Pesticide Potpourri

• Labels are constantly changing, and it is wise for the end user to read the entire document even if they are familiar with the product.  One interesting label we at the PIO observed is that for Allectus®, which is combination of bifenthrin and imidacloprid that pest control operators would likely purchase for use.  Under the “General Information” section of the label, it states “Not for use on plants being grown for sale or other commercial use, or for commercial seed production, or for research purposes.”  This is the first label known to the PIO that contains language the expressly forbids use in research.  If you are aware of others, please contact the PIO. 
•  Feeding by the western flower thrips, Frankliniella occidentalis, causes damage to the fruits of pepper, and the species is the key vector of tomato spotted wilt virus.  Effective management integrates conservation of populations of the natural predator, Orius insidiosus, with the use of reduced-risk insecticides, namely spinosad.  Experiments were conducted in northern Florida in 2005 and 2006 and in central Florida in 2006 to evaluate the new reduced-risk insecticide spinetoram for control of thrips and to determine the impact on natural populations of O. insidiosus.  Spinetoram at 61 g ai/ha was as effective as spinosad at 140 g ai/ha against the western flower thrips and the other common thrips in Florida, Frankliniella tritici and Frankliniella bispinosa.  The mean numbers of the predator were very high in all treatments in each experiment, and their numbers relative to the numbers of thrips indicated that predation was sufficient to suppress thrips populations in all treatments.  Broad-spectrum insecticides when included in the experiments provided little or no control; sometimes, they flared thrips numbers compared to untreated pepper.  (Plant Health Research, 1/18/08). 
•  A new disorder of tomato has been observed in Hillsborough and Manatee counties since 2006.  Symptoms being about four weeks after transplanting and consist of an interveinal purpling of the upper leaf surface of individual petioles that gradually spreads to the entire leaf blade.  When two leaves overlap, the disorder only develops on the surfaces exposed to sunlight with the shaded leaf tissue remaining green.  Afflicted leaves appear to decline and senesce prematurely.  It seems to be more noticeable in grape tomato.  A causative pest has not been implicated in this disorder, and it is possible that it is linked to crop management.  On the affected farms, the crop was routinely sprayed twice or three times per week with a variety of products (up to five at a given time) in a tank-mix.  While some manufactures examine two or popular three-way mixtures, four- and five- component mixtures are generally not examined.  Growers and scouts can contact Dr. Gary Vallad or Dr. Bielinski Santos if this disorder is suspected.  (UF/IFAS Pest Alert).   
• Scientists believe they have found the first confirmation that insects have developed resistance to genetically-modified crops.  University of Arizona entomologists looked at data from six experiments to monitor pests in fields sown with transgenic cotton and corn in Australia, China, Spain and the U.S.  They found evidence of genetic mutation among bollworms in a dozen cotton fields sown in Mississippi and Arkansas between 2003 and 2006.  But no such evidence was found among five other major pests monitored elsewhere.  The type of Bt toxin to which these bollworms have become resistant is Cry1Ac.  Lead researcher Bruce Tabashnik said a new variety of Bt cotton was successfully combating the resistant bollworms as it combined a second toxin, Cry2Ab, with Cry1Ac.  On the other hand, the paper, published Nature Biotechnology, found no evidence of resistance among the other insect pests being monitored.  They remained susceptible to Bt toxin.  Worst-case scenarios sketched by critics of GM crops have predicted pests would become resistant to Bt crops in as little as three years, said Tabashnik.  “The resistance occurred in one particular pest in one part of the U.S.,” Tabashnik said.  “The other major pests attacking Bt crops have not evolved resistance.  And even most bollworm populations have not evolved resistance.”  (Agence France Presse, 2/8/08). 
• Late blight of potato, caused by Phytophthora infestans, is one of the most devastating diseases of potato.  A major late blight resistance gene, called RB, previously was identified in the wild potato species Solanum bulbocastanum through map-based cloning.  The full-length gene coding sequence, including the open reading frame and promoter, has been integrated into cultivated potato (S. tuberosum) using Agrobacterium-mediated transformation.  The RB-containing transgenic plants were challenged with P. infestans under optimal late blight conditions in greenhouse experiments.  All transgenic lines containing RB exhibited strong foliar resistance.  Field-grown transgenic tubers also were tested for resistance to P. infestans.  In contrast to the foliar resistance, RB-containing tubers did not exhibit increased resistance.  Two years of field trials were unable to detect any significant effect on tuber size or yield after addition of the resistance gene to several S. tuberosum cultivars.  (Plant Disease, Vol. 92, No. 3). 
•  In mid-February, the International Service for the Acquisition of Agri-biotech Applications, and industry-supported nonprofit that promotes the use of biotechnology around the world released a report that found widespread adoption among developing countries.  Specifically, farmers in 12 developing countries planted biotech crops in 2007, exceeding for the first time the number of developed countries.  Of the 12 million farmers worldwide who sowed genetically-engineered seeds, 11 million were described as “resource poor.”  (Gainesville Sun, 2/14/08).