Fungicide control of grape powdery mildew, trial II and V, 2014

摘要

Registered and experimental fungicides were evaluated for control of powdery mildew in a 44 yr-old Chardonnay vineyard in the Sacramento-San Joaquin River delta region of California. This report presents data for trial II and V. Experimental plots consisted of two-vines arranged in a complete randomized design with 5 replicates per treatment. Fungicides were mixed in 25 and 50 gal Nifty-Fifty pump tank/engine systems (Rears Mfg. Co., 2140 Prairie Road, Eugene, OR 97402) and applied with hand-gun sprayers at 150-200 psi to run-off. Fungicide treatments were applied from 14 Apr until 11 Jul. Spray volumes were gradually increased from 100-250 gal/A as the vines grew, to ensure complete coverage and better air circulation. Leaves were removed on 21 Mayand 3 Jun on the north side and south side of the vines to provide better air circulation and fungicide coverage. Disease incidence and severity were assessed on 21 Jul. Twenty five random clusters in each plot were evaluated. Incidence was determined as the percentage of infected clusters per plot with at least one powdery mildew colony; severity represented the percentage of infected berries per sampled cluster, averaged across all clusters and across all plots.