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GRAP e GR o WI n G yards that have had particularly difficult mildew control issues during the previous season. Normally, growers apply lime sul- fur earlier as dormant sprays applied at higher rates to provide a general clean up for mildew, overwintering pests and even some of the wood-rotting fungi that cause measles, bot canker and other infections. Some growers in smaller vineyards actu- ally apply the spray with a hand gun only to the trunks and cordons, and instead of having to apply fairly high rates of lime sulfur (in the 10-20 gallons per acre range) applied with a fan sprayer, they get by very effectively with about 2 or 3 gallons per acre. At lower rates post-bud break, lime sulfur is also quite effective for stopping phomopsis blight on new shoots. Finally, lime sulfur probably also has some effect on bud mites and thrips, which may cause problems in some vineyards, especially during cool spring weather. Although lime sulfur is approved for or- ganic and biodynamic certified vineyards, it is still a Category 1 material in Cali- fornia. It requires a closed mixing system, primarily because the concentrated mate- rial is quite caustic (it has a pH of 12). It also smells a bit like sewage, so I wouldn't recommend its use near neighboring resi- dences or schools. Regardless, it is highly effective for controlling fungal diseases and mites. April is a good time to "plow down" cover crops before the soil gets too dry. Stylet oil is also a very good way to clean up any early infections of mildew, and it can also be toxic to mites, including beneficial predatory mites. Many growers start with wettable sulfur, which is less toxic to beneficial mites, then switch to stylet oil while the canopy is still relative- ly small, and switch to sulfur dust after bloom. Sulfur dust is tough on preda- cious mites, so it is advisable to limit its use early in the season, when Willamette mite numbers can build quickly if preda- tors are inhibited. Cover crops and the vineyard floor Vineyard floor management needs atten- tion in the springtime. If we are having dry weather, and you are growing "plow down" cover crops, April is a good time to incorporate them before the soil gets C M Y CM MY CY CMY K too dry. Bacteria and fungi in the soil re- quire moisture to decompose the grasses and legumes in most plow down mixes. Also, tillage and incorporation is going to be easier the more moisture there is in the soil. I highly recommend mowing before incorporation to chop the cover crop up. The more surface area of the cover crop that comes into contact with the soil, the quicker the material decomposes. The ideal time for incorporation is when The effects of small sulfur applications early in the season are visible later on. Ad Art2011AFINAL2.pdf 2/1/11 1:55:51 PM the cover crops are blooming. The carbon/ nitrogen ratios are generally below 20/1, and biological degradation happens quick- JMS Stylet-Oil® - The • Powdery Mildew? • Mites? Choice For Powdery Mildew and Mite control, grape growers have a choice: JMS Stylet-Oil JMS offers grape growers an effective alternative to early-season sulfur treatment. • Outperforms sulfur as an eradicant on powdery mildew - University researched and rated 10/10. • JMS Stylet-Oil is a stand-alone product for powdery mildew. • Eliminates early season inoculum growth that can cause late-season epidemics. • Unlike sulfur, JMS Stylet-Oil works well in cool weather, protects around the clock, and harmlessly degrades without potential air pollution. Apply this clean white oil early for mite control throughout the season. JMS Stylet-Oil is now available in its conven- tional formulation or an organic formula- tion that is OMRI listed for use in an organic program. Contact JMS for complete information and product data. Headquarters 4423 5th Place SW Vero Beach, FL 32968 Office: (772) 562-8770 Fax: (772) 562-7202 styletoil@aol.com www.stylet-oil.com Pacific Northwest Region 73585 Williams Lane Pendleton, OR 97801 Office: (541) 276-8566 Fax: (541) 276-6245 styletoil@eoni.com Wines & Vines APRiL 2011 61 NAOTAKE MURAYAMA