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JUNE 2005 It is Time to Remind Everyone of Sulfur Dust Stewardship LODI - WOODBRIDGE WINEGRAPE COMMISSION Sulfur dust is the backbone of Lodi’s powdery mildew management program. Now that the season is in full swing a lot of sulfur dust is being applied. I have become aware that some of the sulfur stewardship principles promoted in our region have not been adhered to in some instances. For example, during a recent early morning period of temperature inversion a sulfur dusting in a vineyard next to a county road created a dust cloud that slowly drifted across the road creating a hazard for passing vehicles. In other cases sulfur dusting was done in such strong winds that it • was clear the application would not provide effective coverage to control mildew. To preserve the use of sulfur in Lodi vineyards for the long term RESEARCH IPM NEWSLETTER it is absolutely critical that all growers and equipment operators adhere to the sulfur stewardship principles. I am sure none of us want to see the Lodi wine industry featured on the evening news because a school bus was dusted with sulfur. Some of the more important sulfur dust stewardship are: • Stop dusting activities if sulfur will drift into sensitive areas Managing Spider Mites in Lodi Vineyards • Avoid applications when people are active in areas bordering a treated vineyard responding from the warmer growing regions Willamette mites and Pacific mites are diffi- BY CLIFF OHMART reported that about the only time they see cult to tell apart. The UC Grape Pest • If dusting equipment allows, disengage blower when making row turns LWWC Research/IPM Director Willamette mites become a problem is when Management Manual may be of help here. An they occur in vineyards at very high numbers even better way may be to have your PCA • When possible sulfur dust at night or on weekends It is that time of year again, time to worry early in the season. In the Lodi region, it is show you the difference between them. It is clear from monitoring 70 vineyards over the important to tell them apart because during • Sulfur dust should not be applied when wind velocity exceeds 10 miles per hour about mites. I will be the first one to admit that I find dealing with mites in Lodi vine- last 8 years for the BIFS program that the hot weather Pacific mite populations can • Avoid dusting during dead calm conditions in the presence of an inversion layer; in these situations apply sulfur dust where there is a minimum yards a difficult issue. I have two main level of Willamette mite infestation that is increase much more rapidly than Willamette air movement of 2 miles per hour reasons: 1) It is very difficult to accurately considered unacceptable by growers and mite populations so you have less time to estimate their level of infestation because consultants can vary considerably. Part of this react to them and it is easier to get into • Leave adequate buffer zones to protect sensitive areas their distribution in the vineyard is often is explained by things such as different vari- trouble. Moreover, a really bad Pacific mite patchy; and 2) There is not a whole lot of data eties, different irrigation strategies, or infestation can burn leaves to a crisp whereas • Cover sulfur stewardship with all applicator employees to go on regarding treatment thresholds and differing canopy management styles. Willamette mites just make them look tired. impacts that mite damage have on winegrape However, it is also clear that some growers Record How Mite Levels Affect Yield Copies of the principles of sulfur dust stewardship are available in English and Spanish from Cliff or Chris at LWWC’s office. yield and quality. Furthermore, it seems that and consultants have more tolerance for and Quality: It is not very likely that detailed Pacific mite is becoming more common in the Willamette mite damage that others do. research by University scientists will be done Lodi region and this species behaves much So what can we do in Lodi to improve any time soon on affects of mites on wine- differently than Willamette mite so being able our mite management? Do more quantitative grape yield and quality. Therefore the only to tell them apart is very important in dealing monitoring, keep written records of this way we will improve our mite management in with them successfully. monitoring, identify the mite species you have Lodi is for growers to learn from their own The following discussion is a great illus- in your vineyards, make and record observa- on-farm experience with them. To do this tration of what comes from a lack of data on tions on how mite levels affect yield and effectively means not only keeping records of mites in winegrape vineyards. I recently quality, and take advantage of