make documenting 

vineyard problems easier. However, 

there is a difference between a photo 

and a great photo that can help solve 

the cause of symptoms. Great photos 

show detail that can aid in determining 

the cause of symptoms. For example, 

a picture of a single leaf on the bed of 

a truck probably won’t help identify a 

problem. A more useful photo would 

VINEYARD 

CHARACTERISTICS 

REPORTS 

PHOTOS 

LABORATORY 

ANALYSIS 

- Variety 

- Rootstock 

- Vineyard age 

- Soil type 

- Irrigation type 

- Surrounding vegetation (crops and 

native) 

- Yield and quality 

- Pesticide use 

- Fertilizer use 

- Soil maps 

- Soil and water amendments 

- Establishment 

- Production practices 

- Previous crops grown 

- Source of plant material 

- Leaves 

- Canopy 

- Fruit 

- Roots 

- Cross section of canes, cordons, 

trunk 

- Pests 

- Surroundings 

- Aerial images 

- Water 

- Soil 

- Tissue 

- Leaves 

- Stems 

- Roots 

- Insects 

- Diseases 

Table 1. Data collected to help identify vineyard problems 

28 Table Progressive 2. Some likely Crop Consultant causes and January symptoms* / February of certain 2022 pa>erns found in vineyards.

highlight multiple symptomatic leaves showing their location 

on the grapevine and in the vineyard, which may highlight 

the root cause of a problem. 

Water, soil and tissue laboratory analysis when taken annually 

help identify trends over seasons. The best approach is to 

pull samples at specific times (i.e., growth stages) each year so 

the information is available when decisions need to be made. 

For example, taking water samples at the beginning of the 

growing season will help determine how much nitrogen is 

coming from irrigation water sources. Once known, planned 

fertilization rates can be adjusted depending on the amounts 

in the water. Excess nitrogen applied during the season without 

knowing what is in well water can contribute to poor fruit 

quality and may further contaminate the aquifer. 

Biotic vs Abiotic 

Vineyard issues affecting vine health and fruit production fall 

into two categories: biotic or abiotic. Issues caused by insects, 

fungi, bacteria, viruses, rodents, birds and other living 

organisms are biotic. Abiotic includes non-living factors like 

climate, soil compaction, water, pH, nutrient presence or lack 

thereof, etc. Biotic factors tend to be the most common reason 

for poor grapevine health but aren’t always the primary cause. 

Trying to separate symptoms between biotic and abiotic vine 

health issues can take time to sort through since symptoms 

can have multiple causes. For example, a vineyard may be 

showing signs of decline due to root rot infections. However, 

the real cause may be the presence of hardpan not allowing 

water to drain. Water accumulating around vine trunks often 

leads to fungal infection, decline and vine death. Symptoms 

from both fungal infections and poor water penetration can 

have similar symptoms (weak vine growth with chlorotic foliage). 

Identifying the primary cause is important so a solution 

can be developed and implemented. 

M 

Understanding Patterns 

Y 

Patterns of symptomatic vines are an important piece of information 

needed to solve the cause of poor vineyard growth. CM 

An easy way to identify patterns is the use of aerial imagery 

MY 

(Figure 1) to survey your vineyard. Aerial imagery has improved 

tremendously and can help detect differences in vine 

CY 

CMY 

growth, soil and irrigation issues, pest or disease problems 

and more. Accessing aerial imagery is as easy as using your K 

own drone to capture footage or hiring a licensed pilot or 

company to take photos and video for you. 

Data from aerial imagery can also be transformed into 

helpful indices such as NDVI, and specialized sensors such 

as thermal or hyperspectral images provide additional data 

for assessing vineyard condition. Aerial imagery can help you 

track irrigation problems or general vine health throughout 

the season by outlining patterns based on vine growth and 

leaf condition. 

C 

Driving and walking vine rows with a soil map in-hand can 

be essential for assessing problem areas. Surveying the vine- 


Figure 1. Aerial vineyard view taken in 1985 showing sand 

streaks that produce weaker vines that often produce lower 

yields than the other parts of the vineyard. Aerial imagery 

taken today can be taken with specialized sensors that provide 

additional data for assessing a vineyards condition (photo by L. 

Peter Christensen.) 

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yard on foot or with an ATV allows for 

a closer look at low-vigor areas, which 

may give you management clues that 

can complement aerial imagery. Patterns 

of poor growth found on vineyard 

edges, down rows or in small patches 

are sometimes easily solved when those 

areas are visited on foot. For example, 

Figure 2 shows multiple vines within 

a row that are weak or dead. At first 

glance, a disease might be suggested 

as the cause of poor growth and death. 

But after further investigation from 

top to bottom, it was found that the 

base of the vine and root system had 

been chewed and girdled by meadow 

voles. Once the problem was identified, 

a management plan was implemented, 

which ended additional vine deaths. 

Symptom Diagnosis 

Diagnosing abnormal growth symptoms 

is somewhat of an art and a science. 

When called to identify the cause 

of poor or unusual growth, a vineyard 

diagnostician must consider all the scenarios 

that might be causing symptoms. 

A methodical approach that results 

in an accurate diagnosis is important 

since time is of the essence when 

considering management strategies 

to minimize yield and quality losses. 

