For at least the next month, we will be looking primarily for stink bugs, spider mites, and important leps (bollworm and fall armyworm) in the crop. Injury to bolls by stink bugs should now be the main focus of scouting efforts, but pressure from bollworm is on the rise. Trap captures are up again this week.
I think that we can now stop talking about aphids. Despite the hot, dry weather, it seems that the fungus, Neozygites fresenii, that decimates populations of aphids has finally starting helping. In the photos below, you can see the fungus (light tan color – photo by Justin Ballew) responsible for the epizootic and the secondary fungal pathogen (dark gray) that quickly grows on aphids killed by N. fresenii (the secondary fungal growth is a good indicator of aphids killed by the “aphid fungus”).
Here are the last items we will cover regarding aphids in cotton in the 2015 newsletter. I am done with aphids in cotton for this year, and I hope that most everyone else is also now that the “fungus is among us” finally.
On July 14, I put out an insecticide efficacy trial on cotton aphids with Andrew Warner, county agent covering row-crop issues in Hampton County and surrounding counties. At 3 days after treatment (DAT), Bidrin, Carbine, Assail, and Transform provided the best and quickest reduction in aphid numbers, but most of the other products, except for the pyrethroid (bifenthrin – Brigade in this trial), also reduced aphid numbers significantly.
At 8 DAT, the only products still providing very good control of aphids were Bidrin, Carbine, Assail, and Transform. We pulled the flags from the field after this rating because the fungus was taking the population of aphids down pretty quickly. I doubt that aphids caused enough yield loss in this field to justify the expense of an aphid spray, but this was one of those cases where the populations were high, and they could have stayed high, if the fungus did not establish in the field.
But, in 7-10 days, nature corrected the imbalance, and all we had to do was wait. Data are good, though.
Kudzu bugs, various species of caterpillars, and stink bugs are in the mix. If you have blooms and pods, you need to be looking hard for corn earworm (CEW) and stink bugs. Know how to identify the caterpillars and moths you flush. Insecticide choice (i.e. the amount of $ you spend) depends on the species. You can control green cloverworms (GCW), CEW, and green stink bugs with pyrethroids, but you will need to use a more specific insecticide for soybean looper (SBL) and tobacco budworm (TBW).
All of these species should be flying around now as adults and eating as immatures. Monitor defoliation levels, but you must be able to identify the species. Numbers of TBW moths detected in pheromone traps increased this past week. Trap and picture of TBW moth below.