I have gotten several calls reporting that aphid infestations are occurring in some cotton fields in northeast North Carolina. To my knowledge, none have been reported from Virginia, but growers should be alerted.
In the ‘old’ days before Bt cotton, we typically treated cotton twice in August with pyrethroids for bollworm. During those years is was not uncommon to see aphid ‘flares’ after those two sprays. We know from ongoing research in soybean that pyrethroids are pretty devastating to most natural enemies (the many insects and spiders that attack and eat pest species). We presumed that the bollworm sprays were suppressing natural enemies and ‘allowing’ cotton aphid populations to build. So, is that what is going on this year in cotton? We cannot be sure or course, but more growers are treating two, even three times for plant bugs and stink bugs, and in most cases they are using pyrethroids. Are these reported aphid flare-ups related to multiple, close-interval pyrethroid sprays? We cannot be sure but if this is the beginning of a trend, we need to reconsider some things, like—are all of the plant bug and stink bugs sprays warranted and based on actual insect pressure; could some be eliminated; should we be using neonicotinoid insecticides (which can help suppress aphids), either tank mixed or as combination products, for one or more of these sprays?
All good questions that will have to be addressed if the aphid situation gets worse. Flaring a bad aphid problem will require more sprays, more money, and more bother. We need to do whatever we can to prevent this problem.
