Control Of Pests

Entomologist Offers Tips To Ward Off Crop Insects

STONEVILLE, MISS.
   Managing soybean insects was a topic discussed by Dr. Angus Catchot, extension entomologist with Mississippi State University recently.
   Catchot walked through the major pests and showed some efficacy data with different insecticide products used to control each of the major pests.
   “We have about four insects that hit us every year,” he said. “Been leaf beetles have been a persistant problem for us over the last several years and one of the main reasons is because we’re starting to see tolerance to the pyrethroid class of insecticides in the delta region of the state. I think we’re the first ones ever to document this with the bean leaf beetles.”
   He said when growers make a stink bug application in the field and the consultant comes back and checks the field he finds there still are bean leaf beetles in the field. Because of that, Mississippi State started a program about four years ago collecting these beetles. Dr. Fred Musser, a research entomologist, developed a bioassay that was actually able to measure tolerance to the pyrethroids class of chemistry.
   “So now we’re field testing other classes of chemistry to give growers the information they need to make a decision when they apply the insecticides to control it,” Catchot said.
   He also discussed three cornered alfalfa hoppers. That’s always a problem in various areas of Mississippi and it was beginning to show up in higher numbers in mid-July. Catchot discussed the damage and showed some efficacy work. His discussion then moved to stink bugs.
   “Until the last several years, stink bugs have probably been our number one pest,” he said. “They affect more acres in the state probably than any other pest on a wide scale basis.”
   He discussed the different species in the state, including the green, the southern green, the brown. Those are the three big ones, but Catchot also discussed the redbanded stink bug which tends to be moving up from Louisiana.
   “We’re catching a lot more of those in Mississippi now,” he said, offering some control options for stink bugs. He also discussed loopers, adding that in 2008, for the first time in a while loopers was the number one economic pest in Mississippi.
   “Usually in Mississippi we’re a little different than most of the other mid-south states. We tend to plant early and use a lot more Group IVs. With the increasing corn acres, we’re starting to see a lot more later planted beans and somewhat of a shift back to Group Vs. When we push this crop back it sets us up for looper problems because loopers are migratory and they move into the state late every year.”
   He explained the identification and control tactics for loopers.
   Catchot gave a heads up on boll worms, also known as corn ear worms or soybean pod worms.
   “Last year we had a tremendous amount of corn earworms in corn in the state,” he said. “Right now we’re starting to see this generation move off the corn and currently we’re flushing lots and lots of bollworm moths in both cotton and soybeans. This is one that is particularly troublesome in soybeans and one that’s hard to catch because they feed low in the plant canopy and they feed directly on the pod so it’s harder to get them in the sweep net.”
   He urged scouting for corn earworms, adding there has been a threshold change in Mississippi on this particular pest.
   “We moved from 15 to 25 sweeps down to nine based on data out of LSU and other places so we’ve actually moved our threshold,” he said. “I’m going to try to make our growers and consultants aware of that change and give them a heads up that we could be running into some bollworm troubles particularly in beans that are still flowering right now.”
   He said there’s a whole list of products available for use in soybeans, particularly the pyrethroids and the organophosphates.
   “We have the IGRs when we move into looper control,” he added. “However, one thing that our consultants and growers need to be aware of is that one product that works well on one pest may not work good on the next one.
   “With stink bugs we generally use pyrethroids or organophosphates,” he said. “When the populations are made up of mostly brown stink bugs we switch strictly to organophosphates such as acephate or methyl. Soybean loopers always complicate management decisions since they are resistant to the pyrethroids and organophosphates. We generally treat soybean loopers with Intrepid or Steward in Mississippi, and have to add a pyrethroid or organophosphate to the tank to pick up stink bugs.”
   Catchot added that last year in mid-July he saw the lightest insect pressure ever in soybeans in the six years he’s been at Mississippi State.
   “Why, I don’t really know,” he said. “That’s been good, because we had such a late crop we’re thinking on the back end we’re going to start getting into loopers and stink bugs shortly. So we’ve been able to save a little bit of money up front and we’ll be able to use it on the tail end when we really need it, so that’s a good thing.” Δ
   BETTY VALLE GEGG-NAEGER: Senior Staff Writer, MidAmerica Farmer Grower

Catchot talked about the major pests that hit about every year and showed some efficacy data with different insecticide products used to control each of the major pests.