Cotton Insect Newsletter Vol. 21, No. 14, August 20, 2003 Call 1-877-629-1474 for Cotton Insect Hotline

Cotton Situation:  I'm seeing blooms in the tops of cotton plants almost everywhere I look this week.  Most fields planted by mid May are now reaching cutout.  The later-planted cotton plants will be trying to initiate those last few bolls by the end of August.  Although we have had some showers here and there, August has been a much dryer month than July.  The “Crop and Weather Report” from Robert Graham still pegs the state of the crop as 71% good to excellent for the week ending August 17.  The latest figures on certified acreage from Randal Lynch with the Grower Foundation pegs the 2003 cotton acreage at 218,367.    In an earlier Newsletter, I mentioned that a boll is relatively safe from bollworm attack by the time it is about 21 days old.  Fall armyworms may eat their way through somewhat older bolls.  The good news is this: When worms do manage to eat through a more mature boll, they will only damage the adjacent lock.  This means that the remaining locks should continue to develop and fluff out normally when the boll opens.  In fields where plants are cutting out, the majority of bolls will be too tough for insect pests.  The main concern for the next couple of weeks will be protecting the smaller bolls in the tops of such plants.   Insect Situations: The latest Hel ID tests conducted by Candy Roach showed that eggs collected in two fields in Darlington County were over 90% bollworms.  Egg counts have been much lower this week than during the previous week.  Moth numbers are generally down, but we are still getting some fairly hefty catches in a few traps.  I expect to see some increased activity by early next week as many of the third-generation moths that developed in cotton fields and on other host plants begin to emerge.   Female moths will be attracted to lay eggs more in fields with plants still flowering profusely than where plants have essentially reached cutout.  Tender terminal growth provides the most friendly environment for the first instar larvae that emerge from the eggs, but as we have all seen, small worms can also get their start in blooms. We have seen quite a few fields with fall armyworms mixed in with a few large bollworms and budworms.  Unlike bollworms, fall armyworm will feed inside bracts of bolls (bract etching) as well as on the bolls.  They tend to penetrate the lower portions of a boll, near the base, while bollworms tend to feed more away from the base.  Falls do not feed on leaves as do beet armyworms.  There have been a few reports this week about beet armyworms in mixes of large worms, but I haven't heard of any severe damage from these insects alone.   I'm seeing a lot of leafrollers in untreated conventional cotton at the PDREC.  These insects feed on the bracts of cotton squares and bolls.  It's possible for an observer to suspect fall armyworms upon seeing the bract etching.  If you look closely, however, you will notice that the leafrollers produce large amounts of webbing inside the damaged forms.  They may also tie some leaves together, or they may even web fruiting forms to leaves.   Fortunately, these insects are relatively easy to kill, and I suspect that the Bt toxin and the pyrethroids will all do a good job.  In fact, we have leafrollers in the untreated portions of a bollworm test, and they seem to have been controlled very nicely with every material that was used. Stink bugs are still active this week.  We have sprayed a couple of stink bug tests twice now, and I expect to spray one test for the third time on Thursday.  Green stink bug seems to be the predominate species again this week, and probably for the remainder of the season, at least in the Pee Dee area.  Below the lakes, the southern green stink bug often appears in greater numbers in some fields.  As I have mentioned several times before, the pyrethroids should perform adequately against these species, but when brown stink bugs are involved, pyrethroids will not give good control. Whiteflies are showing up in low-to-moderate numbers in a few fields, but I doubt that we will see many problems with this insect.  Moisture and accompanying high humidity appear to be antagonistic to whiteflies.  Back in the days when silverleaf whiteflies were attacking cotton in large numbers, most reports of problems were from the more arid regions of the Cotton Belt.  Hot dry weather has usually accompanied bouts with whiteflies in South Carolina. Glitches:  In my rush to get a newsletter out (#13) on Wednesday, I  neglected to do a thorough job of editing.  At one point, Steward was referred to as equal to the standard Tracer for  budworm control and in the next sentence, poor to fair.  IT WAS RATED AS EQUAL TO TRACER, THE STANDARD.  Then to top it off, I stated that the plant back restrictions against Intrepid have been lifted and  you can plant cotton the year after applying it.  As you all know, you could always plant cotton again.  The real story is:  YOU CAN PLANT OTHER CROPS SUCH AS SOYBEANS, CORN AND WHEAT  THE FOLLOWING YEAR.  My thanks go to Vic Bethea for catching these errors.   Mitchell Roof  Extension Entomologist

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