By Clint Thompson
Mancozeb’s uncertain future as a fungicide option for grape growers means research must be done to find its eventual replacement(s).
Phil Brannen, UGA Cooperative Extension fruit disease specialist, discussed Mancozeb and what options are being studied.
“We’re looking at what can we do, if potentially, it was taken off market. What would we do to try to compensate where we have to? And one of the things that we’re looking at is just looking at minimal rates of Captan; you know, looking at the low rates and seeing if we can get by,” Brannen said. “That would at least allow us to expand the number of applications of Captan, which could take care of at least having something that’s a contact material with activity that is somewhat similar to Mancozeb in some respects. So that’s one thing.
“Then we’re also looking at copper, which we’ve never utilized much at all in the southeast. I mean, it is utilized in some places. It’s just generally not utilized because it can be toxic to the grape itself. It can cause damage to leaves. But we’re looking at it, you know, and saying how much damage does it cause? Is it something that we can incorporate? So far, it’s one of those things where you look at it and say, ‘Well, it does something, and it is better than nothing for sure, but it’s not as good as Mancozeb.”
Background
Mancozeb’s value is based on its effectiveness against certain diseases and its lack of developing resistance. However, it is under review by the Environmental Protection Agency (EPA), though it may be another couple of years before the EPA makes a decision regarding the chemical’s future. It may not be available at all or available with certain restrictions. That emphasizes the importance of research being conducted at UGA.
“You know, people continue to tout biologicals as potential replacements. The EPA talks about that, and they’ve mentioned that in some of their documents. But like the biological we tested last year, we didn’t see any activity at all,” Brannen said. “We do have some good active materials that are systemic materials, but they develop resistance. And if we put too much pressure on those, use them too much, then we’re going to have a lot of resistance, and that’s the problem.
“If we have to replace (Mancozeb) with more expensive fungicides and they’re going to develop resistance, that’s going to add to the pressure we have on the market. It’s not something that we’re looking at and taking lightly, I’ll put it that way.”