What is in this article?:
- Cotton insect pests taking backseat to weed, disease problems
- Time of boll damage
- Stink bugs
- Big numbers
- 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.
Time of boll damage
The life cyle of these pests is about 15 days, so they’ve got a lot of feeding to do when they go to bolls, and that’s when they do the real damage, he says.
“There are other caterpillars besides the budworm and bollworm, but we haven’t had any of these on cotton in a number of years.
“One of these is the fall armyworm. We’ve had a lot of armyworms on grasses, peanuts and soybeans in recent years. But it’s a different species of armyworm from what we see on cotton.”
Even though there’s an abundance of grass or rye armyworms on cotton, it doesn’t mean anything because it’s a different strain, says Smith.
“There are currently a lot of armyworms in Florida feeding on corn, and we’re not sure what this means, but they don’t like cotton at all,” said Smith in late June. “And they’re easier to kill on these other crops.”
Armyworms do not lay eggs individually but in masses, and the masses normally are underneath the leaves, he says.
“If I was a cotton scout, I’d stay informed of the ‘big picture,’ but I wouldn’t spend a lot of time looking for armyworms on cotton unless I had heard they were somewhere nearby on cotton.
As they get larger, they’ll go to white blooms, or they’ll be underneath red blooms. If I heard we were having armyworms this year, I’d look for etching on boll bracts. Then I’d look inside there to find the small fall armyworms. We haven’t seen them in a number of years now.
Initially, they’re very green when they’re feeding on this boll bract, but later, they’ll develop some color.”
Alabama growers haven’t seen beet armyworms since 1994 or 1995, says Smith.
“It takes several things to get a huge population of beet armyworms going, and we don’t expect to have those conditions anymore.
“They’re a dry weather pest, but you’ve almost got to be making area-wide applications and suppressing parasitic wasps to get an outbreak.
“On field-by-field applications, you don’t get that total suppression of the parasites that control the beet armyworm. When we had the boll weevil eradication program, we were making applications that were taking out the parasites. Beet armyworms also are more foliage feeders than fall armyworms.”
Another sporadic cotton insect pest is the yellow-striped armyworm, says Smith.
“We see very few of these thanks to Bollgard II cotton, and they’re seldom an economic pest. The Southern armyworm also has been taken out of the picture by new hybrid technology.
The cabbage looper or the soybean looper hasn’t been a problem either since the advent of two-gene cotton. But they were statewide on soybeans this past year.”