Evaluation of PGR properties of TRIMAX in cotton
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Pesticides comprise a large portion of production inputs in cotton. Reducing or enhancing their efficacy presents an avenue to increase profit. Pesticides containing both insecticidal and growth enhancing properties may be a viable option to increased profitability. In cotton (Gossypium hirsutum L.), early season applications of some insecticides have shown effects similar to those of plant growth regulators (PGRs). TRIMAX?? (imidacloprid) is one of these purported PGR insecticides. TRIMAX?? and Centric?? 40WG (thiamethoxam), both nitroguanidine insecticides, have properties that may exhibit PGR activity. A two - year field study was conducted at the Texas A&M Agricultural Experiment Station in Burleson County, Texas to assess the physiological effects of Centric?? 40WG and TRIMAX?? on cotton. The statistical design consisted of a randomized complete block with four replications. Treatments consisted of each insecticide being applied one, two, and three times at the 5- leaf stage, 5- leaf stage plus 10 days after initial treatment (DAIT), and 5-leaf stage plus 10 DAIT plus 20 DAIT. Rates consisted of TRIMAX?? and Centric?? 40WG being applied at 0.020 and 0.017 L/ha, respectively. Data was collected for plant height, total number of nodes, biomass partitioning, photosynthetic rate, midseason plant mapping, end of season box- mapping, yield, and fiber quality analysis. No significant differences in lint yield were observed among any of the insecticide PGR treatments. There was a general trend for numeric decreases in lint yield with each additional insecticide application for both chemistries, with the exception of TRIMAX?? at three applications in 2004. No significant differences were detected in any of the growth parameters that were measured (height, total nodes, biomass partitioning, and leaf area). Numerical differences resulted in trends, but rate responses did not follow any logical pattern. Numerous trends and rate responses were also observed in the Absolute and Relative Growth Rates, and photosynthetic rates, but no significant differences were evident. In general, as more insecticide was applied, the photosynthetic rates decreased along with lint yield. Based on the parameters investigated during the course of this two-year study, there is no conclusive evidence that supports TRIMAX?? or Centric?? 40WG as being growth and or yield enhancers in cotton.
McGuire, Cy Christopher (2005). Evaluation of PGR properties of TRIMAX in cotton. Master's thesis, Texas A&M University. Texas A&M University. Available electronically from