Independent Grape Growers - Paso Robles Area
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September Blog – Biological Soil Fertility & Late Season Botrytis

Special Blog Post on Fall Concerns





Cristy Christie
Black Diamond VermiCompost
Post Harvest Biological Soil Fertility


Grape growers around the globe are recognizing the need to add nutrients to their vineyards after harvest.  In-season tissue analysis determines post-harvest soil and foliar applications of nutrients to help the vines build and store the carbohydrates and sugars. These nutritional needs have been well documented by universities and growers alike from South Africa to Australia New York to here on the West Coast.  As grapes enter dormancy, the maximum crop potential for the next growing season has most likely already been determined.

What else can growers do to add value to their pocketbook next year? Not only is early season growth potential determined by the nutritional reserves that have been built up prior to leaf drop (photosynthesis), root activity is also largest immediately post-harvest. But what is it that makes the root systems active and vigorous? A large part of the answer is found in the soil life.  Call it productive soil, healthy soil, microbial soil life or the soil food web, it’s all the same. Plants have amazing communication skills. The vast majority of soil microbes have yet to be identified, but what we do know is when a large variety are added to soil, the entire plant, including fruit, above and below ground, benefit.

[Excerpt] Extensive communication occurs between plants and microorganisms during different stages of plant development in which signaling molecules from the two partners play an important role. Fungal and bacterial species are able to detect the plant host and initiate their colonization strategies in the rhizosphere by producing plant growth-regulating substances such as auxins or cytokinins. On the other hand, plants are able to recognize microbe-derived compounds and adjust their defense and growth responses according to the type of microorganism encountered. You may want to re-read that a time or two to begin to realize how complex and fascinating the conversation is that takes place between soil microbiology and a plant’s root system. Minerals and microbes must both be present for the cycle to be effective.  If you want to learn more, the entire article can be found here.

There are dozens of studies and abstracts on the value of healthy soil microbiology, but suffice it to say that it’s just good farming practice to add a good dose of it with post harvest nutrients.  By adding teas and/or extracts, nutrients stored in the bodies of the microbial life are not lost through irrigation to contaminate ground water. Hair-thin fungal hyphae, or tentacles, wrap around soil particles in their search for food, forming aggregates that create great soil texture. Both the fungi and soluble organic matter are held in the soil. Bacteria release a sticky mucous that enable them to cling to solid particles of mineral and organic matter, ensuring they too remain in the soil and, like the fungi, aid in the formation of aggregates.

Properly made compost teas and extracts, when using vermicompost as the base, adds a plethora of soluble plant nutrients and growth compounds, a diverse microbial population, and organic matter that provide an ongoing supply of nutrients. The plant receives a consistent and reliable food source when bacteria and fungi feed on the organic matter. This below ground surface microbial activity releases some of the nutrients to the soil and retains others for their own energy and reproduction. When nematodes and protozoa in turn feed upon them, the nutrients stored in the bacterial and fungal cell walls are released to the soil in a highly soluble plant available form. When we feed the soil, the soil feeds nutrients to the plant.

You can learn the differences between aerated compost teas and extracts here. Supply the minerals and nutrients your vines need, add tea or extract to that solution and let nature go to work while you take a short break from the vineyards task list.

Since you have read this far…(thank you!)…I hope you will take advantage of the offer that follows. It’s a substantial discount, and we are confident that your vines will wake up next year with healthy vigor and a stronger immune system.



Dr. Lowell Zelinski
IGGPRA President

As we move into fall, most diseases of grapes, especially Powdery Mildew are no longer an issue. This assumes it has been prevented and/or controlled in the past and is not a concern right now.

But we are not out of the woods yet. There is another fungal disease of grapes which commonly occurs in the fall, but may be a pest all season long, namely Botrytis. This article will discuss the ecology and control of Botrytis in wine grapes in the Paso Robles area.

The botany of Botrytis is complex and is not really worth going into in this article. It has two different names, one for the sexual stage, which is rare and one for the asexual stage which is very common. Botrytis can infect almost all dicots (broad leaf plants) and many monocots (grasses). If you have any weeds in your vineyard they are probably a host for Botrytis. This includes the Oak trees that occur throughout Paso.

Botrytis can also survive in the soil for many years. Basically, there is no way to avoid the inoculum, it is everywhere, all the time. If this is the case, how does it not cause major problems all of the time? The answer is that it is the environmental conditions plus plant conditions that allows Botrytis to thrive. Other than on grape flowers and ripe “damaged” fruit Botrytis will not reproduce unless environmental conditions are sufficient for its growth. Botrytis needs a source of nutrients on which to feed. Flowers and damaged berries provide that source of nutrients. The environmental conditions where Botrytis can grow and thrive are fairly broad, temperature can go almost down to freezing and as high as 85 and it will do just fine. Botrytis also likes high humidity’s and even free water (like rain and heavy dew). The high humidity will most likely occur inside clusters, where after a fall rain event water will accumulate and is very difficult to get rid of.