Variety, rootstock, vineyard age, soil 

type(s) and depths, irrigation methods 

and timings, nutrition, common pests, 

diseases, climate and many other factors 

must be considered. A systematic 

approach must be taken to identify the 

primary cause that includes symptoms 

found in the vineyard, including related 

reports, photos and laboratory analyses. 

Diagnosing grape pests or diseases can 

be easier than abiotic causes since three 

factors need to be present: the pest or 

disease, grape (i.e., host) and favorable 

environmental conditions. 

Table 2. Some likely causes and symptoms* of certain pa>erns found in vineyards. 

VINEYARD 

PATTERN 

Down the vine row 

Irregular, related to soil type 

Irregular, related to abiotic 

causes 

Seasonal impacts 

Irrigation 

Gopher damage 

Mechanical injury 

LIKELY CAUSES* 

Nutrient deficiencies 

Salinity or alkali 

Soil compaction 

Moisture: deficiencies or excess 

Rootstock differences 

Nematodes or phylloxera 

Plant diseases 

Inadequate irrigation 

Leveled ground; topsoil moved 

Chemical drift 

Mechanical injury; i.e. tractor blight 

Girdling; i.e. grafting tape 

Temperature related 

Frost or freeze events 

Cool weather post budbreak 

Hot weather 

*Specific pest, disease and nutrient deficiency symptoms have not been included in this table. 

as causes, a diagnostician must spend 

time reviewing reports, lab analysis 

and walking the vineyard looking for 

patterns and additional clues. A shovel, 

shears, soil probe, and a lot of time will 

be needed to narrow down the cause. 

LIKELY SYMPTOMS 

Poor growth, yellowing leaves 

Weak or dead vines 

Weak or dead vines, poor growth, leaf color 

Various leaf colors and foliar patterns 

Marginal leaf burn, chlorosis 

Weak vine growth, chlorosis 

Chlorosis 

Varying vine growth & foliar patterns 

Weak vine growth, chlorosis 

Weak vine growth, varying foliar patterns 

Poor growth, chlorosis or reddening 

Weak vines, poor canopy growth 

Spotting on leaves and fruit, dead vines 

Weak or dead vines, poor growth, color 

Weak, poor growth, dead vine 

Dead leaves, shoots, or vines 

Spring fever symptoms 

Burnt leaves, dead vines 

Table 2. Some likely causes and symptoms* of certain patterns found in vineyards. 

Figure 2. Multiple vines in a row displaying discolored foliage that 

looks to represent a virus infection. However, a closer look (photo 

inset) reveals that the base of the trunk and larger structural roots 

have been chewed on by meadow voles. As a result of the chewing, 

the vines were girdled and displayed reddening symptoms, which 

is similar to a virus infection (photo courtesy S. Vasquez.) 

Finding a trusted advisor can also be 

daunting because there’s often a cost 

associated with hiring someone. Here 

are some considerations for finding and 

hiring a CCA, PCA, private consultant 

or agricultural forensic consultant. 

Often, the lack of optimal climatic conditions 

do not allow for pest or disease 

outbreaks. In contrast, the cause of abiotic 

symptoms is more difficult to identify 

and costs time and resources. Once 

pests or diseases have been eliminated 

Finding a Trusted Advisor 

Solving vineyard problems that are 

negatively impacting yield and quality 

can be daunting, especially when you 

are working alone. At some point, you 

may need to consult with an expert. 

Before hiring someone, clear goals need 

to be identified so they can be shared 

with a prospective consultant. First, 

what are the yield and quality goals for 

the vineyard and are they being impacted 

by the problem? Are you trying to 


determine what has reduced vineyard 

performance or what has killed vines? 

Second, do you want solutions to end 

the loss of vines and stop the yield 

decline? Finally, do they have the experience 

needed to help you solve your 

vineyard problem? Are they focused on 

your success or are they just interested 

in selling you something that will “correct” 

the problem? If it is a challenging 

problem, do you feel confident that they 

will tell you the truth if they don’t know 

what the cause of poor growth is in your 

vineyard? If you don’t already have a 

trusted CCA or PCA, it may take some 

time to interview a consultant that you 

feel confident will help you and have 

your success in mind. 

Resources 

There are many useful resources 

available to help figure out the cause 

of peculiar vineyard symptoms. Books, 

websites, blogs and webinars are great 

sources of information for starting your 

investigation. However, be mindful that 

these types of resources may be specific 

to a location, climate, variety, production 

system, etc. that may be different 

from your situation. If your vineyard 

health issue needs immediate attention, 

consider contacting a UCCE Farm Advisor, 

Extension Specialist, CCA or PCA 

that specializes in grape production. If 

your grapevine health issue is caused 

by a pest or disease, experts can help 

develop a management program that 

minimizes crop damage. 

