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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.
Coverage is important
“So at the end of the day, coverage is still very important to provide adequate residual control. It is also important to note that, when these materials are normally applied, most of the vegetative growth of soybeans is over, so practically we are trying to figure out what this may mean.”
While he terms the diamide chemistry “incredible,” Catchot says, “We must be careful to protect it — the very long residual worries me.”
He says the first instance of diamide resistance in the entire U.S. has been documented in Mississippi in diamondback moths. “Before that, resistance in diamondback moths had only been found in the Philippines and Thailand. Although these moths are vegetable pests, these incidents make the point that this class of chemistry is not immune to resistance issues. We know it can happen, and we really need to be careful with our stewardship of these products.”
Last season, entomology specialists had “a lot of questions” about Intrepid Edge, Catchot says. “I felt this product had not been fully evaluated at the university level. On loopers, it looks good. There’s no super-long residual, but at 32 days it was still providing 64 percent control on corn earworm in our assays. It’s as good as anything out there for loopers, at the 4 oz. and 6 oz. rate, and data from Arkansas show it looks good on corn earworm as well.”
Diamond, an insect growth regulator, was also recently registered in soybeans, and has shown good results on stink bug nymphs, Catchot says.
“On southern green stink bug populations in Noxubee County, Miss., last year, we were averaging about 60 nymphs per 25 sweeps. At 6 days after treatment, it looked really good. At 13 days, there was a pretty good fall-off at the lower rates.
“Keep in mind that it will do really well on nymphs, but it won’t control adults, and it appears it will start breaking down after about 10 to 14 days on stink bugs. Then, you’ll have the adults to deal with.” There was also about 70 percent control of caterpillars.