What’s Buggin’ Your Fields?

Misidentification proves a costly mistake, valuable lesson learned.

By Amanda Huber
 

In 2008, peanut fields were marched upon with a fierce vengeance by tobacco budworm. They struck early and repeatedly, with three destructive generations of budworms occurring in many fields. Adding insult to injury, many producers treated the pest incorrectly, costing them in more ways than one. It should be a good learning experience.

How Could You Know?
“The onset of problems was unusual in that the first infestation at economic levels was in peanuts that were less than six inches across,” says David Adams, University of Georgia Extension entomologist. “At least 40 percent of the acreage was treated once, and 15 percent was treated two or more times.”

However, Adams says, there was an expensive lesson learned because the early treatments were made with an ineffective insecticide for the budworms. The reason, unfortunately, was that most producers thought it was a different pest.

“Most growers were thinking that they had a corn earworm infestation and used a pyrethroid without success. Pyrethroids are not effective against budworms, and the budworm, to the naked eye, looks identical to the corn earworm.”

Besides the pests looking identical, Adams says it was an easy mistake because budworms have never been an economic issue in peanuts before 2008. “Let’s hope last year is not the beginning of a trend.”

Try, Try Again
Tobacco budworm problems were not confined to Georgia. Alabama producers, too, had to do battle with them. Ron Weeks, Extension entomologist, now retired but who has continued to work with Auburn University, says producers, particularly those in the Wiregrass area, faced some severe foliage-feeding worm activity.

“It was somewhat spotty, but where it occurred, it created some control problems,” Weeks says. “It was primarily cutworms and tobacco budworm populations.”

As was the case in Georgia, Weeks says tobacco budworms were treated in many cases with pyrethroid chemistry, which did not work.

“Tracer was effective, but in short supply in most areas,” Weeks says. “We wound up getting effective results with Steward or Lannate for these particular pest problems.”

Risk Indexes Working Well
As in other Southeast states, tomato spotted wilt virus was at a very low level last year in Alabama, says Weeks.

“The increased use of resistant peanut cultivars and planting-date changes to avoid thrips damage along with adoption by growers of the TSWV risk index, now a part of Peanut Rx, has made a big difference in damage to peanut yields by TSWV,” he says.

Rick Brandenburg, North Carolina State University Extension entomologist, says the adoption of practices shown to lessen the incidence of TSWV has helped tremendously in his area as well.

Burrower Bug

A pest problem that has surfaced, or more accurately “dug in,” is the burrower bug, Pangaeus bilineatus.

Adult burrower bugs are oval-shaped and about one-quarter inch long. They are dark brown to black except for the ends of the wings, which form a transparent, silvery diamond shape at the rear of body. Nymphs are smaller, dark brown and have the same general body shape.

David Adams, UGA Extension entomologist, says this bug continues to plague peanuts that are grown in no-till culture, especially in non-irrigated situations.

“Our latest recommendation is that in fields that have developed a history of problems, the only realistic approach to control is returning to conventional tillage practices such as deep-turning,” he says. “Chemical approaches to control have had very limited results.”

In a fact sheet on burrower bug, prepared by Jay Chapin, Extension entomologist and professor, and James Thomas, agriculture science associate, with the Department of Entomology, Soils and Plant Sciences at Clemson University, the authors say that damage also appears to be correlated with drought stress. Therefore, irrigation, tillage and the use of a cover crop is recommended.

For more information on damage and treatment options, the burrower bug fact sheet can be found at http://entweb.clemson.edu/eiis/pdfs/ag32.pdf, or email Jay Chapin at jchapin@clemson.edu.
 

“Thrips have always been a problem in the Virginia-Carolina area because we have a shorter growing period, and they stunt the peanut plants. Our earliest-planted peanuts have a tendency to get hit pretty hard.

“Our farmers have done a very good job using our tomato spotted wilt virus index (modified from Georgia), so we have been very fortunate with regard to the level of virus we have seen in the last six years,” he says. “I think our growers are following the rules, and this has really helped.”

New Labels
Although new labels are few and far between in the peanut industry, producers have new options for insect control.

Brigade received a label for thrips, leafhoppers, threecornered alfalfa hoppers and some foliage-feeding worms. Dimilin is now labeled for velvetbean caterpillars, armyworms and lesser cornstalk borers. Intrepid received a label for beet armyworms.

Remembering the lessons learned from 2008, producers should be absolutely certain that they know the pest problem in their field before deciding on what product to use for treatment. A phone call to an Extension agent or entomologist and even a field visit is a small price to know the treatment applied will work on the specific pest causing the problem.

PG