Internet and App resources: 

SoilWeb app: https://play.google.com/ 

store/apps/details?id=com.casoilresourcelab.soilweb 

Books 

Grape Pest Management, 3 rd Ed. University 

of California Publication-ANR 

3343 

Raisin Production Manual, University 

of California Publication-ANR 3393 

® 

Harvesting and handling California 

Table Grapes for Market, University of 

California Bulletin 1913 

Compendium of Grape Diseases, Disorders, 

and Pests, 2 nd Ed. APS Press 




The Grower’s Advantage 

Since 1982 

Effective Plant Nutrients and Biopesticides 

to Improve Crop Quality & Yield 

UC Integrated Pest Management: http:// 

ipm.ucanr.edu/index.html 

ORGANIC 

® 

ORGANIC 

® 

® 

Vineyard Advisor app: 

Contains Auxiliary Soil & Plant Substances 

Plant Nutrients & Adjuvants 

Herbicide EC 

Android: https://play.google.com/store/ 

apps/details?id=edu.tamu.agrilife.VineyardAdvisorApp 

Apple: https://itunes.apple.com/us/app/ 

vineyard-advisor/id1187381601?mt=8 

Botector ® 

Biofungicide 

® 

GARGOIL 

INSECT, MITE & DISEASE CONTROL 

Blossom Protect 

Bactericide 

For more information, call (800) 876-2767 or visit www.westbridge.com 


A New Biocontrol Approach for the 

Reduction of Pierce’s Disease in Vineyards 

XylPhi-PD injections contain bacteria-killing viruses 

that limit losses associated with PD. 

By ANIKA KINKHABWALA | Ph.D., Principal Scientist, A&P Inphatec 

Though vineyard managers continually 

face many challenges 

to optimal productivity, Pierce’s 

Disease (PD) represents a particularly 

formidable threat due to limited options 

for effective prevention and control. 

PD is a degenerative, deadly and costly 

disease of grapevines caused by Xylella 

fastidiosa subsp. fastidiosa (Xff) bacteria, 

Gram-negative rod-shaped microbes 

with characteristic large pili. Though 

hosted by many plant species, these 

bacteria are easily spread to grapevines 

by insect vectors such as blue-green and 

glassy-winged sharpshooters (Figure 

1, see page 41). Xff colonize the gut of 

sharpshooters and are transmitted to 

grapevines as the insects feed on vines. 

Figure 2. XylPhi-PD 100-mL vial (photo courtesy Inphatec.) 

Pierce’s Disease: A Major Threat 

Once inside a grapevine, Xff bacteria 

impede the normal function of xylem 

tissue (transport of water and nutrients 

‘up’ from roots to stems and leaves.) 

This damage induces the characteristic 

chlorosis and scorching of leaves, causing 

early symptoms of PD which mimic 

water stress. However, the insidious 

and cumulative damage caused by PD 

eventually kills entire vines in one to 

five years. 

PD represents a major threat to U.S. 

wine regions, accounting for widespread 

economic damage (e.g., roguing 

and replanting of vines, low fruit 

production, etc.) and costly deployment 

of resources aimed at disease 

moderation. PD has been reported in 

28 California counties, covering most 

of all wine-producing regions. State 

Extension teams in Texas, Arizona and 

Figure 3. Viral bacteriophage particles of XylPhi-PD precisely targeting their bacterial host 

(photo courtesy Inphatec.) 

North Carolina have reported significant 

outbreaks in 2021. Lost production 

and vine replacement has been estimated 

to cost grape producers about $56.1 

million annually as of 2014. Further, a 

2016 survey of nearly 200 growers and 

managers in Napa and Sonoma counties 

revealed that 73% of respondents 

identified PD was one of their top three 

management problems. 

Few methods for controlling and 


® 

We Are Here to Help 

Call: 209.720.8040 

Visit: WRTAG.COM 

Figure 1. Blue-green sharpshooter (top) 

and glassy-winged sharpshooter (bottom), 

two of the main insect vectors for 

spread of Xff (photos courtesy Inphatec.) 

Zn 

treating PD have been made available, 

with efforts historically focused on 

controlling the sharpshooter vector 

(e.g., insecticides, trapping, monitoring, 

inspections) or roguing seriously ill 

vines (rogue, replant), all of which has 

achieved only limited success. However, 

a new option that reduces PD in grapevines 

is now available. 

Fe 

Mn 

Cu 

New Bacteriophage Injection for PD 

XylPhi-PD is a novel, OMRI-listed, 

biological treatment for PD, a cost-effective 

break-through technology 

developed exclusively for viticulture by 

A&P Inphatec (Figure 2, see page 32). 

XylPhi-PD contains a cocktail of viral 

bacteriophages (Figure 3, see page 32) 

that are injected into a grapevine (‘bacteriophage’ 

are bacteria-killing viruses 

that selectively infect bacteria but do 

not infect the eukaryotic cells of plants 

or animals.) These virus particles enter 

and destroy Xff bacteria, thus limiting 

bacterial growth and the xylem-clogging 

damage to the plant. Hundreds of 

phage particles can be manufactured 

inside an Xff bacterial cell after infection 

by a single phage particle. The Xff 

Zinc-Shotgun® is a fertilizer that focuses on micronutrients to satisfy needs of customers seeking high zinc 

with manganese, iron and copper. The micronutrients are completely chelated with natural organic acids, 

amino acids, and carbohydrates that are readily bio-degradable and supply energy to the plant and soil 

microflora. Many soils are low in zinc and also require other micronutrients for the growth of good crops. 

Complete, organically complexed micronutrient package containing 

essential elements to improve plant health and growth. 

The nutrients are readily absorbed by the plant for a faster response. 

Designed to be applied both by foliar application and fertigation 

practices and is also effective when applied directly to the soil. 