Condition that do not favor Botrytis are dry weather, open clusters, open canopies, windy weather, low humidity, intact fruit (no damage to berry walls by birds and/or wasps).

Botrytis infected fruit is a problem on the wine making side also. Which is why so many wineries will not accept fruit with high levels of Botrytis. One the issues on the winery side is that Botrytis will convert many of the simple sugars (glucose and fructose) to more complex forms which can not be fermented. This cause fermentation to stop before the desired level of alcohol is reached. Additionally, Botrytis can release a chemical that actually kills the fermentation yeasts, which can cause stuck fermentations, further exacerbating the low alcohol problem. It also causes problems in color stability and in white varieties it can lead to browning of the juice/wine. Finally, off flavors and aromas can results in wines made from grapes high in Botrytis.

How is Botrytis controlled in the Paso area? I know this all sounds like doom and glum but actually Botrytis is only a minor problem in Paso. A major reason is our variety selection. Pinot noir can easily get Botrytis because of its thin skin characteristic (actually, the movie Sideways was right here). We also have fairly dry harvest seasons. Recall, that Botrytis need either free water or high humidity to really become a problem. The only times I’ve had an issue is when the zinfandel grapes would not sugar up and harvest was delayed until mid-November. Of course, it rained enough a few weeks before harvest that the inside of the cluster got wet and didn’t dry out. This caused two problems, the free water needed for Botrytis was available, and the berries swelled and, especially on the insides of the cluster the berry skin ruptured and therefore the fruit was no longer intact.

Finally, I have found that a fungicide spray just prior to berry closure (the time when the berries begin to touch each other) with a material that has efficacy against Botrytis has been beneficial. This has to planned month ahead of potential problems but in my experience it has been worthwhile.

Dr. Doug Gubler

There are times when events happen that are both sad and profound. One of the few UC professors who did applied as well as basic research passed away last week. Dr. Doug Gubler, UC Plant Pathologist was both amazing in his extension service to the grape growing industry throughout California but also in the basic understanding of grape diseases throughout not just California but throughout the world. He will be sorrily missed. He was a friend and an amazing source of information for many many years.

Please read the following article from Wine Business.

UCD Grapevine/Plant Pathologist Doug Gubler Dies at Age 72
by Ted Rieger
July 24, 2018

University of California extension plant pathologist Dr. Doug Gubler, perhaps best known to the wine and grape industry for his major contributions in the management and control of grapevine powdery mildew, died July 19 at age 72, reportedly from a heart attack. A faculty member with the UC Davis (UCD) Department of Plant Pathology since 1983, Gubler retired from UCD in June 2016, but remained active as a speaker at industry meetings and continued with research and consulting activities.

As a UCD plant pathologist, Gubler worked with multiple crops as a specialist in trees, vines and small fruits. He was a renowned scientist in the grape industry for his extensive knowledge of the epidemiology, management and control of grapevine fungal diseases, notably powdery mildew, Botrytis bunch rot, and grapevine trunk and canker diseases.

With research colleague Dr. Carla Thomas, he developed the Gubler-Thomas Powdery Mildew Risk Index, linked with vineyard weather stations to monitor and evaluate conditions favorable to powdery mildew growth based on vine canopy temperature. The powdery mildew index is commonly used by grape growers for deciding when to begin fungicide spray applications each season, and for proper timing of applications during the growing season.

His work on grapevine trunk diseases, and his lectures on the topic, helped growers understand that trunk disease, most commonly known as “Eutypa dieback,” could actually be one of several fungal diseases, and that over 20 canker fungal species are found in California. In addition to Eutypa dieback, other trunk diseases include Bot canker, Phomopsis dieback and Esca. His research on the timing and conditions leading to vine canker infections from fungal spores helped advise growers on practices such as late season pruning and “double pruning,” and the application of materials to pruning wounds to prevent infection, that are often used today. Gubler’s research group also showed that leaf removal could be effective for the control of Botrytis bunch rot and to help reduce powdery mildew.

Gubler was a frequent speaker at industry meetings and logged many miles throughout California each year in his extension duties to visit and assist growers in the field. He was a collaborator and a friend with many farm advisors and commercial grape growers.

