Evaluation of PGR properties of TRIMAX in cotton
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.
Advisor:Cothren, J. Tom; Binzel, Marla; Lemon, Robert G.
School:Texas A&M University
School Location:USA - Texas
Source Type:Master's Thesis
Keywords:cotton trimax pgr
Date of Publication:08/01/2005