New soft pesticide treatments show promise through grant-funded study

When it comes to protecting a harvest, Andy Fles believes soft pesticide treatments have a place in the vineyard.

 

“Whether you use a fully-organic program or not, soft pesticides are effective,” said Fles, vineyard and facilities manager at Shady Lane Cellars. “You don’t have to be 100 percent organic to do this. You can replace some pesticides with soft treatments that are beneficial for insects and humans. 

 

“It’s about raising the floor for all of the growers.”

 

Fles has been studying the impact of standard pesticide treatments compared to more natural alternatives - new soft pesticide treatments - at Shady Lane Cellars since April 2024. With support from a national farming grant from the Sustainable Agriculture Research and Education, or SARE, he found limited differences between the two pest management programs. 

 

The SARE grant provided more than $11,000 in research funding for the last growing season and enabled Fles to conduct trials on about 12 acres of the property. He worked with Dr. Rufus Isaacs and PhD candidate Rehka Bhandari, grape team researchers on campus at Michigan State University, to test the efficacy of these products in their labs at Michigan State University. Winegrape Educator Esmaeil Nasrollahiazar, with MSU Extension, collaborated on this project.

 

The group has been testing new and more sustainable ways to manage powdery mildew and Botrytis bunch rot - two common diseases caused by fungus and bacteria that impact grapes grown across the country. 

 

The treatments he used included ProBlad Verde, ThymeGuard and Orange oil, among others. That means, at any time, the vineyard might take on the scent of a fresh Greek salad, a spicy cinnamon candy or a citrus breeze. 

 

Fles tested these treatments on roughly two acres each of Riesling, Vignole and Pinot Noir, while using standard treatments on another two acres for each varietal. 

 

“We chose these because they are the ones that present a lot of botrytis, sour rot,” he said.

 

For the soft treatments, Fles noted there was no economic impact, no defoliation. The percentage of infection was close for both types of treatment. However, Vignole, which is particularly susceptible to cluster rot, showed a difference of 5 to 10 percent fewer infected clusters using soft pesticides.

 

He said the soft pesticides did deter mites and aphids without impacting beneficial insects. The study showed that ProBlad Verde performed very well against botrytis and powdery mildew, he said.

 

Still, the weather itself was a factor throughout the year of study. 

 

The first half of the year was challenging as the season was wetter than usual – contributing to more spores that can cause bunch rot and powdery mildew to thrive in the vineyard. By fall, the vineyard was experiencing draught conditions. That made controlling bunch rot easier than usual. 

 

Fles expressed his appreciation to North Central SARE for the funding to make this project possible. Keeping in mind the goal of maintaining a more natural environment, he found the new products useful. He said that their findings show that soft pesticide treatments are also suitable for use at locations with a similar climate to Michigan – from New York to Pennsylvania, Ohio to Wisconsin.  

 

“We’ll take into consideration implementing ProBlad, and Cinnerate is on order,” he said.