Organically complexed with plant based amino acids, organic acids, 

and complexed polysaccharides. 




bacterial cell eventually dies and releases 

all newly created phage particles 

to seek and destroy more Xff bacterial 

cells (Figure 4). 

XylPhi-PD applications are made by 

injection of the product into the vascular 

system of grapevines. Applications 

are made directly into the active xylem 

tissue of the plant using a pressurized 

injection device, the Xyleject Injection 

System (Figure 5). 

XylPhi-PD can be flexibly applied as 

a treatment when disease symptoms 

appear, as a preventative to protect 

growing vines, or whenever conditions 

may lead to disease. As with most any 

disease situation, disease prevention or 

treatment early in the disease process 

provides much better outcomes than 

treatment of later-stage severe infections. 

XylPhi-PD is available in 100-mL 

vials (treats up to 300 mature vines or 

600 young vines.) The product has no 

restricted-entry interval (REI), requires 

minimal personal protective equipment 

(PPE) when used in accordance with 

label directions and is approved for use 

in organic production (OMRI-listed, 

Organic Materials Review Institute). 

Efficacy Overview 

Multiple studies have been conducted 

to support the development and 

commercialization of XylPhi-PD, and 

results have provided much insight 

regarding the product’s efficacy profile 

and use strategies. Brief overviews of 

some of these studies follow: 

Greenhouse pilot study (Texas A&M, 

2014): 

Design: 30 greenhouse grapevines 

inoculated with Xff. 15 vines treated 

with XylPhi-PD once at three weeks 

post-inoculation, 15 vines received only 

buffer. Visual symptoms of PD assessed 

12 weeks post-inoculation. 

Results: XylPhi-PD reduced PD incidence 

by 87%. 

Natural infection field trial (Texas 

A&M, 2015): 

Design: 30 Chardonnay and 30 Cabernet 

Sauvignon vines in an area with 

high natural PD pressure randomly 

assigned to each of the four groups. 

Vines treated zero, one, two or three 

times with XylPhi-PD during the 

summer. 

Results: Disease incidence in the 

XylPhi-PD-3X group was significantly 

reduced by 44% (P = 0.047) compared 

to controls (10% vs 18%). Activity of 

vectors positive for Xff was high during 

the trial period. 

Challenge studies, prevention and 

therapeutic treatment (California 

University, 2017): 

Design: Prevention study – 15 Chardonnay 

and 15 Cabernet Sauvignon 

vines treated with XylPhi-PD and then 

challenged twice with Xff. 

Therapeutic study – 30 Chardonnay 

and 30 Cabernet Sauvignon vines/ 

group challenged twice with Xff and 

then treated zero, one, two or three 

times with XylPhi-PD. 

Results: Prevention – prechallenge Xyl- 

Phi-PD significantly reduced incidence 

of PD symptoms by 75% in Cabernet 

Sauvignon vines (P < 0.10) and 100% in 

Chardonnay vines (P < 0.05) vs controls. 

Therapeutic – three post-challenge 

XylPhi-PD treatments significantly 

reduced incidence of PD symptoms by 

90% in Cabernet Sauvignon vines (P < 

0.05) and 77% in Chardonnay vines (P 

< 0.10) vs controls. 

Multi-year natural infection field trial 

(2017-20; Sonoma, Calif.): 

Design: Two groups of healthy Zinfandel 

vines were tracked in a high 

PD-pressure, organic vineyard for three 

seasons (Ridge, Lytton Springs). One 

group (n=71) received XylPhi-PD three 

times/summer, while controls (n=94) 

only received buffer. 

Results: After three years of treatment, 

vines treated with XylPhi-PD show 

much less PD incidence than control 

Figure 4. Death and rupture of a bacterial cell, 

releasing newly created phage particles to seek 

and destroy more bacterial cells (photo courtesy 

Inphatec.) 

Figure 5. Injection of XylPhi-PD into trunk of 

mature grapevine. Xyleject Injection System 

(Pulse Biotech, LLC; Lenexa, KS) 

vines as assessed by both qPCR (-60%) 

and visual PD symptoms (-72%). Vines 

treated with XylPhi-PD also generated 

higher fruit yields, averaging +1.34 lb/ 

vine (+21%) more than control vines. 

4-site, 3-year, Natural Infection Field 

Trial (2019-21; Sonoma, Calif.): 

Design: A three-year, multi-location 

commercial (Wilbur-Ellis) field study 

evaluated the efficacy of XylPhi-PD 

against endemic PD across four sites 

and three production seasons. The 

extensive research effort began in 2019 

when a study was conducted that involved 

400 vines (300 Chardonnay, 100 

Pinot Noir) at three Sonoma County 

commercial wineries with a history 

of PD (one winery had two test fields) 

(Figure 6). All four commercial vineyards 

were historically high PD sites, 

and despite continual roguing and 

insecticide use in the past, a persistent 

reservoir of Xff remained in the vineyards 

from previous infection cycles. 

Thus, each site included vines with both 

early-stage and chronic/severe PD. 


Xyleject Injection System (Pulse Biotech, LLC; Lenexa, KS) 

Figure 6. Locations of four sites used for three-year field study. 

Figure 7. Study design and timeline for three-year multi-site field study. 

