What is in this article?:
- Plentiful rain brings disease to Alabama soybeans, cotton
- Gulf Coast is exception
- Found first on lower leaves
• “Soybeans are looking pretty good, and we’ve got planting dates stretched out from early beans that are close to being harvested and late beans, including some that weren’t planted until Aug. 10, in south Alabama,” said Dennis Delaney during the recent East Alabama Crops Tour.
• If you grow cotton after cotton, you’ll have Corynespora leaf spot. If you’re in a reduced-tillage system when you’re in continuous cotton, you’re even more likely to have it.
• The other factor is irrigation.
THE SAME WEATHER conditions that are good for soybeans also are good for the development of Asian Soybean Rust, explains Auburn University Extension Soybean Specialist Dennis Delaney during the recent East Alabama Crops Tour.
Gulf Coast is exception
“The only exception was the Gulf Coast, where yield fell off after the first planting date. It’ll take several years to come up with good data from that study.”
As far as insects across the state, kudzu bugs continue to be a concern, says Delaney.
“They come in through northeast Georgia. They’re a stink bug, but they don’t affect pods like other stink bugs. They’re more like aphids — if there are enough of them, and a high-enough population, they’ll suck the juice out of the plant, but it takes a high population to do that.
“So if you see a few here and there, don’t get too excited. We haven’t had them in the U.S. long enough to really get a good handle on them. But in Georgia and North Carolina, they’re advising to just wait.
“The migration of adults won’t happen for about a month or so, so if you spray early, you’ll probably be spraying again and again, killing the beneficial insects. You probably should wait until you start seeing the nymphs and the egg masses. You might can get by with just spraying once.”
Corynespora leaf spot, a disease which researchers know little about, can be devastating in a cotton field, says Austin Hagan, Auburn University Extension plant pathologist.
“We’re used to seeing some leaf spot in a field, especially as we get towards the end of the season and potassium levels are low, but this is a little bit different.
Corynespora started out in Georgia about five years ago, he says. “They’ve had problems with it there, it moved into Alabama last year, and there’s a good deal of it this year.
“Just from observations, it appears the disease is rotation related. In other words, if you grow cotton after cotton, you’ll have it. If you’re in a reduced-tillage system when you’re in continuous cotton, you’re even more likely to have it,” says Hagan.
The other factor is irrigation, he adds. “It seems to be much more of an issue in those areas that get a lot of water. When you get down to Baldwin, Mobile and Escambia counties, where they get afternoon showers most every day, they don’t need irrigation to have issues with this disease, and they’re having a lot of problems with it right now.”
This disease “came out of nowhere,” says Hagan, and wasn’t an issue in the past.
“At this point in time, we really don’t have much information concerning management of the disease. We’re basing our information of the disease on experiences we’ve had with other foliar diseases in other crops. This is more of an infectious disease than those other leaf spots you see in cotton,” he says.