the experience mite levels but also yield and quality so you participated in an on-line discussion with of your PCA (if you work with one), your can make correlations between mite numbers several California pest control advisors about farm advisor (Paul Verdegaal) and other and yield and quality and adjust your mite whether Willamette mite is a pest or not. It growers by talking with them about their management accordingly. began with a pest management consultant views on mite management and getting their Take Advantage of Experience of PCAs, from the San Joaquin Valley reporting that he help in identifying the kind of mites you have Paul Verdegaal, and Other Growers: PCAs never recommends a treatment for Willamette in your vineyard. and your farm advisor, Paul Verdegaal, see mite unless a client insists. He stated that Quantitative Monitoring: Without many vineyards farmed in many different although in some vineyards Willamette mite measuring mite levels in some quantitative ways in the presence and absence of mites. feeding can make the vines look pretty way you have no way to relate their numbers They are in the best position to help you deal ragged, he never sees any affect on the fruit. to their effects on vine yield and quality. As with the many unknowns of mite manage- He then asked what other consultants do seasons go by, good quantitative monitoring ment. Moreover, PCAs have extensive experi- about Willamette mite-infested vineyards. He records, coupled with measurements of yield ence with the several new miticides have got several responses from around California. and quality will allow you to refine your mite come on the market the last few years, such as Some said they do not view the mite as a treatment thresholds. Probably the simplest Nexter, Fugimite, Acrimite, and Agrimek. problem while others said in certain situations way to measure mite levels is using what is Each material has strengths and weaknesses it can adversely affect winegrape quality if not known as ‘presence/absence’. Take a given that you should know about. Talking with LODI, CA 95242 CA LODI, treated. Some believe that in the cooler grape- number of leaves off several vines in one other growers may be extremely valuable 2545 W 2545 . TURNER RD. TURNER . growing regions of California’s North Coast part of the vineyard, ten is an easy because they see things from your in vineyards with poor soils and/or where number to deal with, and count the perspective and yet are dealing with deficit irrigation is pushing the vines to the number of leaves with mites on different vineyards than yours. limit in terms of crop to canopy ratio, a signif- them. Divide this number by the Lodi growers and PCAs are icant Willamette mite population (maybe total number of leaves and this fortunate because the region is 60% infestation or greater) can significantly gives you a percentage of leaves famous for the information that gets delay harvest and/or significantly lower the with mites on them. Write this shared within the winegrape ST OCKT ON, CA ON, Brix level at harvest. They believe the mites down! The Lodi Winegrowers community. The only way I see us PERMIT #269 add to these other stressful factors and Workbook has more detailed making strides in improving our mite AID P actually push the vineyard over the edge and suggestions for mite monitoring. management is to continue sharing U.S. POSTAGE U.S. quality suffers. Some of the people Identify the Mite Species: information on this important topic. PRSR T STD. RETURN SERVICE REQUESTED SERVICE RETURN L ODI-WOODBRIDGE WINEGRAPE COMMISSION • 209-367-4727 • F AX 209-367-0737 • www.lodiwine.com Calculating don’t seem to need as much applied nutrients BY PAUL S. VERDEGAAL as most other commodities. From budbreak GROWER PROFILE: Robert Abercrombie IN THE VINEYARD University of California until bloom time shoots are relying almost Herbicide Rates Cooperative Extension Farm Advisor entirely on stored reserves for nutrients, other than a minor contribution from photosyn- Can Be Tricky Although Robert Abercrombie Robert now firmly believes The 2005 season has become a challenge to Winged Sharp Shooter (GWSS) and Vine thesis of the new leaves. Potassium and zinc was born in Visalia, CA, he that soil fertility is one of the plan around the frequent rainstorms. After Mealy Bug (VMB) provide plenty of concern, deficiencies (boron in more recent years) have wasn’t born into a farming most important factors “in two years of below average soil moisture at but the economy and wine sales seem to been a problem, but too much nitrogen has A LODI PCA RECENTLY BROUGHT TO family like many of the rest of creating a healthier environ- bud break, there should be an abundance of improve.

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