It is possible some of the pests you encounter in your cotton fields this year could be resistant aphids. NCSU entomologist Jack Bachelor points out resistant populations of aphids have been giving growers in the Mid South a difficult time in recent years and he notes this resistance is now being found in our area of the world, too – that is, the Virginia-Carolina region. Samples of aphids have been collected in North Carolina, he says, and these have been sent to Mississippi where they were confirmed for resistance.
"I think we have been seeing a little bit of this in North Carolina in the past few years," Bacheler says. "You have the possibility, if you have treatable aphids, of not being able to control them with the materials you have been using. I don't know how high that probability is but there is a chance of that."
The resistant aphids are not killed by chloronicotinoid pesticides and those, for the most part, are the products that growers have traditionally used to treat aphids. Bacheler says the common insecticides used for this purpose, in order of rated effectiveness on a scale of 1-5, are Intruder (4.3), Carbine (4.3), Centric (4.3), Admire Pro (4.0) and Belay (3.0). Unfortunately all of these, with the exception of Carbine, are choronicotinoids (also called nics or nicotinoids).
Carbine is from FMC and has the active ingredient flonicamid (which comes from the chemical family pyridinecaroxamide). It is labeled in N.C. and S.C. as well as AL., AR., AZ., CA., FL., GA., KS., LA., MO., MS., N.M., OK., TN., and TX.
It works by stopping cotton pest from feeding within one hour of exposure, ending crop damage in a timely way. And, FMC also notes it is gentle on beneficial insects.
"If you have an aphid population, you spray once, and you're not satisfied with the control, there is a good chance there is resistance in the population," Bacheler says. "And that (Carbine) is probably the chemical of choice."