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The diamide class of insecticides is "probably the most incredible chemistry my colleagues and I have ever seen on caterpillar pests," says Angus Catchot, Mississippi State University Extension professor of entomology. "It's very selective, but very, very efficacious."
AMONG THOSE attending the annual meeting of the Mississippi Agricultural Consultants Association were, from left, Allen McKnight, Delta Agri-Consulting, Greenville, Miss.; Jack Clayton, FMC, Tunica, Miss.; Gill Corban, Jimmy Sanders, Inc., Cleveland, Miss.; and Jay Turner, Brandt Co., Southaven, Miss.
Going into the 2014 season, growers will have access to an “exciting” class of insecticides, says Angus Catchot, Mississippi State University Extension professor of entomology. "The diamides (Prevathon/Belt/Besiege) are “probably the most incredible chemistry my colleagues and I have ever seen on caterpillar pests. This chemistry is very selective, but very, very efficacious.”
And he said at the annual meeting of the Mississippi Agricultural Consultants Association, “It lasts a long, long time, with as much as 90 percent control after 32 days in bioassays— which is fantastic for growers and consultants. But from our standpoint, we have concern about the potential for development of resistance.”
Andrew Adams, a Ph.D. student, has been working on developing a baseline susceptibility model for the diamides, Catchot says. “This would provide us benchmark to compare back to in the event we start seeing control problems in the future.”
Some of the products in this class are known to be systemic when taken up through the roots, he notes. “We haven’t known whether it would move into the plant from foliar applications. We didn’t think it would, but we were curious to find out.
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“We made a foliar application of 10 gallons per acre with hollow cone nozzles, just as we’d spray any other test. Soybeans were at about R-3. Then we watered them, waited, and pulled samples from the newest trifoliate that we knew positively hadn’t been treated.
“We conducted bioassays with corn earworm larvae and we found that, yes, there is apparently some systemic activity with foliar applications. Eleven days after treatment we were getting fantastic control systemically with Prevathon. We weren’t seeing that with Belt, which is in the same class of chemistry, but acts a bit differently.
“We repeated the test at 18 days and 25 days, and with Prevathon we were still seeing 90 percent control on new growth. That was pretty amazing. Even at 32 days, we were seeing 90 percent control.
“At 25 and 32 days, we did a residual check on leaves lower in the canopy that we knew had been sprayed. We bioassayed those tissues and all the diamide compounds, including Belt, were showing fantastic residual after 25 days.”
“I wouldn’t necessarily say because Prevathon is moving systemically that it will help with bollworm control. DuPont doesn’t think it will move into the fruiting structures, which is where bollworms feed.