Oregon State University



Event Details

Oregon Wine Research Institute Seminar Series

Dr. Glenn McGourty, Winegrowing & Plant Science Advisor, UC Cooperative Extension

Tuesday, August 8, 2017 12:00 PM - 1:00 PM

Understanding the Ecology of Ice Nucleating Bacteria and Integrated Protection Strategies to Prevent Freeze Damage in Northern California Vineyards

Dr. Glenn McGourty, Winegrowing and Plant Science Advisor, University of California Cooperative Extension 

Frost occurs in vineyards when temperatures fall below 32 degrees F and ice nucleating bacteria are present to catalyze the formation of ice crystals on green tissues. Laboratory studies prove that in the absence of these bacteria, plant tissue can supercool to as low as 22 degrees F.  Pseudomonas syringae is most commonly associated with frost events.  In initial studies, we have controlled ice nucleating bacteria on grape vine tissue and reduced the potential for freezing damage.  Our present research includes two large replicated trials covering 6 acres, one at Roederer Estate US in the Anderson Valley, and the other at Beckstoffer Vineyards in Lake County. We are comparing sprays of cupric hydroxide (0.75 lbs of copper oxide in 25 gallons of water) to an unsprayed control. These treatments are being applied to grape vines in sub-plots with the presence or absence of vineyard floor vegetation, a known source of ice nucleating bacteria that can contaminate emerging green grapevine tissue. In the laboratory, initial results are showing that freezing temperature of the leaves treated with copper was significantly lower than the control treatments. Treated leaves froze between 28 to 30 o F.  Separate trials are following the acquisition of ice nucleating bacteria on vineyard floor cover crops throughout the season. There are significant differences in the rate of acquisition and total bacterial numbers on the cover crops. Finally, we are investigating whether we can introduce the bacterium Pseudomonas fluorescens ‘A506’ as a colonist into vineyards which will compete with ice nucleating bacteria to prevent freezing. In initial trials it appears that we can successfully establish this bacterium, and hopefully, it will help to protect vines from freezing. Manipulating the microflora of vines may be a possible way to frost protect with far less expense and energy than sprinkler systems and wind machines in mild frosts. The equipment and technology to protect vines with our approach is already available in many vineyards.  

To view live online, visit: http://live.oregonstate.edu/. Please note, the event will not be available until 12:00 PM on Tuesday, August 8.  

Live chat will NOT be available, however, online live participants can submit questions during the seminar to denise.dewey@oregonstate.edu, and they will be answered at the end.  


Kidder Hall (campus map)
2000 Campus Way
Denise L. Dewey
denise.dewey at oregonstate.edu
Oregon Wine Research Institute
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