What is in this article?:
- Insect problems in Alabama cotton are taking a backseat to weed and disease issues.
- Stink bugs still could pose a threat under certain conditions.
- Determining an accurate threshold is important in stink bug management.
AUBURN UNIVERSITY EXTENSION Entomologist Ron Smith discusses cotton insect pests with a participant at the recent Cotton & Soybean Scout School held in Autaugaville, Ala.
The green and the Southern green stink bug can be found in Alabama cotton, says Smith.
“I found a lot of green stink bugs last year in central Alabama, and their habits are different from those of the Southern green stink bug, which we mostly see in the summer months.”
Stink bugs, he says, normally feed on cotton bolls that are about 10 days old, are about the size of a quarter in diameter, and are still soft.
“We had a lot of stink bugs on wheat this year, though some of those were the rye stink bug. We had a third consecutive mild winter, and a lot of these should have overwintered.
“In the past two years, the heat and drought in June suppressed their numbers. But a lot of them are building on corn right now. We could be set up to eventually have a bad stink bug year. They have the potential to be the most damaging insect in cotton in the Southeast.”
If they do come into cotton fields prior to about the third week of bloom, when the first soft bolls are on the plant, they will go to younger fruit, says Smith.
“I guess it’s debatable whether they will go to squares, but there’s not much evidence that stink bugs will feed on squares.
“We don’t have to be many weeks into bloom to have small thumb-sized bolls, and I can assure you a stink bug can find each one of those. If those are the oldest vegetation out there, they’ll make mush out of them.
“This year, we could have stink bugs before we have 10 to 12-day-old bolls. If so, you won’t have 10 to 12-day-old bolls because the stink bugs will get them all.”
The classic sign of stink bug damage is an indention on the boll, says Smith.
“And when we normally see that, we look internally to see if there is any deteriorating tissue where the stink bug is trying to feed through to the seed to get to protein. Boll rot organisms are introduced as it is feeding, and you’ll eventually get boll deterioration from the inside.”
If weather conditions are wet in August and there is a lot of stink bug feeding, you’ll see yellow-stained lint where moisture gets into the boll, says Smith.
“We had that several years ago when we first starting planting Bollgard cotton and didn’t quite know what it was. But you’ll need a really wet year for these conditions to form.”
One other insect that does damage very similar to that of the stink bug is the leaf-footed bug, normally found farther south, says Smith.