I spent the week still looking for fleahoppers and other plant bugs in cotton. There’s been a couple different species of plant bugs in cotton than I usually see, so feel free to contact me if you have something unusual you would like an ID on. I’ve heard of some verde plant bugs popping up as well.
There are still low numbers of aphids in most fields, but nowhere that warrants treatment. I am hoping after this weekend the rain will be hard on our aphids and will foster some disease in those populations.
Cotton fleahopper numbers are rising in some places this week, and with squaring under way in many fields, we’ll be needing to keep a closer eye out for this pest.
Fleahopper feeding will cause squares to drop. Plants can recover for and compensate for some square loss, but the threshold for fleahoppers is 15-25 per 100 plants. I check for fleahoppers by inspecting the plant terminals once they start squaring. I look at 25 plants per stop in the field, usually checking 100 plants total in an 80-100 acre field, more if the field is larger.
Fleahopper nymphs can be close to the size of aphids, but look like smaller versions of the adults without wings, and are much more mobile than aphids.
The threshold for cotton aphids is 50 aphids per leaf, and if you see the aphid mummies in the field, that’s a good thing.
AgFax Weed Solutions
Parasitoid wasps lay eggs in the aphids, and the aphid forms a mummy while the wasp larvae pupates inside. These wasps, lady beetles, and lacewings all can make a dent in aphid numbers. Treatment for aphids is very rarely justified since the numbers need to be so high before they can cause an economic problem.
If you do decide to treat for aphids, do not use a pyrethroid. Pyrethroids are non specific, and kill predatory insects as well, but aphids will bounce back quickly due to their high reproductive rate.
The chart below contains insecticide suggestions from cottonbugs.tamu.edu (also a good resource) for reference if you have fleahoppers at the action threshold.