What is in this article?:
• The kudzu bug is a new insect pest that has invaded the Southeast and is probing the Mid-South.
• Researchers observed a 19 percent average yield loss in Georgia trials in 2010, and even greater losses in 2011. In five trials yield loss ranged from 22 percent to 47 percent.
• Growers definitely need to scout for the kudzu bug and treat if necessary.
Saw earworm failures
“Last year we saw pyrethroid failures against corn earworm. But we extensively used a Bayer product, Belt, and it was very efficacious on the pest. It also offers long residual control against loopers.
“We’ll also continue to watch stink bugs, even though for the last two years they really have been a non-factor. They have traditionally been our No. 1 pest, but our winters have beaten them back.”
Catchot says Bt soybeans might one day be another tool for soybean growers. “It’s something that we and several companies are researching,” he says. “It’s a potential tool, but there are many issues that have to be talked through from a resistance management standpoint since we already grow Bt corn and Bt cotton.”
Based on an insect pest survey conducted by Extension personnel, Alabama’s most abundant soybean insect pest in 2011 was the three-cornered alfalfa hopper (3CAH), which can cause economic loss even in late season beans.
“You want to treat only when the economic threshold is reached, because an application will take out beneficials and open you up to a worm problem,” says Tim Reed, Alabama Extension entomologist, Belle Mina.
“Based on one study we conducted in 2010, three per sweep — sweeping across two rows — is a treatable level once soybeans reach the R5 stage. We don’t have data on the yield response of soybeans when abundant numbers of 3CAH are treated in the R6 stage.”
Another control option is a seed treatment. “Growers especially need to look at seed treatments if they’re planting soybeans behind wheat and they’re not planning an early season insecticide application,” Reed says.
“Scouting for three-cornered alfalfa hoppers is difficult when beans are just two to three inches tall. So, either use a seed treatment or make an automatic spray when beans are small, if you want to reduce 3CAH damage to young soybeans. The seed treatment also helps in controlling bean leaf beetles.
“Overall, we had light stink bug pressure in 2011, but stink bug numbers increased late in the season when beans were less susceptible to a yield reduction. If we have a mild winter, we might see stink bug pressure pick up in 2012.
“Although three new stink bug pest species were first identified in Alabama in 2010, our survey in 2011 did not detect the red-shouldered or brown marmorated stink bug in soybeans. One red-banded stink bug was found in soybeans in Baldwin County in extreme southwest Alabama in 2011. This pest was also found in soybeans in the same area in 2010 in higher numbers.
“We also sprayed for some soybean loopers in extreme southwest Alabama when the numbers began building in August. We didn’t see a lot of soybean podworm problems. We’re also keeping an eye out for the kudzu bug, which has been found in five Alabama counties on kudzu — but not in soybeans to date.”
Stink bugs, particularly the green stink bug, but also the brown stink bug, are the pest that Tennessee soybean growers are most likely to have to control. Additionally, for the last couple of years, particularly in the Mississippi River bottoms, growers had a significant issue with corn earworms.
“That was definitely our No. 1 pest in 2011,” says Scott Stewart, Extension entomologist, Jackson, Tenn.
“We can do several things to alleviate many insect problems. The first is to plant relatively early-maturing varieties. The Mississippi River often floods, and after the waters recede we plant our Group IVs and Vs. But since they’re planted later than normal, they flower later in the year and they’re set up for both corn earworms and soybean loopers.
“When possible, try to plant in our recommended planting window and avoid planting in late June and July, which gets us in trouble.”
n addition to planting early, Stewart urges growers to use insecticide seed treatments on some of their early planted soybeans.
“Our data show we usually get higher yields when we plant early, and we also get more benefit from insecticide seed treatments. If I were planting early, particularly in no-till situations, from April through most of May, I would use a seed treatment.”
Louisiana’s main insect problems are stink bugs and foliage feeding caterpillars. Early planting always help with the foliage feeders and to some degree with stink bugs, depending on the overwintered populations and how fast they build up.
“We had an unusually high corn earworm year in 2011,” says Jack Baldwin, Louisiana State University Extension entomologist, Baton Rouge. “Just be on alert, particularly when beans start blooming.
“Other than that, it’s just a matter of scouting, spraying, and knowing which pest is in the field and at what levels. If you have a combination of pests, use a product that controls most, if not all, of them, or tank mix another material to take care of the problems — with one application, if possible.”