Issue link: http://winesandvines.uberflip.com/i/62516
GRAPE GRO WING counts were sprayed while some were not, and many vineyards with moderate counts were sprayed, while some with similar counts were not. In an ideal integrated pest management (IPM) world, this should not be the case; sprayed vineyards should have high counts, prompting the decision to spray. Unsprayed vineyards should have low leafhopper counts, meaning no spray is necessary. One of the biggest challenges of pest management is determining if perceived risk of pest damage matches real risk. Remember that the counts in the graph are the high counts for the year for each vineyard. One could make an argument that the counts in some of the unsprayed vineyards built up over the summer and that is why the counts were high but did not require treatment. However, the highest counts for the year in each vine- yard occurred from mid-May to mid-June, not toward the end of the growing season. After thinking about the data on the graph, I realized they pro- vided some great learning opportunities. First, the data indicated that the economic threshold used by growers and PCAs in the project varied tremendously, from a very low two nymphs per leaf to very high 45 nymphs. I do not know of any growers or PCAs who spray leafhop- pers just for the heck of it. They are very aware that spray- Perceived risk can be affected by factors such as how often vine- yards are monitored for pests. AVAILABILITIES CALL NOW FOR 2012 Award-winning quality… …a tradition for over 20 years…has made Vintage Nurseries the perfect pairing for growers desiring the finest, most reliable yields. Our state-of-the-art technology, industry-leading service and wide selection make Vintage Nurseries a California classic. Whether your needs include the finest field-grown dormants, potted green vines, rootstock rootings or own-rooted plants and cuttings, Vintage Nurseries assures you of the finest quality products…every time, for every wine. Place your order today, and capture classic quality from the leader in the field. 661-758-4777 Wasco 800-499-9019 Paso Robles 805-237-8914 209-523-8036 Modesto Santa Rosa 707-542-5510 www.VintageNurseries.com Serving the Wine, Table Grape and Raisin Industries Wines & Vines nOVeMBeR 2011 109