Evaluation of environmentally friendly products for control of fungal diseases of grapes

Summary

Various environmentally friendly products were tested for efficacy in controlling powdery mildew, downy mildew, black rot, Phomopsis, and Botrytis bunch rot in grapes over several years. The products tested were: JMS stylet oil (paraffinic oil), Serenade (Bacillus subtilis), Croplife (citrus and coconut extract) + Plant food (foliar fertilizer), Armicarb (potassium bicarbonate), Elexa (chitosan), Milsana (giant knotweed extract), and AQ10 (Ampelomyces quisqua/is). JMS Stylet Oil, Armicarb, Serenade, AQ10, Elexa, and Milsana all provided moderate control of downy and powdery mildew. JMS Stylet Oil and Armicarb also reduced Phomopsis rachis infections. Armicarb looks especially promising for black rot control. Serenade and Croplife + Plantfood provided moderate to good control of Botrytis bunch rot, and moderate control of downy mildew and Phomopsis leaf spot. Milsana provided moderate control of Botrytis bunch rot. The tested products were often out-performed by standard or new products, especially under the humid conditions common in Michigan. However, some products appeared promising for certain diseases and merit further study, especially those that may be of interest to organic growers. Optimizing timing of these products may enhance their performance, since most of them are protectants and have little or no eradicant activity.