Independent Grape Growers - Paso Robles Area
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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.

Richard Sauret Memorial

UPDATE 10/12/17: The Memorial has been planned please CLICK HERE for more information and to RSVP.

IGGPRA in coordination with PRWCA is planning a memorial service for Richard Sauret, sometime in very late October or early November.

Please watch your email inbox for more info.

We miss him

If you feel like you are missing info – call me at 286-6544

Lowell Zelinski
President, IGGPRA

European Grapevine Moth eradicated!

This is great news!

European Grapevine Moth Eradicated From California

Vine Mealy Bugs and Lorsban

Just a quick update about two important topics.

I am seeing infestations of vine mealy bug (VMB) in vineyards in the Hog Canyon area of San Miguel. This is a very serious pest! Check out the UCIPM website ( for more information.

I think all growers need VMB traps at about 1 per every 10 acres. It is all over the AVA so don’t think you are immune. I know that Buttonwillow warehouse and CPS carry the traps – and will even monitor them for you (for a price). The cost of control is about $100 / ac. Not insignificant and it can run much higher. If you are organic or biodynamic – it is even more important that you begin trapping as soon as you can. If there is one pest that will make you have to switch away from organic it is this one.

The second thought is on the use of Lorsban (or CHLORPYRIFOS). The UC website recommends this material as a dormant spray for VMB. I recommend that you DO NOT use this material. The director of the Department of Pesticide Regulation (DPR) recently issued this request, ( and I think it is valid

Additionally, If you do use Lorsban (or CHLORPYRIFOS) you will be moved from Tier 1 to Tier 2 by the Regional Water Quality Control Board Ag Order. The reporting requirements are much greater for Tier 2 than Tier 1 – and you really don’t want to go there.

Another update soon about Red Blotch Testing. There is now a “quick” test that can let you know if you have it or not.

Powdery Mildew Alert


Lowell's Corner

Powdery Mildew (PM) is a fungal disease of many plants but for us it is important because it is our most common disease. It is easily controlled – IN ADVANCE OF INFECTION and It can be controlled after infection but this is much more difficult.

PM over-winters on grape vine woody tissue such as cordons, and therefore the infectious parts are available immediately after budbreak. The new green tissue can be infected as soon as it appears.

The current weather is ideal for PM development. If we have six hours of temperatures between 65 and 80 degrees per day then the conditions for PM growth are ideal. I am worried that with conditions being this ideal so early in the season – that many people will miss the very first application of preventative PM control materials. And a light rain or even heavy dew can make things worse.

There are many great materials available and your PCA’s , Farm Supply, Buttonwillow Warehouse, Crop Production Services and private PCA’s will know how to advise you.

The biggest concern it not to get behind. This maybe a year where it is very difficult to catch up!

Cold Injury In Grapes

Cold injury in grapes is more than just frost damage in the spring or the fall. This brief article will discuss the various aspects of cold injury and offer a few suggestions of ways to reduce the risk.Lowell's Corner

Frost damage is very easy and disconcerting to see, especially if it is in your vineyard. In the spring time in Paso there is a risk of frost until May 31, and the vines are susceptible any time after bud break. I am writing this on March 2nd and at least a few vineyard in the Paso area have started to bud out. The first “leaf” I saw was on February 29th in a Westside Syrah block and I also saw leaves on a very few Grenache vines in a different vineyard. These will be the blocks I am most concerned about.

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Limiting toll of trunk diseases calls for timely pruning and protection

Written by Greg Northcutt reporter for Western Farm Press                             Wed, 2015-10-07 10:36


In just about every case, infection with fungi that cause yield-robbing trunk diseases is more a matter of when rather than if in California vineyards.

These diseases include Esca, Botryopshaeria dieback (also known as Bot canker, the most common and widespread trunk disease in California and one of the most aggressive trunk pathogens), Eutypa dieback and Phompis dieback. Although caused by different types of fungi, these diseases share several common symptoms – dead spurs, stunted shoots and zones of rotten wood inside the trunk, called cankers. In fact, usually, more than one of these pathogens can be found in

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September’s Seminar Info

Thank you everyone who joined us at September’s Seminar- we had a great turn out and learned a lot from our 4 speakers. Thank you also to Vina Robles for letting us hold the seminar at their winery.

For those who couldn’t make it we are happy to share with you the presentation slides from the NRCS and Dr. Lowell Zelinski.


Topics & Speakers:

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Lowell’s Corner- What went wrong

Lowell's Corner


September 2015


For most of us – whether you know it or not yet – this year’s grapes yields will be less than stellar. My early indications are yields being between 50 and 0% of normal. Yes I said zero. I manage a block of Sauvignon Blanc which usual produces 20 to 30 tons – this year it was 13. I’ve heard of a block that usually produces between 25 and 40 tons of Syrah being harvested and delivering less than 2 tons.

I know of a Cabernet Sauvignon block were the insurance adjuster said we don’t even need to harvest it – 100% loss. What do we tell the winery?

The big question is WHY. I think there are many reasons. Not the least of which is

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Times – They are a changing – Part II

Times – They are a Changing (again)

Lowell’s Corner

November 2014

 In the last Lowell’s Corner we talked about legislation (AB2453) that, if signed by the governor would move the water users of the Paso Robles Groundwater Basin (PRGB) along the path of forming a California Water District for many areas that overly the PRGB. Certain overlying areas are excluded like the City of Paso Robles and the portion of the basin in Monterey County amongst others.

That bill was signed and we are waiting for it to be referred to the Local Agency Formation Commission (LAFCO) for approval. It can be referred to LAFCO in one of two ways.

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