Wines & Vines

April 2014 Oak Alternatives Issue

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60 p r a c t i c a l w i n e r y & v i n e ya r d a p r i l 2 0 1 4 g r a p e g r o w i n g SHuR FARMS ® Frost Protection Award Winning Technology! Internationally Acclaimed! Shur Farms Frost Protection 1890 N. 8th St., Colton, CA 92324 Toll Free (877) 842-9688 info@shurfarms.com ~ www.shurfarms.com Cold Air Drain ® Powerful Cost Effective Versatile Convenient Manufacturer of the world's most advanced frost protection Need a Better Cork Supplier? All Natural Cork Closures Fresh Corks Directly From Portugal 4th Genera on Family Cork Producer Free Branding Free Shipping Free iS Better Ask about our Progressive Discounts Experience the Slimcork® Advantage CALL TODAY phone (203) 681-7743 Cell (860) 335-0667 email: reliablecork@gmail.com • www.reliablecorksolu ons.com ing a seven-year period without increas- ing disease development. Spore trapping in California Beginning in 2011, both Doug Gubler's group (University California, Davis) and Set h Sc hwebs (Coastal Vit icu lt u ral Consultants) began examining the utility of spore trapping in various California grapegrowing regions. Schwebs began exploring how to commercially imple- ment this technology. Weekly trap sample collection occurred during normal vine- yard visits for monitoring soil moisture and vine stress. This approach signifi- cantly reduced the labor and travel needed for sample recovery and made the sampling economically feasible. In 2013, as in 2011-12, there was a high degree of variability among vineyards in the amount of powdery mildew inocu- lum detected (Figures 1 and 2), which suggested two different approaches to managing the epidemic. Some vineyards were able to reduce the number fungicide applications. For example, the vineyard in Figure 1 was treated with one early spray (about 3 -4 inches of shoot growth) containing 1% mineral oil but not again until late May due to spore trap data, which resulted in one less fungicide application than the five they typically applied. The second approach was to alter the fungicide program. Based on the spore- trapping data, Coastal Viticultural Con- sultants made suggestions to either change the timing or type of fungicide used at specific times in the season. Photo BY WAlt mAhAffee Figure 1: A spore-trapping report from Coastal Viticultural Consultants for a Napa Valley Cabernet Sauvignon vineyard. The blue line is daily high temperature, and the red line is daily Gubler- Thomas index on the left y-axis. Green bars indicate no powdery mildew detection, and yellow bars indicate powdery mildew detection and concentration on the right y-axis. Figure 1: Napa Cabernet Vineyard 2013 Powdery Mildew Spore Trap Report Temperature (F)/Mildew Index GPM Spore Count Prepared by Coastal Viticultural Consultants Inc. Weather Data Source: Carneros CIMIS 120 100 80 60 40 20 0 1M 100k 10k 1k 100 10 1 Powdery mildew infection of the inflorescence can cause caps to remain on flowers, prevent- ing fertilization and increasing the chance of Botrytis bunch rot. — High Temp — Powdery Mildew Index ■ Positive GPM ■ No GPM Detected

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