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W i n e s & V i n e s s e p t e m b e r 2 0 1 4 79 WineEast tant rootstocks are also being tested. Test plots of different selections have also been es- tablished in Temecula, Texas and Alabama. Control of Pd in texas In the past 15 years, the wine industry in Texas has increased dramatically—especially in the Texas Hill Country west of Austin, an area long consid- ered to be a transition zone between the hot zone for PD and a lower probability of the disease being present. Today, Texas has 204 wineries; the Hill Country region includes 42 wineries, and many of them are growing vinifera vines. How are they succeeding when PD is a problem that probably will not go away? First of all, researchers in the state now recognize that PD is cyclical: Cold winters or drought can kill back both the bacteria causing the disease and the vectors that carry the causal agent from a host plant to a susceptible vine, which in turn causes the dis- ease pressure to lessen. The cyclical nature of the problem gives growers hope that they can address the source of the pathogen—the bacteria and the vectors that are responsible for the infection—even though there is no known control for the disease. Selection of a vineyard site with low disease risk is an important initial step. Native plants such as wild grapevines that may harbor the bacte- ria can be removed from the vineyard area, and susceptible varieties can be planted away from grapevines that are toler- ant to Xylella fastidiosa. Growers are learning to rec- ognize signs of the disease, confirm the symptoms by laboratory diagnosis and then immediately pull out infected vines to prevent spread of the bacteria from vine to vine within the vineyard. Timely application of spray materials to control sharpshoot- ers is also beneficial. In Califor- nia, parasitic wasps have been used as a biological control of the sharpshooter population. Imidacloprid is one pesticide that does kill sharpshooters, but it may also impact parasitic wasps as well as the sharpshoot- ers. It also has been cited as a possible cause of bee decline and colony collapse disorder. According to Dr. David N. Appel, professor of plant pa- thology and Texas A&M AgriLife Extension specialist, climatic factors also affect the sharp- shooter population in PD-prone vineyards. Texas experienced a severe drought in 2011, which reduced the number of sharp- shooters, and the cold tempera- tures during this past winter may also impact the insect population. Kamas agreed that weather is a big component in controlling the presence of sharpshooters, but he also noted that it was vital to make the vineyard a "sharpshooter inhospitable place." WE EASTERN WINE LABS Serving the Analytical needs of East Coast Wineries WWW.EASTERNWINELABS.COM Ph 609-859-4302 Cell 609-668-2854 chemist@easternwinelabs.com AOAC Member EasternWineLab_Mar09.qxp 1/22/09 9:47 AM Page 1 Excellent for spraying: VINEYARDS, vegetables, orchards, nurseries, Christmas trees, mosquitoes, cattle, chicken houses, etc. Low Maintenance High Performance Motor Models available S a l es C om pa n y – Mist Sprayers – References available in your area American Made We offer a complete line of low volume mist blowers. For free brochure contact: Swihart Sales Co. 7240 County Road AA, Quinter, KS 67752 785-754-3513 or 800-864-4595 www.swihart-sales.com The cyclical nature of the problem gives growers hope that they can address the source of the pathogen, the bacteria and the vectors that are responsible for the infection.