Vines were randomly selected in treatment 

blocks at each site and assigned 

to either of two treatment groups as 

follows: 

-Control (untreated): n=200 (50/site); 

-XylPhi-PD: three treatments (Jun/Jul/ 

Aug); 80 µL of XylPhi-PD injected twice 

in the trunk and once in each cordon (4 

to 6 injections = one treatment); n=200 

(50/site). 

Six petioles from each vine were 

collected in September for analysis by 

quantitative polymerase chain reaction 

(qPCR) and confirmation of Xff 

infection. All study vines were also 

visually assessed by trained observers 

for PD development. Insect traps were 

placed at each study site in an attempt 

to monitor vector pressure. 

A continuation of the same study 

protocol was followed in 2020 and 

2021, allowing two additional seasons 

of treatments and observations for the 

same vines/blocks at the same sites/ 

wineries. In addition, treatments and 

observations of additional vines were 

initiated in 2020 at each site (n=50/ 

site, 200 total), repeated again in 2021 

(Figure 7). As a result, three groups 

emerged from the study for tracking 

and evaluation: 

Vines with three years of treatment 

(three-year treated, n=200) 

Vines with two years of treatment (twoyear 

treated, n=200) 

Non-treated controls (n=200) 

Results 

Comparative outcomes for vines 

qPCR-positive for Xff are summarized 

in Figure 8, see page 36. Under the 

conditions of only mild to moderate 

PD pressure and low vector populations, 

sequential year-to-year use of 

XylPhi-PD generated impressive results. 

Incidence of Xff positivity fell 24% and 

45%, respectively, for vines receiving 

two or three years of treatment compared 

to untreated controls. Improvement 

in the three-year group was 

significant (P < 0.05) vs controls. The 

few vines remaining Xff-positive in the 

two- and three-year groups were chronic 

infections that would be rogued. 



Figure 8. Vines qPCR-positive for Xff, or vines showing visual signs of PD. Summary of four sites in Sonoma County. 


The visual assessment of vines for signs 

of PD was another important study 

parameter, and outcomes (Figure 8) 

were similar to those using qPCR confirmation 

of infection. Vines treated 

with XylPhi-PD for two years generated 

a 27% reduction in visual PD incidence 

compared to controls, while vines 

treated for three years showed double 

the benefit, a significant 54% reduction 

(P < 0.05) of PD incidence. The similarity 

of these data with qPCR results 

suggests that visual assessments can 

help vineyard managers tangibly gauge 

the efficacy of XylPhi-PD. 

Notably, XylPhi-PD continued to 

protect against PD infections at all four 

trial sites for the three years of observations, 

with no new infections detected 

in the three-year treated group. In 

contrast, the control group had ~2% to 

4% new infections. 

Fruit yield was measured at one study 

site (D) at the study’s conclusion in 

2021 (Figure 9, Chardonnay, eight- to 

ten-year-old vines). Compared to 

untreated controls, vines in the group 

treated with XylPhi-PD for three years 

averaged 5.1 lb (+17%) more fruit per 

vine than controls. Vines treated for 

two years were intermediate (3.1 lb, 

+10% more fruit vs controls). 

Usage 

Recommendations 

XylPhi-PD can be 

applied as a preventive 

treatment 

to protect growing 

vines, as a therapeutic 

treatment when 

disease symptoms 

become visible, or 

anytime production 

conditions may lead 

to disease pressure. 

Locations selected 

for application of 

XylPhi-PD can be 

based on the age 

of the plant, the 

pruning style and/ 

or the training system utilized for the 

plant. The product is to be injected into 

the active xylem vascular tissue above 

ground level. Two examples of injection 

strategies appear in Figure 10, see page 

37. On established vines, for example, 

one or two injections can be applied in 

the trunk with an additional injection 

in each cordon or spur. For young, recently 

planted or radically pruned vines, 

apply two or three injections into shoot, 

two to six inches above the ground. For 

all scenarios, the total number of injections 

administered to a vine define one 

‘application’ of XylPhi-PD. 

Figure 9. Average fruit yield for Chardonnay vines at one site 

(D). 

For most production situations (medium 

to high PD pressure), two or three 

applications of XylPhi-PD are recommended 

during each growing season at 

near-monthly intervals (Figure 11, see 

page 37). This frequency of application 

has been demonstrated to provide optimal 

PD control under various levels of 

PD pressure. The volume of XylPhi-PD 

administered can also vary depending 

on the age of plants being treated and 

PD pressure. 

The quantity of XylPhi-PD used in 

XylPhi-PD treatment programs can 

vary based on the number of injections/ 

vine, the concentration of product/injection 

and the number of applications/ 

year. Growers and PCAs have options 

and flexibility to match doses and the 

number of applications to their specific 

conditions and risks. Table 1 summa- 


Table 1. XylPhi-PD dosage options and number of applications per vial (100 mL). 

Figure 10. Recommended XylPhi-PD injection locations. 

Figure 11. Examples of XylPhi-PD application programs involving medium to high PD pressure. 

rizes some of these options and their 

impact on the amount of XylPhi-PD 

used and number of vines treated per 

100-mL vial. 

Treatment Strategies for 

PD Management 

Several recommendations for managing 

PD across an entire vineyard have 

emerged from field use experience with 

XylPhi-PD. These recommendations 

largely depend on the scope and distribution 

of PD in a particular vineyard 

or block. 

