Efficacy of biopesticides has been examined through replicated experiments conducted under field conditions at the Cornell University research facility on Long Island. Most treatments consisted of products approved for or in development for organic production tested individually. Some treatments were combinations of biopesticides or a biopesticide and copper. Some experiments included a treatment with an organic copper or sulfur fungicide for comparison. A conventional fungicide treatment often has been included as a measure of maximum achievable control under the experiment conditions.
Conventional fungicide programs with biopesticides have been tested in recent experiments responding to non-organic grower interest in how to incorporate biopesticides into their fungicide programs. Options include applying biopesticides 1) preventively until symptoms are found then shifting to conventional targeted fungicides, 2) tank-mixed with targeted fungicides in place of conventional contact fungicides (chlorothalonil, copper, sulfur) for pathogen resistance management and 3) in place of conventional fungicides for the last applications to a crop. Programs have also been evaluated with biopesticides applied in alternation with targeted fungicides. A concern with this approach is impact on resistance management when the disease becomes more severe than when targeted fungicides are applied every application, which can occur because biopesticides are not as effective as targeted fungicides in the absence of resistant pathogen isolates. Maintaining a high level of control is a recommended component of a pathogen resistance management program to minimize selection pressure for resistant isolates.
Evaluations of Biopesticides and other Organic Fungicides
- Powdery mildew in cucurbit crops
- Downy mildew in cucurbit crops
- Phytophthora blight
- Foliar diseases of tomato
- Downy mildew in basil