Now that spotted wing drosophila is here to stay, berry growers in NY need radically different plans to grow a healthy crop. Marvin Pritts, Professor and Chair, Department of Horticulture, Cornell University, shares strategies for berry growers in his recent article, published in the NY Berry News, Horticultural Strategies for Living with SWD. Details on pruning, trellising, and sanitation to encourage open canopies and early fruiting are a "must-read" for growers developing plans for next year's battle with SWD.
In September, SWD populations in Suffolk County increased over four-fold, with more than 400 per trap (up from <100). Similar trends have been observed in other regions. Late season raspberries are almost 100% infested in blocks without insecticidal control. Since early August, Faruque Zaman, Suffolk County Cornell Cooperative Extension entomologist, has been checking grapes for SWD infestations, looking for SWD eggs’ white breathing tubes extending from within the intact grape. During early September, SWD was detected in <1% of Merlot and Pinot Noir berries. However, on Sept. 27, a Merlot sample (150 berries) showed 25% of berries with SWD oviposition, whereas, no SWD was detected in Chardonnay from the same vineyard. The absence of other preferred hosts at this time of the season might be a factor in the sudden upswing in SWD infestations in grapes. Monitoring will continue through fall, but Cornell University entomologists still maintain that SWD poses a low threat to grapes on Long Island and in other regions of New York State. Decisions to treat grapes should be based on scouting for fruit infestation, projected harvest dates, and the potential for rain which can lead to fruit rots in infested clusters.