What is in this article?:
- Kudzu bug: Increasingly a pest in southern soybeans
- Keep tabs on disease situation
One thing Reed says he’s encountered this past year was that just about every field had kudzu bug in it, but you might not pick up but one per sweep, or one per 20 or 25 sweeps.
AUBURN UNIVERSITY EXTENSION Entomologist Tim Reed scouts a soybean field in northeast Alabama. He expects the insect pest to be statewide on Alabama soybeans in 2014.
Keep tabs on disease situation
The critical decision comes when you’ve got disease and insect problems in a field, says Reed.
“You might make a decision to spray a fungicide and bide your time to see what the disease does. That’s when it becomes more difficult to make a decision to apply an insecticide.
“If they’re R4 or early R5 soybeans, there’s still time for worms to get bad, and if you spray and kill all of your residuals, it may increase the worm problem.”
Some consultants are cautious about spraying soybeans with sub-threshold levels of insects because of podworms, he says. “If podworms get down in the bottom, you can’t get them with a sweep net, and they’ll chew on the beans and hurt yield.”
Reed advises growers to look at their fields closely, having a good idea about insect densities.
“Keep tabs on the disease situation. When disease starts showing up and is spreading to a wider area, you need to spray for soybean rust if you haven’t already. Before soybean rust was being detected, some fields were going to be sprayed anyway because the yield potential was so good at R4 or R5.
“Go by a field-by-field situation, and if you’re making good sweep net counts and have a good grasp on the insect populations, then use that to make your determination. If you just look down the plant, you can see them, and if you see a lot of them, then you need to spray.”
Auburn University researchers have found a wasp parasite that is doing a good job on the kudzu bug, says Reed, and that might be part of the answer to this pest.
“In South Carolina, they’ll have a problem one year and not the next, so hopefully we’ll have that same situation. Kudzu bugs feed mainly on the stem, but they’ll feed on any part of the plant.
“In 24 Georgia studies, the average yield reduction from this pest was five bushels per acre. When I started spraying for them during the last week of June in Prattville, they would build back up in two weeks.
“You’ll see that until the first week of August. They continue to move around and get on beans that are in the early vegetative stage.”