Wheat production in the upper Southeast benefits from a stable of reliable fungicide products and research at the Eastern Virginia Agriculture Research and Extension Center (EVAREC) indicates both new and old wheat fungicides still work well.
Virginia Tech Plant Pathologist Erik Stromberg, speaking at a recent field day at the EVAREC, noted that Kocide, an old copper-based fungicide, provided excellent disease control in 2008 tests. It remains to be seen, he notes, whether the intense greening effect of the Kocide treatments significantly affects yields.
All the 17 treatments in the wheat disease control tests, performed well at various application rates, Stromberg says.
Triazole products, which have some eradicative activity and are systemic, worked well alone, or with other families of products. Strobilurin-based fungicides, which have primarily protectant activity, and some systemic activity, also worked well.
Tilt, at low rates (2 ounces per acre) at green-up time or Growth Stage 30, followed by Quilt at heading compared favorably with Quilt alone. Quilt is a combination of Tilt and Quadris, which was applied at late flowering. Both applications worked well, according to Stromberg, though he notes he prefers the full four ounce treatment of Tilt.
Headline, another popular strobilurin fungicide worked well at six ounces per acre. Both at flag leaf emergence or a single application at head emergence also worked well, the Virginia Tech pathologist says.
Over the years, he says, the combination of 4.5 ounces of Headline at flag leaf emergence, followed by another 4.5 ounces at head emergence. “Based on the success of this combination, I tried the same kind of split application with other fungicides,” he adds.
Stratego, a strobulurin plus a triazole (Tilt) was applied at 10 ounces at flag leaf and worked well as did the same rate of the fungicide applied at heading. Though these applications worked well, there are some advantages to splitting the 10 ounce application.
“The advantage of splitting the application allows you to put on the material early, then wait and see whether disease pressure builds up. If you get no disease pressure, you save money. If you get disease pressure, you can still control it with the late application, Stromberg explains.
The same one-time application versus split application was done with Quadris, a strobilurin. Again, it worked well in both scenarios.
With Tilt, he used only a single application at either flag leaf or heading. Again, Tilt appeared to work well in the tests.
Stromberg notes the good news is that growers have several options of products and how these products are used.
“All of these fungicides have excellent control of the target disease organism, if you can get the material on the plant, where it needs to be and keep it there long enough. Trying to get an effective dose of a fungicide on a vertical surface prior to a rain event and allow it to stay there for 10 days is a tough thing to do,” Stromberg says.
A wheat plant flowers over a period of 7-10 days, or about a third of the plant at a time flowers. Entry point for most fungi is at the spent anther cases where the wheat plant flowers. This is the critical period for wheat disease control, he explains.
Stromberg says he uses a spray boom with 8001GS tips that are offset by 30 degrees. The idea, he says, is to get front and back application of the material on the wheat plant.
Using fluorescent dyes, he has measured the effectiveness of his spray boom. Results indicate this type spray setup works better than a single flat fan nozzle. “It’s better, but not perfect for getting the right dose on the plant heads.”
Controlling fusarium head blight has been an ongoing challenge for upper Southeast wheat growers over the past few years. Stromberg says Karambe, a new fungicide recently labeled for wheat, has done a good job in statewide testing. However, he says the best way to control fusarium head blight in wheat is to not plant into corn stubble.
With no-till wheat gaining in popularity in Virginia and other parts of the Southeast, disease control and cost-efficient and soil-building tillage free systems seem to clash.
The inoculum for a number of corn diseases comes from decaying corn stubble.
Planting glyphosate tolerant corn varieties, which don’t break down as quickly as conventional hybrid stalks may be one way to overcome increased head blight problems in no-till wheat.
ProLine plus Folicur has performed well for fusarium head blight control. Stromberg says he never sought a federal label for Folicur, because he never felt it was better on head blight control.
BASF 556 is a combination of Headline and Karamba, another combination of strobilurin and triazole chemistry. The experimental material performed well in the EVAREC tests and offers a potential new weapon for wheat growers.
“Not every fungicide is perfect for every condition. Hopefully, by testing over a number of years, we can look at a set of conditions and make some observations as to which material or group of materials may be best under a set group of growing conditions,” Stromberg says.
“Each of these fungicides has a particular niche in which it works extremely well and others in which it isn’t so dramatic. Hopefully, by working with these products early in their development, we will be in a position to help growers make the best management decisions possible when choosing a fungicide,” he adds.
“Even with light disease pressure, under some circumstances, some of these fungicides seem to increase yields. In several locations around the state, including at the EVAREC, 2008 was a low disease pressure year. Hopefully, we can make some valid observations about the yield-enhancing capabilities of some of these fungicides,” Stromberg says.
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