Jonathan Croft, county agent in Orangeburg County, reported that “cotton around the seventh week of bloom I checked this week in Orangeburg and Dorchester Counties was above threshold for stink bug injury. I also got some reports of bollworms/eggs in cotton in the area. I didn’t see many in fields I checked.
“Soybeans are about the same as last week. Still a mix of worms and a few green stink bugs. Fields I checked were still below threshold.”
Captures of bollworm moths in pheromone traps increased again, and numbers this past week were higher than they have been in the last several years. I hate being correct about this, but I have stated for the last couple of weeks that the rains would wet the soil and likely release numerous moths from their pupal cells underground.
That prediction continues to come true. As the rains continue, I expect the flight to continue.
Again, keep a watchful eye on 2-gene Bt cotton, especially any that was planted late. The technology seems to be holding up this season, but we have observed square and boll damage over threshold in 2-gene Bt cotton this year.
Egg counts for bollworm were up this week, exceeding 20% eggs and triggering some applications in research plots. We will likely see more injury next week.
Boll damage from stink bugs hasn’t been crazy so far this year, but we still have a few weeks to be largely in the clear. Any cotton planted late will be a bottleneck for stink bugs, so check those fields closely.
There were a ton of stink bugs in soybeans this week, so they are out there in force. Stink bugs should be the main focus of insect management efforts in cotton now and into September.
Defoliation continues to increase as populations of soybean looper (SBL) increase. Other species, such as green cloverworm (GCW), are in the mix, but SBL is predominant now. Read last week’s newsletter for a refresher on how and why you should be able to identify and distinguish between very small GCW and SBL larvae.
More on Cotton
Hopefully, we won’t see large migratory populations of velvetbean caterpillar (VBC) like we did last year. Remember those rare insecticide-resistant VBC from last year? Continue to watch this complex of defoliating caterpillars, and don’t let defoliation exceed 15% once pods are filling.
Estimate defoliation at least weekly. Use a sweep net or a drop cloth to make counts of insects to see what species you have, as insecticide choice depend on proper identification of species.
Podworm (same as bollworm) was abundant in soybeans again this week, so they might also be a factor next week feeding on pods. Also, as pods develop, stink bugs should be the focus of insect control in soybeans.
They are our number one insect pest group of soybeans in the state. Redbanded stink bugs are in the mix again this season, so tank mixes might be needed for this hard-to-control species.