As usual, vines demonstrating severe 

and/or chronic PD infection should be 




rogued per IPM protocols. 

Vines appropriate for XylPhi-PD treatment 

should be identified. 

These appropriate vines should be 

treated with recommended doses of 

XylPhi-PD at two or three seasonal 

applications as needed for mature vines 

or replants (per label directions). 

It is the second step, identifying which 

vines to treat, that can sometimes pose 

a quandary for production managers. 

To help in this process, three strategic 

options can offer direction for developing 

a customized plan for vineyard-wide 

PD management. Based on 

evaluations regarding the spread of infection 

and site specifics for a particular 

vineyard or block, a treatment strategy 

can be selected from the following 

(Figure 12): 

Targeted buffer zone: Treat all vines in 

any defined area with high PD activity 

(>2% symptomatic vines) and/or vector 

activity, such as near a riparian area. 

Precision spot: In large areas with few 

symptomatic vines, mark/identify 

affected vines and treat only them and 

their immediate surrounding neighbors. 

Entire block: In large areas with multiple 

scattered symptomatic vines, in the 

presence of vectors, full-block treatment 

is needed to reduce overall PD 

pressure. 

In addition to these three options, the 

duration of treatment (multiple years) 

is also a critical consideration. As 

discussed earlier, field studies have 

demonstrated the cumulative value of 

consistent treatment with XylPhi-PD 

over multiple years for reducing the 

level of PD in a vineyard or block, 

even when under low PD pressure. As 

always, prevention of severe, chronic 

disease is the best approach, and consistent 

long-duration use of XylPhi-PD 

appears to substantially diminish PD 

Figure 12. Strategies and options for treating areas within vineyards or blocks. 

progression and pressure in vineyards. 

Identifying PD 

Some of the visual signs of PD damage 

are presented in Figure 13, including 

characteristic chlorosis (leaf scorching), 

irregular lignification and berry 

shriveling, and ‘matchstick’ petioles. In 

general, PD is likely present in a vineyard 

if the following four symptoms are 

observed late in the season: 

• Leaves scald in concentric rings or 

in sections 

• Leaf blades abscise, leaving petioles 

attached to the cane 

• Bark matures irregularly 

• Fruit clusters shrivel or raisin 

However, damage caused by various 

other diseases, water stress, pests or 

nutrient deficiencies/imbalances may 

produce symptoms similar to those 

caused by PD. Therefore, PD must be 

laboratory confirmed by detection of 

Xff by qPCR testing on late-season/fall 

petioles (e.g., UC Davis Foundation 

Plant Services, Texas Plant Disease Diagnostic 

Lab, Arizona Plant Diagnostic 

Network). 

Conclusions 

PD is an extremely challenging problem 

for wine producers and their consultants. 

A biological control approach 

with XylPhi-PD offers a fresh opportunity 

to help manage PD and limit losses 

associated with the disease. In multiple 

studies, XylPhi-PD treatment of diverse 

wine varietals prompted reductions 


Figure 13. Examples of visual damages caused by PD (photos courtesy Inphatec.) 

in PD incidence and/or severity under conditions of both 

natural and challenge infection with Xff. These favorable 

outcomes distinguish XylPhi-PD as a targeted and cost-effective 

strategy for effectively protecting valuable vineyards 

against PD. 

Always read and follow product label directions. Not registered 

in all states. EPA Reg. No. 93909-1. Operators of injector must 

undergo training and be certified by Pulse and must follow 

instructions in device manual. XylPhi-PD is a trademark of 

A&P Inphatec. Xyleject is a trademark of Pulse Biotech. 

References 

Pierce’s disease research updates. California Department 

of Food and Agriculture. http://piercesdisease.cdfa.ca.gov 

(accessed December 2021). 

Pierce’s Disease. California Department of Food and Agriculture. 

https://www.cdfa.ca.gov/pdcp/Pierce’s_Disease.html 

(accessed December 2021). 

Tumber KP, Alston JM. Pierce’s disease costs California $104 

million per year. California Agriculture 2014; 68(1):20-29. 

Evaluating Potential Shifts in Pierce’s Disease epidemiology. 

California Department of Food and Agriculture. https:// 

static.cdfa.ca.gov/PiercesDisease/reports/2019/CDFA%2015- 

0453-SA%20Final%20Report.pdf (accessed December 2021). 

Field trial report, 2020. Ridge Lytton Springs/A&P Inphatec. 

Data on file 

2020 Field Trial Results: XylPhi-PD for Control of Pierce’s 

Disease. A&P Inphatec Technical Bulletin. https://inphatec. 

com/wp-content/uploaXffds/XylPhi-2020-field-trials-1.pdf 



Additional Environmental Stress Conditions that the product is useful for: 

What is 

Anti-Stress 550®? 

When to apply 

Anti-Stress 550®? 

Beat the Heat & Care 

for Your Crops with: 

Anti-Stress 

550 ® 

Frost & Freeze 

• High Temperatures & Extreme Heat 

• Drought Conditions 

• Transplanting • Drying Winds 

A foliar spray that creates a 

semi-permeable membrane 

over the plant surface. 

Optimal application period is 

one to two weeks prior to the 

threat of high heat. 

Ahern SJ, Das M, Bhowmick TS, Young R, Gonzalez CF. 

