What is in this article?:
- Kudzu bug has potential to change everything in soybean insect management
- Can cost growers five bushels per acre
- The kudzu bug is poised to change soybean insect management in the Southeast.
- It's expected that kudzu bugs will be present in every Alabama soybean field in 2014.
- Soybean acres have increased in Alabama in recent years.
KUDZU BUGS ARE shown on young soybeans in Auburn, Ala., this past year. The pest is expected to be found throughout the state in 2014.
Can cost growers five bushels per acre
There’s a lot to consider when you’re dealing with this pest and you’ve got a problem, cautions Reed.
“In Prattville, the number per plant varied from zero to six, so they’re not consistent initially on the plant. They start out aggregating on some plants and not getting on others.
“Work done in Georgia indicates that if you infest V-3 soybeans — vegetative soybeans with five per plant — you get a reduction in plant height. Five bushels per acre is a pretty common yield loss for kudzu bugs in a lot of studies that we’ve done.”
With a threshold of 10 per sweep, growers will be spraying some soybeans in early July, and that’ll flare worm problems, but Reed says he doesn’t see any way to avoid it.
“We may be reaching the point on soybeans that we are on cotton in the Mid-South — having to spray to the point to where we’re eating up some of our profits.”
Research at Auburn has discovered a parasitic wasp — the paratelenomus saccharalis — that might be helpful in battling kudzu bugs, he says.
“This is the parasite that I’m optimistic will provide us some help with the kudzu bug,” says Reed.
“It lays its eggs inside the eggs of the kudzu bug. Research at Auburn has shown that 85 percent of the eggs were parasitized in late summer in Auburn. The parasitation rate is highest where kudzu bugs have been the longest.”
Some double-crop soybeans will be planted early enough that kudzu bugs will still be a factor in pest management decisions, says Reed.
“We’re going to have a complex that not only will include stink bugs, pod worms, and defoliating caterpillars, but now we throw the kudzu bug into the mix. We’ve also got Asian Soybean Rust to think about. When in doubt, spray. Kudzu bugs can be controlled with a large number of insecticides. Mostly, growers will use a pyrethroid.”
Looking at Alabama crop acres from 2013, soybeans were the largest acreage of any crop, with the total row-crop acreage pushing 1.5 million acres, says Reed.
Alabama row crops generated $1 billion in receipts for the first time in 2012, he says.
“This year, we expect soybeans to generate $179 million. Soybeans have become an important crop for our producers, and we need to make sure we try and do everything possible to protect this investment and keep the money coming in.”
The first insect pest growers will see on soybeans is thrips, but they don’t do the damage on soybeans they do on cotton, says Reed.
“They can require insecticide treatments on rare occasions. My main worry with thrips is that they vector diseases. Early on, soybean vein necrosis virus can form, and it seems to be more of a problem in Alabama than in other states.”
The three-cornered alfalfa hopper will be the next pest you’ll be concerned about on soybeans, he says. The adults and immatures have sucking mouthparts, and they’ll girdle the plant. The immature stage will be lower on the plant than the adult, and you won’t pick them up very well in a sweep net.
“The main issue we have with this pest from the farmer’s perspective is when the girdling damage is done really early, and the plants fall down making them difficult to combine.”
The three-cornered alfalfa hopper, says Reed, is likely the first pest to cause economic loss in soybeans.
“It’s hard to detect in the very early vegetative stages of the plant. Insecticide seed treatments will reduce the girdling damage for about two to three weeks, so that’s probably the best reason and the only reason to use a seed treatment on soybeans in Alabama. The Mississippi recommendations for three-cornered alfalfa hoppers are probably some of the best I’ve seen.”