Evaluation of fungicides for the control of Botrytis bunch rot of grape, 2014

摘要

The trial was conducted in a vineyard with mature Riesling grapevines trained to bilateral cordons on a vertical shoot-positioned trellis system located northwest of Soledad in the Salinas Valley of California. The experimental design was a randomizedcomplete block consisting of ten treatments. Each treatment was replicated four times using four-vine plots. Applications were made on 7 May at full bloom, 4 Jun at cluster pre-closure, and 23 Jul at veraison (12.0 Brix). Fungicide applications were made in a volume of 100 gal/A of water at 250 psi using a Rears Nifty gas powered sprayer with a single hollow-cone nozzle handgun sprayer. The surfactants Dyne-Amic and Kinetic were added to the treatments on a 0.125% and 0.5% v:v basis, respectively. Kinetic is approved for organic production (www.omri.org/omri-lists) and was added to the biofungicides to maintain organic farming acceptance. Cluster evaluations for Botrytis bunch rot incidence and severity were done on 3 Oct when the fruit was at 20.4 Brix. Evaluations were made by visually examining 50 interior clusters per replication. Incidence was measured as the percent of clusters with Botrytis-infected berries. Severity was determined by estimating the percent of berries per cluster that were infected with rot.