Comment submitted by B. Roger Leonard, LSU AgCenter

August 19, 2006 Dear Sir, This letter is written in support of the re-registration materials for carbofuran (Furadan 4F) in cotton. During 2006, Louisiana producers began to experience cotton aphid, Aphis gossypii Glover, control failures when using the standard neonicotinoid (Trimax, Centric, and Intruder) insecticides. Several of the state?s licensed agricultural consultants recognized cotton aphid control failures during early June. The first report came from Mr. Roger Carter in central Louisiana who expressed concern over product performance in a telephone call on Friday, June 9, 2006. Mr. Carter is a respected professional consultant with over 30 years of experience in Southern row crops. Reports from additional consultants in Louisiana during following days substantiated Mr. Carter?s observations. The control levels in those treated fields were not absolute failures, but less than satisfactory control. Many of those fields required re-treatment within a few days due to dry weather conditions that exacerbated the cotton aphid problem. Even more consultants across Louisiana indicated reasonable, but less-than-expected performance, against low to moderate populations of cotton aphid with recommended products, but only when used at their highest labeled rates. Mr. Carter?s report was indicative of the cotton aphid situation not only in Louisiana, but of future problems in Mississippi and Arkansas during 2006. The Louisiana Cooperative Extension Service has a list of products recommended to control this pest that includes an OP (Bidrin), three neonicotinoids (Trimax, Centric, and Intruder) and a new compound, Carbine. Cotton aphid resistance levels to Bidrin have prohibited the use of this product across most of the state. The remainder of the compounds on the list must be absorbed into plant tissue and/or move by translaminar activity to provide optimum control. Much of Louisiana experienced extremely droughty crop conditions during 2006 and cotton plants did not absorb enough of the product to provide optimum activity. The true contact activity of the these products is fairly low and not sufficient to provide satisfactory control without perfect coverage and plant uptake. Research trials during 2006 in Winnsboro, Louisiana, indicated that the neonicotinoids and Carbine at high rates significantly reduced very high numbers of cotton aphid numbers (>200/plant terminal) at 3 days after treatment (DAT), but none of the products completely cleaned up the problem and considerable numbers of aphids were still alive. The efficacy of the products were likely affected by the current drought-stressed conditions of the plants. These plots were rated again at 7 DAT and control at the highest rates improved. By 11 DAT, cotton aphids had re-infested plants at level that in a commercial field, re-treatment would have been required. Other tests also showed the residual of these compounds were less that what we have obtained in the past. These products historically and typically exhibit residual efficacy that persists for >14 days. Across the Mid- Southern US, most cotton fields are only treated one time. By that point in the season, populations crash due to an insect pathogenic fungus. Presence of the fungus was not been detected in our samples until mid-to-late July. These were June problems. Our records indicate that it usually occurs during late June or early July. Cotton aphid control was a serious problem for many farmers of Mr. Carter and other consultants across Louisiana during 2006. I tested Furadan and its efficacy though contact and systemic activity was the equal to or better than all other compounds tested. Most cotton entomologists had hoped with the registration of Centric and Intruder, Furadan would not be needed for this pest. Prior to their registration, Furadan was the only product that consistently provided satisfactory control of cotton aphid. From initial registration of these neonicotinoids through the 2005 season, Furadan was not needed. During 2006, an emergency need in Louisiana prompted state and federal regulatory agencies to allow the temporary and restricted use of Furadan on limited acreage. Furadan use was only allowed in accordance with previously established guidelines that confirmed field control failures against cotton aphid after trying and using other available products. Furadan was successfully used in the 2006 emergency situation with few problems. This strategy was similar to the carbofuran emergency use patterns for cotton aphid previously approved by those agencies. I do not feel that Furadan should be used, unless the need is absolute and necessary to protect the crop in the absence of alternatives. Presently, the future of the alternative chemistry is questionable. Preliminary results from the USDA- ARS at Stoneville, MS, indicate that some cotton aphid populations are expressing tolerance levels to the neonicotinoids that could lead to unsatisfactory control in cotton fields. This insect has a propensity to develop resistance to insecticides and with the reliance on a single class of chemistry, this effect was ultimately expected. FMC?s new insecticide, Carbine, certainly has expressed satisfactory performance against cotton aphid in research trials, but it is unlikely to be a sustainable tool without alternative insecticides with novel modes of action. The agrochemical industries are valiantly searching for insecticidal molecules, but to the best of my knowledge, there are none within a few years of commercialization. Finally it is important to remember that cotton aphid is an annual pest and limited areas across the Cotton Belt require insecticide applications each year. Therefore, given the 2006 situation and my future expectations of cotton aphid problems, I sincerely request that the registration status of Furadan in cotton be maintained in such a manner that it may be used in emergency situations, for short term use, on limited acreage. If you have suggestions/questions concerning this issue, or I can assist you in anyway, please contact me. B. Roger Leonard, Professor LSU AgCenter Dept of Entomology/NERS 212 Macon Ridge Rd Winnsboro, LA 71295 rleonard@agcenter.lsu.edu Tel. (318) 435-2157 Cell (318) 334-0147 FAX (318) 435-2133