Everyone who I know in the wine industry calls the start of this season one for the records!  Following nearly 0 precipitation in December and January, we sort of had a normal February and March, which brought rainfall to 18.3 inches for the season compared to  normal precipitation of around 37 inches. So, the good news is that the soil profile is charged and we probably won't need to irrigate until June if weather is not extremely warm. That is good, because there really isn't quite enough water in our ponds and the Russian River to do much frost protecting this year.

The other good news is that it hasn't been very cold, and so far, we haven't had to frost protect a single time in the Ukiah and Hopland area. I'm pretty sure the that the reason for this is that I am doing a trial with the "Mendo Mix" frost protectant spray developed by Stewart Bewley of Alder Springs who has been using copper sulfate and stylet oil to inhibit ice nucleating bacteria. It is pretty predictable when I do a trial whatever problem I am trying to study fails to show up!   Stewart has been working with this combination for about 16 years and has found that it can protect his vineyard fairly well down to about 28 degrees F. An application of 2% stylet oil and 3 lbs of copper in 100 gallons of water can treat about 5 acres of vineyard.  Typically, this will protect the vineyard for about 5 days from one treatment.

Working with the Mendocino Wine Company, we have established a trial on around 4 acres that is protected with copper sprays, copper plus stylet oil (Mendo Mix) and an untreated control. We also are using a split plot design in which half of the treatments have mowed cover crops, and the other half are disked so that there is no vegetation on the vineyard floor. So, 6 treatments, 3 replications, and we need to sample 30 leaves or shoots from each replication= 540 samples!  Dr. Steve Lindow at UC Berkeley is checking our samples to evaluate them for freezing low points and bacteria counts. This is the first trial that I am aware of that is really tracking the ecology of frost in vineyards based on following ice nucleating bacteria populations and their relationship to the vineyard floor.  We also have 12 microloggers in the plots to follow temperatures in the vine canopies thanks to fellow UCCE Farm Advisor Mark Battany.

So far the trial is unfunded, but we hope to apply to granting agencies next season to continue our work.  Special thanks to Al White and Tim Thornhill of the Mendocino Wine Company for cooperating on this important trial.