South Carolina Cotton: Bollworm Moths Active…But Will It Matter?

Photo: Texas AgriLife Extension

Charles Davis, county agent in Calhoun County, reported that it is difficult for him to find aphids in cotton now because of the natural fungus taking them out. He saw plenty of lady beetle pupal “skins” attached to leaves that completed their development after doing all they could in eating aphids.

Fleming McMaster, local crop consultant, reported earlier this week that he is triggering thresholds for stink bugs in cotton he has in the third week of bloom.

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He also reported it being pretty quiet in the soybean fields he is checking.

Tom Smith, local crop consultant, reported that “last week we began treating a few fields for the sucking bug complex. This week activity has jumped quite significantly, particularly with cotton fields nearest corn and peanut fields as you would anticipate. Have been observing both green and brown stink bug species with a few tarnished plant bugs in mix as well.

In some fields, “boll hits” have more than doubled from last week to now.

“The aphid fungus is spreading now but still varies from field to field. No sightings of spider mites yet, but I’m expecting to see them shortly in some fields unless rains become widespread. Bollworm moth sightings also picking up…lot of corn fields drying down now.”

Tom also saw some southern green stink bug nymphs feeding on squares, adults mating, and predatory stink bugs and spiders out there trying to help us.

Cotton Insects

Things changed quickly in the past week. Bollworm moths are very noticeable flying around in blooming cotton, and trap captures went up again.

I think we are higher now with trap captures than we were all last year, and activity is likely going to pick up more in the next couple of weeks. Eggs are more easily observed now.

We observed caterpillars and injury in non-Bt cotton in my plot work this week, but the 2- and 3-gene Bt cotton seems to be holding up well, although we still detected some injury.

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The first couple of weeks of bloom are critical for finding bollworms escaping control from in-plant Bt toxins. Continue to scout for eggs, injury to squares, and look for damage to and larvae in white blooms and bolls, as well as under bloom tags, particularly on 2-gene cotton.

We did see larvae in blooms on non-Bt cotton, and a few of them were rather large. We also found a few odd things in the field today that you don’t see on every field visit. For example: a hatching egg mass of saltmarsh caterpillars.

Populations of cotton aphid have crashed in a big way due to the naturally occurring fungus, Neozygites fresenii, in some areas. Are you glad you didn’t spray for aphids now? Saving input costs and having Mother Nature help out is a good deal.

I have yet to see widespread symptoms of the viral Cotton Leaf Roll Dwarf Disease (CLRDD) transmitted by cotton aphid. That is also a good thing.




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