Welcome and Announcements

You can subscribe to DPR’s online bulletin. Current topics include “Reviewing pyrethroid data”, “VOC regulations”, and “Green chemistry symposium”. Visit www.cdpr.gov/docs/listserv/listdesc.htm Focus Points Water Conservation – Mark Greenspan is a viticulturist and irrigation specialist whose company, Advanced Viticulture, is consulting with the Sonoma County Water Agency (SCWA) to help meet the 15% mandatory water use reduction from July 1st through October 28th, imposed by the State Water Quality Control Board. Water from Lake Mendocino that normally contributes to maintaining the Russian River summer flow is in short supply this year. Users of Russian River basin water will therefore be required to reduce use this year. Mark spoke to us about water conservation and the following is an outline of his presentation. Please also see the March/April ‘05 and May/June ‘05 issues of Practical Winery and Vineyard or visit the www.sonomawinegrape.org website for more details. I. Avoiding irrigation a. Keep vines small by starting irrigation later – Smaller vines use less water. Mark referred to them as “more thrifty vines”. This means not encouraging growth by starting irrigating too early, but letting your vines’ growth slow down before initiating irrigation. A quick shot of water during a heat spell is OK, as is a little water for fertigation. The idea is to have shoots slowing and stopping around set. Ideally you hedge 1 time after vine growth slows. b. Cover crops compete for water – This year, manage cover crops to reduce water competition. There is not a big difference between disking and close mowing.

II. Irrigation reduction a. Drip frequency and timing – More efficient with short, frequent irrigation sets. Better efficiency can translate into less water use, e.g. 8 hrs 1 time per week vs. 2 hrs 3 times per week (These numbers are for illustrative purposes only and do not represent actual recommendations.) b. Overhead irrigation to cool fruit during heat spells wastes water. Try leaving laterals and some leaves above the fruit zone to shade fruit. c. Irrigating at night or very early morning reduces evaporative loss. d. Deficit irrigation (minimal irrigation input)

i. Use shoot tips to determine when to begin irrigation. After tip growth stops, visual vine water status indicators are too gross, only indicating when too much stress is occurring (e.g. basal leaf loss, leaves avoiding sun). ii. Measuring vine water status after cessation of growth. 1. Pressure bomb. Measures leaf water potential (leaf suction) – how much energy the leaf is using to extract water from soil. 2. Porometer. Tells how the vine is responding to water stress by measuring how open the stomates are. Mark prefers this measurement and uses a device from Decason (www.decagon.com/irrigation/porometer, or contact Mark at mark@advancedvit.com). Less expensive than a pressure bomb, these handheld units are quick and easy to use. Mark sees differences with the porometer that are not apparent with a pressure bomb. 3. Leaf feel. A hands-on art/skill that one can develop by feeling exposed leaves and determining if they are warm (stomates closed: vine conserving water) or cool (stomates open: vine has easy access to water). iii. Use of instruments to measure soil moisture. Qualitative measurements that define how irrigations are working, how deep they are going.

1. Neutron probe. Most accurate.
2. Gypsum block, dielectric sensors. Relatively inexpensive and straightforward; continuous measurements for pattern identification. Mark noted that a recent article in the SF Chronicle on Dry Farming was perhaps not entirely applicable to our viticulture, in that it compared European dry farming, where there is summer rainfall. Grape Leafhopper - In general, no real issues yet. Despite early signs of potentially high populations from overwintered adults earlier this season, nymph populations have not reached threshold levels in most ranches. Some growers have been using the model leaf damage available in the IPM Fieldbook to judge canopy damage. The IPM Fieldbook can be purchased for $15 from the Sonoma County Winegrape Commission. Powdery Mildew – A few infected berries and laterals have been found. The heat spell should not deter anyone from applying their normally scheduled fungicide applications unless the canopy is limited, sulfur or oil are being applied, and your site may see temperatures over 95 degrees. Some minor phytotoxicity may occur, but it is generally insignificant in relation to stretching an interval when mildew pressure is high. A general rule of thumb to follow is to stop spraying when temperature reaches 80 degrees.

Canopy Management – Post set is the time to open the canopies around the clusters to reduce botrytis and powdery mildew pressures. Weeds – Mare’s tail germinates late and, as usual, escaped many of the last spring herbicide treatments. Roundup does control it under the vines. If it’s coming up in your cover crop, wait until just before it blooms to mow or it will develop short laterals with enough energy to set seed. Morning glory (field bindweed) is starting to bloom, and so now is a good time to control this one. Heads up · Light Brown Apple Moth (LBAM) – No finds in Sonoma, Lake or Mendocino. No further finds in Napa. General

· More PD? – Scott Quilty hosted our Russian River meeting as Dennis was out. Scott noted that a handful of new Pierce’s disease vines had been found at the Laguna Ranch. Also, they were using a leaf blowing machine for leaf removal and liking the results. Finally, they’ve had 2 county inspections this year, one a labor check on FLC compliance and the other a pesticide use inspection. · More leaf blowing – Richard Rued also uses a blower, an Aviador, designed by an airline pilot. There was an interesting question as to whether an ozone generator used to sterilize barrels might be adapted to work on hand washing mildew from infected clusters… Monitoring Points Vine and Grape Mealybugs – Crawlers are moving up, Argentine ants are getting busy, and ant bait stations seem to be working. Keep your eye out for ants on the vine. Find out where they are going to determine the source of their interest – scale, mealybugs, or sometimes during hot weather they just “highway” along the cordons because it’s cooler. If you see mealybugs, remember to watch for the destroyer predator that looks like a mealybug, but has the white waxy filaments all over, coming off its back and sides, whereas a mealybug just has the filaments coming from its sides in a neat fringe. It is time to start trapping for VMB. Traps and lures can be purchased at your local materials supplier. The traps attract males which are about the size of thrips. Mites – Pick 5 to 10 random leaves through a block representing upper, middle and lower canopy. Determine if the mites are Pacific or Willamette by the color of the front legs (Pacifics tan, Willamettes pale). Note presence or absence of mites on each leaf. Note the percentage of leaves with mites present. This is known as “presence/absence” sampling and correlates with the overall population of mites. Do the same for predatory mites and 6-spotted thrips (see UC IPM online for descriptions and pictures of these predators). If the ratio of predators to Pacific mites is 1:5, the predators will be helping to keep the mites in check. If the ratio is 1:4 or better, the Pacific mite populations will likely decrease. Willamette mites seem to need 25% presence of predators to stay in check, and will likely decrease with 30% or better presence of predators.

Predatory mite releases have been successful for Paul Kaselonis and Rafael Jiminez in blocks chronically infested with mites. The common theme is early releases over several years, and a noticeable reduction of chronic mite issues after 3 to 4 seasons of releases. Danitol, a third generation pyrethroid, is effective not only against a wide variety of insects, but also has efficacy against Willamette mites. The pyrethrins and earlier generation pyrethroids often cause mites to flare up when used for an insecticide application. Dennis Devitt, our host at the Russian River meeting, and Armon Azevedo from Wilbur-Ellis are conducting a large miticide trial in the Two Rocks area this year. It includes organic options, too, such as a micro-encapsulated soap. Sandy Henson treated for mites and had left a few control rows to judge the effectiveness of the material. Beneficials moved in to the control rows and took care of the mites. Leaving control rows can help you learn more about the dynamics of how your vineyard responds to pests and treatments. What is it? Necrotic spots and lesions on a syrah shoot brought in last month by John Kiger seem to be spreading up the shoot. Rhonda is collecting samples for lab analysis. Adjourn - Thanks for coming!