In a recent e-mail sent to her grower constituents about Gubler’s passing, UC Cooperative Extension Central Sierra farm advisor Lynn Wunderlich said: “I first met Doug when I was a graduate student at UC Davis in 1994. His warm and jovial personality touched so many students, growers, and farm advisors. I collaborated with him and his lab for many years on apple scab trials in El Dorado County and later asked for his assistance to place the grape powdery mildew weather stations in Foothill vineyards. He was a popular guest speaker at my Foothill Grape Day many times. He loved his work and was always willing to come up and help with a diagnosis or problem. He will be greatly missed by all who knew him.”

Gubler also regularly conducted trials to evaluate new and existing fungicide application materials for their efficacy in controlling fungal diseases and to monitor disease resistance to fungicides. He collaborated with Clarksburg grape grower John Baranek for 30 years in one of Baranek’s Chardonnay vineyards to evaluate as many as 90 different treatments each season to test synthetic, biological and organic fungicides, and different combinations of them, for powdery mildew control. This vineyard then hosted an educational field day each season for growers to inspect the vines and grape bunches for the results of each treatment.

Gubler was an active member of The American Phytopathological Society (APS) that honored him in 1998 with its “Excellence in Extension” Award, and in 2009, as an APS Fellow. According to biographical information posted on the APS website, Walter Douglas Gubler was born January 28, 1946 in St. George, Utah. He graduated from Utah State College with a B.S. degree in botany in 1970 and received an M.S. degree in plant pathology from the University of Arkansas in 1974. He arrived in Davis in 1974 where he worked as a post-graduate research plant pathologist while also beginning studies toward a Ph.D degree in plant pathology that he received from UCD in 1982. He worked as a research scientist with the Campbell Soup Company at their research facility in Davis for one year before joining the UCD Department of Plant Pathology in 1983.

News from CAWG (California Association of Winegrape Growers)

Here is an article that appeared in the CAWG newsletter on 3-15-18

It talks about GWSS (Glassy-Winged Sharp Shooter) and PD (Pierce’s Disease). These are not currently a problem in the Paso area – but are a serious problem in other parts of the state.

Government Relations Capitol Report

The Pierce’s Disease/Glassy-winged Sharpshooter (PD/GWSS) Board is a model for how government and the agricultural industry can successfully work together to protect crops. However, the PD/GWSS program is facing a potential federal budget cut that threatens its continued existence.

The president’s proposed budget provides for a substantial cut, $13.5 million, in federal funding for the PD/GWSS program. Such a reduction in federal funding would, for all intents and purposes, result in a shutdown of the program, which has proved highly successful and important for California winegrape growers. The California Department of Food and Agriculture (CDFA) has requested $25 million in federal funding, the same amount requested last year. CAWG will work closely with CDFA to encourage support from the California congressional delegation for the request.

Winegrape growers have invested millions in the successful eradication of the disease and the vector. Continued trapping throughout the state will indicate if/when there are any reintroductions. Without adequate funding, the PD/GWSS program will have to decide which regions are most at risk and focus only on those regions. This is dangerous, as an infestation of Pierce’s disease anywhere in California threatens winegrapes all over the state.

Last year CAWG was successful in gaining $5 million in new state funding for the PD/GWSS program. This year CAWG will continue the effort of funding this critical program.

In addition to PD/GWSS funding, CDFA and CAWG are also seeking $6.55 million funding for European grapevine moth (EGVM) surveillance in California. Continued funding for surveillance activities is critical to ensuring timely response and eradication in the event of an EGVM reintroduction to the state.

— Michael Miiller / / 916-379-8995

Richard Sauret, IGGPRA President Emeritus has passed

As the current president of IGGPRA it is with deep regret we announce the death of Richard Sauret. He died in a car accident on Saturday, September 30th at 10:30 pm.

Richard Sauret with his favorite Zinfandel

Richard was instrumental in the development of IGGPRA, was President of IGGPRA for many years and will be greatly missed. The time he gave to the grape growers of the Paso area was truly amazing. I can not tell you how many times I saw him at events for grape growers in the Paso area acting as a volunteer and in general helping out. I was truly impressed. He will be missed by lots of people.

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September Seminar Recap

Hello All,

A few years ago, the IGGPRA Board committed to increase the number of Seminars and align the topics to the grape growing cycle. We’ve been successful with that approach and typical attendance ranges for 40-80; member and non-members alike.

In 2017, we determined that there were many topics and issues in the grape growing business that were not necessarily related to the growing cycle but of interest to our members. While we always try to have at least one speaker for the grape growing process at each seminar, we are also trying to bring topics that will expand our members understanding of other aspects in the wine and grape growing market.

The September 20th seminar was a good example of that, and here are the

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CAWG Webinar: Joint Liability – Growers and Farm Labor Contractors

Tuesday, APRIL 25 from 10-11 A.M. – Register Here!

