ABSTRACT
Risks to peach production from scab (caused by Cladosporium carpophilum) and plum curculio (Conotrachelus nenuphar), two key pests in the southeastern United States, are high until 2 months past petal fall and then decreases during midseason. This suggests that reduced-input pesticide strategies may effectively control both pests during the latter period. In this study, we evaluated midseason pesticide applications according to an alternate-row middle (ARM) spray program in which sprays were applied only to every other tree row while reducing tractor speed and keeping application intervals unchanged relative to conventional spraying of both sides of the trees. In a 2-year trial in a research orchard, conventional sprays of fungicide (primarily sulfur) and insecticide (primarily phosmet) were applied at 10- to 14-day intervals until first cover, followed by continued conventional sprays of fungicide and insecticide (standard), conventional sprays of one pesticide together with ARM sprays of the other pesticide, or combined ARM sprays of both pesticides. Schedules with midseason ARM sprays of both pesticides also were evaluated in two commercial orchards in 2 years. In all experiments, plots receiving combined ARM sprays were equivalent to the standard in fruit quality and control of scab and plum curculio. Combined ARM spraying resulted in lower environmental nontarget effects (as estimated by the Environmental Impact Quotient) and reduced application time by 25 to 33% for each midseason spray and 12.5 to 18.5% for the entire period from petal fall to the preharvest interval.
