Evaluation of LEM17 for control of early-season apple diseases, 2008.

摘要

Treatments involving LEM17 (penthiopyrad) applied alone or in combinations with other fungicides were evaluated in an orchard established in 1991. The orchard contained two-tree plots of 'Jerseymac' and 'Ginger Gold' on M.9 rootstocks.Trees within plots were spaced 8.5 ft apart, with 17 ft separating trees in adjacent in-row plots and 20 ft between rows. Plots within rows were separated by large cedar trees that provided inoculum for rust diseases and limited spray drift betweenplots. All treatments were replicated four times. Treatments were applied by spraying trees to drip using a high-pressure sprayer and a handgun at 200 psi. Treatments were applied on 8, 17, 25 Apr; 3, 11, 22, and 30 May. For treatments 4 and 5,LEM17 was applied on 8 and 25 Apr and 11 and 30 May with Manzate 1 lb/100 gal being applied in both of these treatments on the other spray dates. Captan 80WDG 30 oz/A was applied to the entire block, including control plots, on 13 Jun using anairblast sprayer. Flint 50WG 2 oz/A was similarly applied to the entire block on 25 Jun. No other fungicides were applied thereafter. Jerseymac bud stages were 7 Apr - green tip, 17 Apr – half-inch green, 22 Apr - tight cluster, 25 April - pink, 2May – full bloom, 11 May - petal fall. The first apple scab infection period occurred 28-29 Apr (33 hr, 48 deg F), with additional infection periods 1-4 May (41 hr, 49 deg F), 9-10 May (28 hr, 49 deg F), 15-17 May (34 hr, 51 deg F), 21-22 May (21 hr, 51