Evaluation of Fungicide Spray Reduction Programs for Cold-Climate Grape Production in Wisconsin

Grape is the most widely planted fruit crop worldwide. Disease management is a crucial component for production in all regions where grapes are grown. However, there are some differences in pathogenic causal agents from region to region as well as differences in climate of the region and susceptibility of the grape cultivars being grown. There is often overlap in disease management strategies from region to region; with most management practices taken from production regions growing strictly V. vinifera. This leads to management practices likely optimized for more temperate regions being implemented in more continental climate regions where cold-climate hybrids are grown. This results in frequent fungicide sprays of cold-climate grape varieties despite their low susceptibility to many diseases. The goals of the proposed research are to evaluate the impacts of reduced fungicide spray programs on disease-resistant cold-climate grapes by 1) assessing reduced input spray programs compared to conventional calendar-based spray programs, and 2) assessing organic spray programs compared to conventional fungicide spray programs. For each objective, field trials will be established in research station vineyards, sprayed according to treatment plan, and rated all season long for fungal grape disease incidence and severity. Additional in vitro studies will evaluate organic-approved fungicides against several fungal pathogens to confirm antagonistic activity. The outcomes of this work will be the optimization of a spray program for fungal disease management in cold-climate grape varieties and reduced spray applications required to manage diseases.