Cotton News Letter Vol. 18, No. 9,  July 19, 2000

Cotton Situation: Most cotton fields have at least begun to set bolls now. I'm seeing a lot of cotton that is approaching cutout, with anywhere from 2-5 nodes above white bloom. In fact, most of my cotton here at the PDREC is in that boat. We sprayed some cotton for bollworms this morning that had 2-3 nodes above white bloom. Mike Jones found a field of DPL458 BR in Dillon County with bolls that exhibited the same symptoms that were seen last year during the seed rot epidemic. It's too early to say how widespread seed rot will be, but there was an earlier report of seed rot being found in Texas. Last year, South Carolina was about the only state that admitted to having a seed rot problem.  Insect Situation: As expected, bollworms and budworm moths continued to lay eggs in cotton this week. There have been a few reports of 100 or more eggs/100 plants, but for the most part egg counts have been in the range of 10 to 40/100 plants in the Pee Dee area. Some growers are treating Bt cotton for large worms (1/4" or longer) in the Savannah Valley. Stink bug damaged bolls were found at economic levels in Dillon County. Aphid infestations are still hanging in there, tempting some farmers to attempt to control them with insecticides. Numbers of beneficial insects and spiders were at a high level in most fields that had not been treated. I just received a report of beet armyworm infestations in Calhoun and Dorchester Counties.  Our 12 pheromone traps in the Pee Dee area averaged about 17 bollworms on Monday, with a high of 51 for a five-day period, which is lower than expected. Mike Sullivan said that moth catches were heavy in Barnwell and Bamberg Counties early this week. Most conventional cotton was treated for the second time this week in the Savannah Valley. They were finding 20-80 eggs per 100 plants in Bt cotton, with small worms in blooms running 6-45. More eggs were being found in the irrigated, lush cotton. Some Bt cotton was being treated for big 2nd instars (>1/4 ") in purple blooms.  I haven't heard any reports yet of bollworms that were not being controlled with pyrethroids. It's unlikely that pyrethroid resistant bollworms have retreated, so if you are having problems we would like to know about it. Call your County Agent and he will let Tommy Walker, Mike Sullivan, or myself know about it, so we can collect some worms.  Stink Bugs/Seed Rot: With the seed rot problem that we experienced in 1999, and with symptoms showing up already in 2000, it becomes very important to distinguish between seed rot and stink bug damage. We suggest pulling at least 25 quarter-sized bolls per field and examining these for stink bug damage. Stink bugs can't damage a boll without inserting their beaks to get to the seeds. When they do this, they leave a puncture mark or a warty growth on the inner boll wall. If you start seeing discolored seed or dead seed, in the absence of stink bug punctures or warts, then you should suspect seed rot. I suspect that we have had some cotton fields sprayed for seed rot in the past, where stink bugs were not really a problem. Aphids: The first appearance of Neozygites fresenii, the fungus that attacks aphids, was confirmed from aphids collected last week in the Savannah Valley. It shouldn't be too long before the disease brings most aphid infestations down across the state. Boll Weevil Containment: The Technical Advisory Committee for the Boll Weevil Containment program met at the PDREC near Florence on July 18. Jim Wilson reported that Virginia, North Carolina, and South Carolina were all weevil free so far. There has been only one weevil captured in Crisp County Georgia, where there was an outbreak last year. Things weren't going quite so good in Mississippi and Tennessee, where weevil numbers had been much higher than expected. High population of boll weevils had moved out of Regions 1 and 2 in the Mississippi Delta to infest Regions 3 and 4. Mississippi was in the process of borrowing $12 million to cover the shortfall created because of the large acreage that was being treated for boll weevils. Randy Lynch said that all fields should have traps up by now. Trappers were in the process of making their first trap run. Some acreage was found without traps in Clarendon County, where the grower had apparently neglected to report intended cotton acreage. If you see cotton fields without traps, call 1-800-269-9928 and let Randy or other program personnel know the locations. Jack Jackson said that farmers with failed cotton fields were being given a little more time to destroy their fields without paying assessments. It's very important, however, that all the plants in such fields be totally destroyed. If there are cotton plants remaining, the program will have to continue to trap those fields.  RR Cotton in RR Soybean: Last year, 12 soybean fields were found with volunteer cotton plants growing in them. These fields weren't noticed until the cotton bolls began to open. This could be too darned late if a hitchhiking female dropped in and laid some eggs in early July. Her offspring could be spread over a fairly wide area before a pheromone trap next to a real cotton field ever caught one. It's not just South Carolina - - this is getting to be a bigger problem in other states as well. Jim Wilson said they had found several fields in Georgia this year where 2000 soybeans were planted behind 1999 RR cotton, and there were volunteer cotton plants. They have also found a considerable acreage of pine seedlings infested with cotton plants. If you see any of these situations developing, call me or call Randal Lynch at 1-800-269-9928.  Mitchell Roof                                                                  Extension Entomologist

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