Characterization of novel virulent broad-host-range phages 

of Xylella fastidiosa and Xanthomonas. J Bacteriology 2014; 

196:459-471. 

When is Anti-Stress 550® 

most effective? 

The coating of Anti-Stress 

becomes effective when the 

product has dried on the plant. 

The drying time of Anti-Stress is 

the same as water in the same 

weather conditions. 

Texas A&M Research Progress Report, 2014. Data on file. 

Texas A&M Research Progress Report, 2016. Data on file. 

CA 2017 Field Trial Progress Report, 2017. Data on file. 

*One application of Anti-Stress 550® will remain effective 30 

to 45 days, dependent on the rate of plant growth, 

application rate of product and weather conditions. 

559.495.0234 • 800.678.7377 

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Order from your PCA or local Ag Retailer / Crop Protection Supplier 


Delayed Spring Growth and 

Grapevine Production During 

Drought 

By GEORGE ZHUANG | UCCE Viticulture Farm Advisor, Fresno County 

and MATTHEW FIDELIBUS | Extension Viticulturist, UC Davis 

After 2021 grapevine budbreak, we received many calls 

about dead spurs, delayed bud break, stunted shoot growth 

and poor fruit set. In Fresno County, some severely impacted 

vineyards suffered a substantial yield loss. In many cases, the 

problem was delayed spring growth (DSG), and the classic vine 

symptoms include: 

the minimal temperature of the 2020 winter might be lower than 

the last five years’ average according to the CIMIS station data, 

the DSG’s occurrence and severity varied significantly across 

• Delayed and erratic bud break 

• Stunted shoot growth 

• Excessive berry shatter and poor fruit set 

The situation was apparently spread across different grape growing 

regions in California, and UC Davis Department of Viticulture 

and Enology held a virtual grower meeting to discuss it (the 

recorded presentation can be found on the UC Davis AggieVideo 

website.) 

Delayed Spring Growth 

Grapevine DSG is associated with insufficient rehydration of 

the vines and may be due to vascular tissue injury, insufficient 

carbohydrate reserves, excessively dry soil over winter or some 

combination of these factors. Symptoms can result in significant 

yield loss and permanent vine damage, resulting in economic 

hardship for growers. Some vine DSG symptoms are similar to 

other pest/disease symptoms (e.g., vine trunk disease or soil 

pests like nematodes/phylloxera.) However, most vineyards we 

visited had little or no sign of trunk disease or soil pests. Several 

factors this past fall and winter contributed to widely observed 

and severe vineyard DSG symptoms: 

Top left: delayed and erratic bud break from DSG vines; top right: stunted 

shoot growth after bud break from DSG vines; bottom left: Inflorescence 

bloom on a weak canopy; bottom right: Excessive berry shatter and poor 

fruit set from DSG vines (all photos courtesy G. Zhuang.) 

• Ongoing drought and increasingly dry soils, especially 

over winter in vineyards which were not sufficiently 

irrigated postharvest, or during winter 

• Warmer than normal fall temperatures, including a 

particularly warm October 

• A sudden freeze in early November 

According to CIMIS station data at Five Points, October 2020 

was warmer than the last five years’ average and followed a sudden 

freeze event in November (Figure 1), and warmer-than-normal 

autumn is a risk factor for DSG. In addition to the November 

freeze event, October and November 2020 were mostly dry, 

and a drier autumn could make the freeze worse. Even though 

40 Progressive Crop Consultant January / February 2022 

Top left: Selma Pete dead cordon from botryosphaeria canker; top right: 

Trunk discoloration and pie shape canker on Selma Pete from botryosphaeria 

canker; Bottom left: Grapevine decline from nematodes; 

bottom right: Grapevine root galls from root-knot nematodes.

Daily Minimal Temperature (F ) 

vineyards in Fresno County and other parts of California. 

Also, vineyard management, particularly postharvest and 

winter irrigation, could make a big difference on the results of 

DSG even if the ambient weather condition was similar. The 

70 

60 

50 

40 

30 

2020-2021 CIMIS Station at Five Points 

20 

Sep Oct Nov Dec Jan Feb Mar Apr 

Figure 1. Daily minimal temperature from September 2020 to April 

2021 at CIMIS Station near Five Points, Calif. 

- 

Daily Minimal Temperature (F ) 

2020-2021 UC IPM Weather Stations at Fresno Co. 

70 

2020-2021 CIMIS Station at Five Points 

60 

50 

40 

30 

20 

10 

Sep Oct Nov Dec Jan Feb Mar Apr 

Date of year 

Figure - 2. Daily minimal temperature from September 2020 to April 

2021 at five UC IPM weather stations in Fresno County. 

- 

- 

- 

Precipitation (in) 

4 

3 

2 

1 

0 

Precipitation From October to March 

Oct Nov Dec Jan Feb Mar 

Month 

Figure 3. Monthly precipitation from October 2020 to March 2021 

in Fresno County. 

geographic location as well as vineyard microclimate can sometimes 

mean quite different consequences in the face of freeze 

damage. Figure 2 illustrates the variation of daily minimum 

temperatures from five locations in Fresno County. Typically, 

vineyards located on the west side had a lower minimal 

temperature and suffered more freeze damage than vineyards 

located on the east side. Sand Ranch in particular had the 

lowest daily minimum temperature among five locations from 

October to March. 

