Cotton Insect Newsletter Vol. 18, No. 10,  July 26, 2000 call 1-877-629-1474 for Cotton Insect Hotline

Cotton Situation: Rain has fallen in many areas of the state during the last several days.   It came just in the nick of time for many cotton fields that were on the verge of cutout.  For others it was nearly too late.   Plants with blooms in the tops don’t have much time remaining to fire up their reproductive systems and set a top-crop of bolls.  Late-planted cotton, which may just be starting to bloom, will profit greatly from the rain. There have been a few more reports of seed rot showing up in South Carolina and folks in Georgia are starting to talk about it as well.  If you want to check for seed rot, you need to examine larger bolls than you would for stink bugs.  Slice the bolls with a sharp knife, making three or four cuts across each boll and one final cut the length of the boll.   Examine the sliced seeds for discolored or dead seed. Also, the seed walls are sometimes thickened and somewhat darker in appearance than would be seen in healthy seeds.  After the inner walls of the bolls adjoining discolored seeds have been examined to ensure there were no stink bug penetration marks or warts- -you can call it seed rot.   We are just not quite sure what causes it yet.  Rest assured, there is a large effort underway to discover what pathogen(s) or “gremlins” are involved. Insect Situation:   Bollworm egg counts were in the neighborhood of 20 to 50 at the PDREC on Monday.  Mike Sullivan said that it was not unusual for scouts to be finding 100+ in cotton fields in the Savannah Valley, especially the irrigated cotton.   I suspect that there are still some fields in the Pee Dee area that are pushing 100 eggs as well.   Stink bugs are showing up in many fields and some farmers have sprayed from 1-2 times already for this pest.   Aphid populations appear to be going down in most areas of South Carolina, and Jack Bacheler, Extension Entomologist at NCSU, indicated to me yesterday that aphid numbers were declining in both early and late planted cotton in North Carolina.   A few more sightings of beet armyworms were reported.  Beets were moving on to cotton plants from pigweed in Dorchester and Calhoun Counties.  Drake Perrow indicated that he was seeing more fall armyworms in the Calhoun County area.  Ron Burnett (FMC) has done some species identifications on eggs we collected at the PDREC.  Of 81 eggs collected on July 18, 75% were bollworms, 23.5% budworms and 2.5% unknown.  On  Monday July 24, 98 eggs were tested and 86.7% were bollworms, 11.2% budworms and 2% were unknown.  Pyrethroid controls have generally worked pretty well up to this point.  One report of control problems came from Marion County, and we are going to collect some survivors and try to determine if they are indeed resistant.   There was an 8-day interval between the first two treatments, and this is probably stretching it too much.  We would prefer to see the interval between the first two treatments at 5 days or less.   Also, I would prefer to go a bit higher than the medium rate on that first spray.  Going with a lower rate will also contribute to poor performance on bollworms. As I have mentioned before, we know that eggs are being laid in the middles of plants now.  Moths will go to the lower portions of the plants to deposit eggs on stems, square bracts, boll bracts, or on dried blooms.  A scout that hasn’t been looking under dried bloom tags in both Bt and conventional varieties may be surprised to see some large worms hanging out of large bolls in the very near future. As I mentioned already, aphid populations are going down over most of the southeastern USA.   Having said this I know some of you are thinking to yourselves, “Roof don’t know diddly squat about what’s going on in my fields - - my plants are covered up with aphids.”  It’s true, there will be fields where the fungus hasn’t shown up yet, the parasites are too little too late, and the lady beetles and other predators can’t go it alone.   And, as T-Bone Moore told me this week, “We can’t stand to put any more stress on our late-planted cotton.”   This is true, and we even considered going for a Section 18 (emergency exemption) for Furadan along with North Carolina and Virginia.   We all decided not to go for it since it would take too long to go through the process and it would be very difficult to declare an emergency in light of recent reports of declining numbers from the Savannah Valley, as well as areas above the lakes and in North Carolina.  In a small test in Marlboro County last Thursday, I saw the fungus take out an infestation of aphids within a 24-hr period.   We knew the fungus was there when the insecticides were applied, but I didn’t expect to see the aphids killed so quickly.   I expect the combination of rainfall, fungi, parasites and predators to bring most aphid populations down within the next few days.  If they don’t, we still have some recommended insecticides that can be applied.  Cotton Listserver:   We have 155+ people using the Cotton Listserver this year.   I put out timely information on cotton insects that comes to the subscriber as email messages.   You have the information as soon as I finish typing it and sending it.  The same message goes instantaneously to each of the 155+ subscribers.   If you are interested in signing up, just let your County Office know or email me using the address shown in the header at the front of this newsletter.  Cotton Insect Hotline: I am also using a telephone hotline to keep growers and others informed about cotton insects.  Each Tuesday and Friday the message is updated.  I don’t always update it at the same time of day, but you can be sure that it will be updated by 5:00 in the afternoon on those days.  This is a toll free number: 1-877-629-1474.  If you forget the number, it is shown in the header of every newsletter.  The Cotton Insect Hotline is sponsored by the SC Cotton Board.  Mitchell Roof  Extension Entomologist

This information is supplied with the understanding that no discrimination is intended and no endorsement by the Clemson University Cooperative Extension Service is implied. Brand names of pesticides are given as a convenience and are neither an endorsement nor guarantee of the product nor a suggestion that similar products are not effective. Use pesticides only according to the directions on the label. Follow all directions, precautions and restrictions that are listed.