Efficacy of fungicides for management of powdery mildew on Pinot Noir, 2014

摘要

Fungicide treatments were arranged in a randomized complete block design in a 'Pinot Noir' (on V. rupestris x V. riparia 101-14 rootstock) vineyard planted in 1998 on a 7 x 8 ft spacing. Pinot Noir vines were trained to a Guyot system and pruned on 10and 11 Mar. Each treatment was replicated on four sets of five vines. Treatments were applied approximately every 14 days using a hooded boom sprayer at 150 psi at a rate of 96 or 103 gal/A. According to the Gubler-Thomas powdery mildew forecasting model, there were seven rain events between bud break and the end of bloom that were favorable for ascospore release and infection: two severe infection periods (22 Apr and 8 May) and five moderate infection periods (21, 24 and 26 Apr, 3 and 18 May). The risk index varied from 0 to 60 during May but shot up past 60 in early Jun, remained high until Jul 12 when it dropped below 60 for a month during an usual hot period, then back above 60 on Aug 14 until the end of Sep. Incidence and severity of powdery mildew on leaves were evaluated on 30 Jul and 18 Aug and on clusters on 30 Jul and 15 Aug. Powdery mildew disease data were collected by randomly examining 50 leaves or clusters from the middle three vines of each replicate.