To make matters worse, Fresno County saw much less precipitation 

during the months of November and December 2020 than 

the last 20 years’ average (Figure 3). These drier months might 

offer the perfect conditions for DSG. Although precipitation 

amount was normal in January 2021, February was yet another 

dry month in comparison to historical averages. Lack of soil 

moisture before bud break is another major risk factor for DSG. 

Grapevine winter freeze damage and DSG have similar symptoms 

and can be difficult to differentiate. Winter cold damage 

or freeze injury damages vascular tissues and can thus interfere 

with water, carbohydrate and mineral translocation, causing 

symptoms similar to DSG. A lack of soil moisture can impair 

vine rehydration, making vines suffer water stress and causing 

DSG symptoms directly. Additionally, vines might be more 

vulnerable to cold injury even though the minimal temperature 

in the past winter, such as 25 degrees F at Sand Ranch, might 

not cause significant freeze damage on most Vinifera grapes. 

Maintain Vine Health 

Vineyard conditions should be considered to avoid DSG and 

possible cold damage: 

• Abiotic or biotic stressed vines (e.g., severe water stress 

and overcrop, nutrient deficiency, pest/disease) 

• Young vines 

• Late ripening and cold tender varieties 

• Certain rootstocks, including Freedom and Harmony 

• Insufficient soil moisture during the dormant period (e.g., 

October to March in the San Joaquin Valley) 

Generally, maintain vine health over the growing season and 

assess soil moisture as the vines enter dormancy, watering if 

needed. Too many clusters with not enough leaf area can weaken 

the vines and deplete the trunk and root’s carbon reserves, 

which are needed to maintain respiration over winter, help prevent 

freezing and nourish the vines as they regrow in the spring. 

To maintain a functional vine canopy, irrigate as necessary to 

support photosynthesis without stimulating excessive growth. 

If pests or diseases are present in the vineyard, such as powdery 

mildew, nematodes, grapevine trunk disease, virus, mites and 

leaf hopper, a good assessment of canopy health is important. 




Grapevines with severe defoliation or small canopies will 

be of great concern, and management should focus on 

better addressing pest and disease problems to avoid early 

defoliation. 

A young vine has its inherent nature of vulnerability due to 

a lack of sufficient carbon reserves. Therefore, severe water 

stress and overcropping should be avoided, and irrigating 

the soil before a freeze event (e.g., late October and early 

November) can be greatly beneficial to provide heat protection 

for young vines. 

This past spring, we noticed some susceptible varieties 

might suffer greater damage from DSG, and that has been 

consistent with the reports from other growers. Chardonnay 

and Pinot gris have been reported frequently on 

DSG, although both varieties are also susceptible to winter 

freeze. 

Top Left: soil auger. Top Right: Soil water potential sensor. Bottom: Soil water 

volumetric sensor. Many tools can provide great benefits for assessing soil 

moisture and help growers determine whether or not to irrigate. 

Rootstock can also play an important role in DSG. Certain 

rootstocks (e.g., 5BB and Freedom) are more susceptible 

to DSG than others (e.g., 1103 P), according to results of 

UCCE rootstock field trials in different growing regions 

of California. Thus, growers who have the susceptible 

rootstock might want to take extra care of the vines, such 

as irrigating the soil during the dry winter, so that the risk 

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20% yield loss has been reported for some vineyards in Fresno 

County in 2021, and DSG might play a large role in it, although 

the record summer heat and seasonal variation could also result 

in loss. Finally, the consequence of DSG on Fresno vineyards 

varied greatly. Some vineyards appeared to be significantly 

stunted after budbreak and later fully recovered due to irrigation. 

Some vineyards might suffer multi-year yield loss due to 

the weakened canopy and few desired canes to prune. 

Petite Verdot on 5BB rootstock at front and Cabernet 

Sauvignon on 1103 P rootstock in back. 

of potential DSG might be minimized. 

Manage Soil Moisture 

Last but not least, lack of soil moisture might be the most 

important yet manageable factor contributing to most DSG 

farm calls. As discussed previously, drier October, November, 

December and January months posed a great risk of DSG as 

well as inhibited rehydration of the vines, which can also lead 

to a greater risk of freeze damage. However, water availability 

during the drought years might be significantly reduced or 

expensive. 

Therefore, irrigation during the drought years can become 

the dilemma. Growers need to balance the cost and reward of 

irrigation vs. no irrigation during drought years. Greater than 

In the face of upcoming potential drought, growers can use 

multiple tools to reduce or eliminate the effect of soil moisture 

deficit. Many tools (e.g., shovels, soil augers, moisture sensors) 

can provide great benefits for assessing soil moisture and help 

growers determine whether or not to irrigate. Weather stations 

can also provide great amounts of information regarding the 

minimal ambient temperature as well as the amount of local 

precipitation, since temperature and precipitation can vary 

greatly from one vineyard to another. UC IPM has seven weather 

stations in Fresno County and one station in Madera County 

in cooperators’ vineyards, and those stations can offer both 

temperature and precipitation amount, serving the growers 

whose properties are nearby the station. 



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Bayer CropScience LP, 800 North Lindbergh Boulevard, St. Louis, MO 63167. ©2022 Bayer Group. All rights reserved.

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