Browsing Cotton Report 2004 by Subjects
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Comparative Efficacy and Selectivity of Acetamiprid for the Management of Bemisia tabaciThe integrated control concept emphasizes the importance of both chemical and biological control for pest suppression in an agricultural system. A two-year field study was conducted to evaluate the selectivity of acetamiprid for controlling sweetpotato whitefly, Bemisia tabaci, in cotton compared with a proven selective regime based on insect growth regulators (IGRs) of pyriproxyfen and buprofezin. Acetamiprid was highly effective in controlling all stages of B. tabaci compared to our untreated control and generally produced lower pest densities than the IGR regime. However, six of 14 taxa of arthropod predator were significantly depressed with the use of acetamiprid compared to our untreated control, including common species such as Geocoris punctipes, Orius tristicolor, Chrysoperla carnea, Collops vittatus, Hippodamia convergens, and Drapetis nr. divergens. Compared to other independent and concurrent studies using mixtures of broad-spectrum insecticides at the same research site, acetamiprid depressed fewer populations of predator taxa in our study, but for those taxa affected, reductions from acetamiprid were larger in many cases. In contrast, only one species was significantly reduced in the IGR regime compared with the untreated control. Predator:prey ratios were generally depressed with the use of acetamiprid compared with both the IGR and untreated control regimes. Parasitism by aphelinid parasitoids was unaffected or depressed slightly in all insecticide regimes compared with the control. Although highly efficacious for whitefly control, our results suggest that acetamiprid is a poor substitute for IGRs currently used in an integrated control program for B. tabaci in cotton.
Search for Effective Chemical Controls for Lygus Bugs and Whiteflies in Arizona CottonWhiteflies and Lygus bugs continue to be key pests of Arizona cotton. Some of our most popular and time-tested chemicals are still providing efficacy toward Lygus or whiteflies when used in a timely manner. However, promising new chemicals may also become available in the near future. Through research, growers can be kept updated on options for successful IPM. An experiment was conducted in order to expand our knowledge of currently available compounds and upcoming advances in insecticide development. In this experiment, 11 different compounds were tested for efficacy and duration of activity against whiteflies, Lygus, or both. Although none were active on Lygus adults, some chemicals were very effective on all stages of nymphs. Orthene® or Vydate® continue to show good results against Lygus but did not yield as high as one new compound. The best performing insecticide against Lygus was flonicamid, a novel chemistry under development by FMC. This insecticide had the best control over Lygus nymphs, was the highest yielding treatment, and required one less spray than other top performing compounds. Among newer chemistries for Lygus control is fipronil (Regent® by BASF), which performed slightly better than Vydate but not quite as effective as Orthene. Another higher-yielding regime included the use of novaluron, a novel insect growth regulator (IGR) scheduled for registration in 2005 (Diamond® by Crompton Corporation). This IGR was tested against whiteflies and Lygus bugs, but in light of yield data, Lygus efficacy should be examined more closely. None of the neonicotinoids were effective against Lygus, but several proved to be promising for whitefly control. Of the neonicotinoids tested and sprayed on threshold, dinotefuran (under development by Valent) showed good activity. The performance of spiromesifin (Oberon®, a new chemistry by Bayer) was similar to dinotefuran but needing one less spray. Intruder® out-performed all whitefly treatments, requiring only two sprays to control whiteflies season-long. Both Intruder or currently used IGRs (Knack® and Courier®) proved to be very effective against whiteflies. All insecticides in this test underwent very rigorous testing under extreme Lygus and whitefly pressures.