DISEASE-MANAGEMENT COMPONENTS OF ADVANCED INTEGRATED PEST-MANAGEMENT IN APPLE ORCHARDS

Reducing fungicide use in commercial apple orchards is particularly pr oblematic, although success would positively effect other aspects of o rchard ecology, primarily arthropod management, and may alleviate ecol ogical and food-safety concerns. Methods for reducing fungicides were tested in the context of advanced integrated pest management (IPM), in which arthropod pests are managed with minimal use of pesticides foll owing the petal-fall stage of apple growth. The potential ascospore do se (PAD) method for predicting inoculum density of Venturia inaequalis , which causes apple scab, was used in conjunction with ascospore-matu rity evaluation and ergosterol-biosynthesis-inhibiting fungicides to m anage scab in advanced IPM blocks. In 78% of the cases studied, PAD in dicated growers should delay the first fungicide application, but grow ers actually followed this recommendation in only half of these cases. Where growers followed the recommendation, they applied significantly less fungicide, saving an average of over one application during the primary apple scab season, a 26% reduction, A combination of summer pr uning and limited captan use was recommended for management of flyspec k (caused by Schizothyrium pomi) and sooty blotch (caused by three ass ociated fungi). Growers generally followed the advanced IPM recommenda tions, and during the summer applied 34% less fungicide in the advance d IPM blocks. The program showed that growers could achieve significan t fungicide reductions in apples using these methods, although it also indicated that they were sometimes reticent to implement them. (C) 19 97 Elsevier Science B.V.