By Clint Thompson
Fruit rots are an annual concern for Georgia blueberry producers. But fungicide resistance is gaining traction as a worry for farmers moving forward.
Blueberry farmers have the fungicides needed to manage fruit rots every year. But they need to be mindful of not putting all their effort into one specific mode of action, explains Jonathan Oliver, University of Georgia (UGA) assistant professor and small fruits pathologist.
“Fungicide resistance has always been a concern. What we have found in recent years suggested it maybe should be a bigger concern,” Oliver said. “We don’t know for sure in a given field what the fungicide resistance situation is without looking, but looking at samples collected from multiple sites around the blueberry growing region of Georgia, we do see at least some isolates of some of these fruit rot pathogens that are resistant to some our very crucial fungicides.
“There aren’t really a huge amount of different types of fungicides that are available for blueberries so any time we could potentially lose one to resistance, it could really affect things long term. It really is important to be good stewards of that.”
Annual Blueberry Update
Oliver noted during the Annual Blueberry Update meeting in Alma, Georgia, last Wednesday that Alternaria isolates with resistance to Qol fungicides and boscalid, and Botrytis and Collectotrichum isolates with multiple fungicide resistances were identified in Georgia blueberries.
Growers need to rotate their fungicide chemistries to preserve what works in fighting off Anthracnose Rot, Alternaria Leaf Spot and Fruit Rot and Botrytis Flower Blight and Fruit Rot.
“Each fungicide has a mode of action. If you use fungicides with different modes of action, you’re less likely to select for a particular type of resistance. Rotating among those different modes of action or using things like multi-site fungicides like Captan, they may be less effective than some of these other fungicides on an individual basis, but over time they’re way less likely to lead to resistance development and it could help protect some of these other chemistries,” Oliver said.