Insect Pests: What To Expect
Three regional experts offer their thoughts.
By Amanda Huber
Will it be a bad year for insect pest pressure? Three area experts offer their thoughts on insect pest issues this growing season.
Rick Brandenburg, Extension entomologist at North Carolina State University, says that growers in his area are concerned about the hot and dry-weather pests such as beet armyworm, spider mites and lesser cornstalk borers, likely in response to serious problems they had with these pests in 2007.
Expect Hot, Dry Weather Pests
“Lesser cornstalk borer are rarely a problem in our region, and I have no reason to believe they will be in 2008,” Brandenburg says. “The same applies for beet armyworms.”
However, he says to keep in mind that spider mites can be a problem during even short, dry spells.
“The use of the leaf spot advisory to spray only when necessary and using thresholds to treat for worms has really reduced the threat from spider mites in recent years,” Brandenburg says. “Spider mites are a problem when it is hot and dry and we use other products that reduce their natural enemies.”
Something Brandenburg is a little more concerned about is the threat from tomato spotted wilt virus, and he urges growers to be wary of it, too.
“We’ve seen a few more western flower thrips than normal, and the last time we had a serious problem with the disease, we observed the same thing,” he says.
“Growers have been using practices that help reduce the incidence of the disease, but since it has not been a problem for five years, some have relaxed a little on using the best options to minimize tomato spotted wilt virus.”
Watch For Grasshoppers In Texas
“With the dry winter conditions we have had, we are already seeing numerous grasshopper nymphs in wheat fields, and I am anticipating significant grasshopper problems,” Russell says. “As wheat is terminated for planting or dries naturally, nymphs will migrate to greener fields.”
He says peanuts can tolerate significant defoliation. However, in seedling development, try to minimize stress and work to insure rapid development.
Russell says to scout peanut fields weekly for grasshoppers, take note of the insects’ sizes (nymphs are small and without fully developed wings) and note the distance into the field they have moved.
“A chemical application should be considered if grasshoppers are consuming foliage faster than it is replaced by new growth,” he says. “There are several pyrethroids labeled for grasshoppers in peanut, and Orthene 75S and Sevin 80S are also labeled options.”
Russell says, like most insects, grasshoppers are easily controlled as nymphs but more difficult to kill as adults.
Mites Might Be A Problem
“Again with dry winter and planting conditions, I would not be surprised to see large numbers of spider mites late in the season,” he says. “Typically, spider mites are held in check by beneficial organisms, but when we treat for other pests, or some environmental factor goes to their favor, they increase rapidly in peanut fields.”
Russell says to scout peanuts closely for the tiny mites throughout the season. “A 10X to 12X hand lens comes in handy when checking for spider mites.
“If chemical control becomes necessary, Danitol, Omite and Comite II are labeled for spider mite control in peanut.”
Russell reminds growers to be sure to read and follow all label directions and observe the pre-harvest interval.