LCWC Cosponsors Successful UCCE Lake and Mendocino IPM Seminar

Over 80 growers, vineyard consultants and pest control advisors gathered at the UC Hopland Research and Extension Center to get updated on a broad range of pest management topics at the UCCE Lake and Mendocino IPM Seminar on Friday, November 16.

Matt Daugherty, Ag Biologist with the Mendocino County Department of Agriculture gave a presentation on Respiratory Protection Regulations. The talk included information on pesticide label regulations for respiratory protection, different types of masks, employer requirements for fit tests, medical checks, record keeping and other regulations around the need to protect workers from particulate matter and volatile chemicals.

Dr. Kaan Kurtural, UC Davis Extension Viticulturist, gave a summary of how grape vines respond to Red Blotch Virus infections, explaining how sugar accumulation occurs in leaves of infected plants, but doesn’t get translocated to fruit. Affected vines often fail to reach acceptable levels of sugar and color in the fruit to make good wine and ultimately the vines need to be replanted. There still is no certainty about vectors of the disease and the epidemiology.  It is clear that infected propagation material is a key problem in the movement of this virus.

UCCE Farm Advisor Dr. Kari Arnold talked about how leaf roll virus moves around by both propagation material and mealybugs. It is possible to stop the spread of the virus, but it requires a concerted effort of neighboring vineyards to remove infected material, replant with clean material and work together in a coordinated way to keep areas clean. There are successful examples of this in Napa Valley.

UCCE Farm Advisor Dr. Gabriel Torres gave an overview of plant parasitic nematodes that attack grape roots. He described how the nematodes are sampled and counted in the lab. He also discussed control methods using an IPM approach.  Finally, he reviewed the most commonly planted grape vine stocks and their relative resistance to different nematode species.

UC Riverside Extension Entomologist Dr. Houston Wilson gave an update on the Virginia Creeper Leafhopper (VCLH) Area Wide IPM Project.  The pest is not expanding its range very much. Attempts at biocontrol are not going well, as few parasitized eggs were found in the 2018 growing season.  More rearing and release of the parasitoid Anagrus daanei would help to improve natural biocontrol of the VCLH, but at the moment, there is no research funding and no commercial interest in rearing this insect. Growers and PCA’s now have a good sense of how to control the VCLH in terms of timing of sprays and damage to crops have lessened compared to previous years.

UCCE Farm Advisor Lynn Wunderlich gave a presentation on maximizing the effectiveness of spraying. Adjusting spray rig pressures, using the right nozzles, calibrating rates and checking to see if your sprayer is getting good coverage in the canopy were all covered.

UC Berkeley Plant Pathologist Dr. Steve Lindow updated the ongoing research on controlling ice nucleating bacteria with copper and competitive bacteria as a strategy to prevent frost. Ice nucleating bacterial numbers were far greater in the research plot in Anderson Valley compared to the plot in Lake County in Red Hills. This is probably due to more surrounding vegetation and  earlier bud break in Anderson Valley compared to Lake County where a similar test plot had much lower numbers of ice nucleating bacteria during bud break. Dr. Lindow also discussed new approaches in controlling Pierce’s Disease that he is working on, including manipulating quorum sensing and introducing competitive bacteria with wetting agents through the foliage that prevent the causal organism Xylella fastidiosa from causing disease, even though it may be present.

Glenn McGourty covered for Dr. Monica Cooper’s presentation on powdery mildew fungicide resistance in the North Coast. There is significant and wide spread powdery mildew resistance to the FRAC 3 QoI (strobulurin) fungicides found in our region, even in organic vineyards that have been treated only with sulfur.  This is probably due to the fact that a single allele in the powdery mildew organism is responsible for resistance. Rotating fungicides through the FRAC groups is critical—you should only apply 1 fungicide from each group in a year, and continue to use sulfur in your program if at all possible.

Lynn Wunderlich presented Dr. Cooper’s presentation on Vine Mealybugs.  This is an extremely serious pest that fortunately is not found in Lake or Mendocino Counties as this time. The ability of the insect to live beneath bark of the vines makes it very difficult to control. IPM programs were presented, including the use of insecticides, insect growth regulators, biocontrol and pheromone confusion.  Control of this insect is very expensive regardless of the program selected, costing as much as $500 per acre. An active exclusion program is underway in both Lake and Mendocino Counties by the Ag Commissioners that includes inspection of nursery stock, and trapping (with the help of the UCCE Mendocino County office.)

UCCE Farm Advisor John Roncoroni discussed the most troublesome resistant weeds including annual ryegrass, mare’s tail, and relatively recently found weeds like sharp point fluvellin and stink week that threaten North Coast vineyards. He also covered some of the strategies needed to control these weeds and how timing and vineyard conditions are critical to successful weed control programs.

The conference was held in the very comfortable Rod Shippey Hall with breaks and lunch provided by caterer and local gal Beth Lyon Keiffer, a great wine country chef. LCWC Board Member Broc Zoller described the meeting as “one of the best!”

Ed note: This article was written by UC Cooperative Extension Viticulture Advisor Glenn McGourty, December 2018


    Grower Conversation Series: Winegrape Wednesdays 4:00 pm
    Grower Conversation Series: Winegrape Wednesdays @ The Mercantile
    Jul 17 @ 4:00 pm – 6:00 pm
    Grower Conversation Series: Winegrape Wednesdays @ The Mercantile
    You are invited to attend the Grower Conversation series hosted by Lake County Winegrowers. This series aims to connect growers, buyers, and industry experts to discuss the climate of today’s market. Each conversation will feature[...]
        Skip to content