For generations, growers have used farm labor contractors (FLCs) to supply workers when needed for various vineyard tasks. While the FLC has primary employer responsibilities, various legal decisions and legislation – such as AB 1897 – now make the grower jointly liable for issues such as unpaid wages, H-2A visa programs, MSPA and worker transportation, and worker safety and workers compensation insurance. It is increasingly critical for growers to have an understanding of the liability shared, and the need to evaluate and monitor their FLCs on compliance issues. The webinar is presented by Lupe Sandoval, managing director of the California Farm Labor Contractor Association.
Learn more about:

* Understanding joint liability
* Factors that increase the potential for joint liability claims
* Legal requirements and best practices to manage joint liability

* Resources to managing joint liability

Please note: Any vineyard management company that provides workers to a grower or other entity, is, by law, a farm labor contractor and must be licensed by the Department of Labor Standards Enforcement.

Smoke Taint Remediation in Finished Wines

MAV logo PMS Colors HiRes 4x2.jpg

By: Bob Kreisher, President – Mavrik N.A (

For Remediation Services* please contact:

Matt Zinkl, Product Marketing Specialist

Phone: 707-228-0442 (cell), Email:

Smoke Taint From Wildfires Update: What Do We Know Now?

Smoke taint is an annoying obstacle to making the best wine possible from the grapes you have.  But it can be overcome with patience and determination.

What is smoke taint?

Measurement of guaiacol and 4-methylguaiacol is a convenient and reliable way to determine the likelihood of smoke taint. It correlates well

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Smoke Taint and You

What to do when smoke gets in your vines
By: Becky Zelinski

When wineries ask you how you knew whether or not smoke taint has affected your vineyard, it’s best to be know the answers. Growers can find out how to be prepared at the September IGGPRA (Independent Grape Growers of the Paso Robles Area) seminar to be held at La Quinta Inn & Suites on Wednesday, September 21, 2016 from 1 p.m. to 3 p.m. In addition to smoke taint, the latest updates on Red Blotch and Bunch Rot will be discussed.

Like it or not, the California Central Coast has been affected by its share of smoke in 2016. It’s difficult to know at this point which vineyards have been affected with smoke taint and to what degree. Therefore, the million-dollar question on the minds of every grower is: has my fruit been affected; and if so, to what degree and what does it mean?

The short answer is: it’s complicated. Believe it or not, smoke taint is variable from vineyard to vineyard and even within a vineyard. The taint is caused by a

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European Grapevine Moth eradicated!

This is great news!

European Grapevine Moth Eradicated From California

Farmer Worker Overtime Bill Gets New Life – Your Help Needed!

Agriculture celebrated a significant legislative victory on June 2 when the California Assembly defeated AB 2757 (ag overtime bill). The defeat of AB 2757 was the culmination of a concerted effort by farmers across the state to urge the defeat of this bill that was a bad deal for farmers and farmworkers. Regrettably, the author of AB 2757, Assemblywoman Lorena Gonzalez (D-San Diego), has resurrected the bill in another form – and California’s farmers must once again go to battle.

Through legislative sleight-of-hand, Gonzalez was able to magically reach across the boundary that divides the Assembly from the Senate and amend another bill, AB 1066, which had been idling in the Senate Education Committee. Using legislative tactic referred to as “gut-and-amend,” Gonzalez was able to delete the contents of AB 1066 without any vote of the education committee, which had jurisdiction over AB 1066, and insert the contents of the recently defeated AB 2757.

The newly reconstituted ag overtime bill, AB 1066, now awaits referral to the Senate Committee on Labor and Industrial Relations.

AB 2757 was defeated on the Assembly floor by a margin of three votes. When Gonzalez resurrected the bill as AB 1066, she single-handedly nullified the Assembly’s vote, making clear that the labor union agenda should trump the collective wisdom of the Assembly.

CLICK HERE to read a the complete letter written by California Association of Wine Grape Growers (CAWG) President John Aguirre to the entire CAWG membership.

CALL TO ACTION: Please reach out to your state senator and assembly member as soon as possible to inform them of what has transpired. Please keep the fight going by making phone calls, sending emails, and coming to Sacramento to talk to legislators. Thank you.

State Senator Bill MonningSan Luis Obispo District Office
1026 Palm Street, Suite 201
San Luis Obispo, CA 93401
email link
Phone: (805) 549-3784
Fax:  (805) 549-3779

35th District Assemblymember Katcho Achadjian – San Luis Obispo District Office
1150 Osos Street , Suite #207
San Luis Obispo, CA 93401
email link
(805) 549-3381
(805) 549-3400 fax

30th District Assemblymember Luis A. Alejo – Salinas District Office
100 West Alisal Street, Suite 134
Salinas, CA 93901
email link
(831) 759-8676
(831) 759-2961 Fax