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Cotton (Gossypium hirsutum L.) regrowth control with herbicides provides an alternative method for post-harvest destruction of cotton stalks. Field experiments were conducted in 2002 and 2003 to assess the effectiveness of different herbicide treatments for cotton regrowth control using remote sensing technology. Eight treatments (combinations of herbicides and application timings) and six treatments were evaluated in 2002 and 2003, respectively, with each experiment arranged in a randomized complete block design. Airborne multispectral imagery was acquired from the test plots in both years shortly before the state-mandated date for cotton stalk destruction. Ground reflectance spectra and plant visual ratings were also obtained from each experimental plot simultaneously. The reflectance spectra were able to detect differences in regrowth among some of the treatments. The airborne imagery permitted visual differentiation among some of the treatments. For quantitative analysis, the green, red, and near-infrared bands of the multispectral imagery and four vegetation indices derived from the three bands were used as spectral variables to compare the differences among the treatments for each experiment. Statistical analysis showed that the seven spectral variables were able to identify the differences among the treatments as detected by the ground observations. Results also indicated that the herbicide, 2,4-D (Savage), applied to shredded stalks at 1.12 kg formulation per hectare (1 lb/ac) twice within a one-month period provided excellent regrowth control. [ABSTRACT FROM AUTHOR]

A statewide monitoring program for males of bollworm (Helicoverpa zea) was conducted from May to October of 2003, surveying fifteen Texas Counties. Moths were trapped near cotton fields using pheromone, Hercon Luretape® with Zealure. Moths were collected early in the morning and assays were performed the same day. Vials were prepared in the Toxicology Laboratory, Department of Entomology at Texas A&M University, College Station, Texas and shipped as needed to Extension personnel. Vials were prepared using acetone only for controls, and cypermethrin (technical grade, 95.2% purity) at 0.3, 1, 3, 5, 10 and 30 μg/vial. One moth was placed in each vial and bioassays were evaluated after 24 h. Moths were classified as alive, dead, or "knocked-down". From Burleson County 1,814 moths were tested. Other counties in Texas participating in the monitoring program were: Castro, Hockley, Hale, Swisher and Martin Counties in the High Plains production region; Tom Green and Runnels Counties in the Southern Rolling Plains region; Ellis and Williamson Counties in the Blacklands region; Uvalde County in the Wintergarden region; Nueces and Wharton Counties in Coastal Bend region; and Hidalgo County in the Lower Rio Grande Valley. A total of 4,134 moths were tested for all areas outside Burleson County. Data from all areas in Texas was sent to Texas A&M University Toxicology laboratory and analyzed using Probit-PC, Probit and Logit Analysis and graphed using SigmaPlot. Only data from valid bioassays were analyzed. A baseline for susceptibility to cypermethrin was established from two areas in Texas with low LC50 values, Hockley County and Wharton County, these values were pooled to obtain a baseline LC50 of 0.283 μg/vial that was used to calculate relative resistance ratios for the rest of the counties. High levels of resistance were detected for Nueces, Burleson and Castro Counties; the LC50 resistance ratio as previously defined was 9 for the first two counties in July and between 4 and 10 for Castro Co., depending on the date. Bollworm populations were most susceptible to pyrethroids in 2003 in Parmer, Hale, Hockley, and Wharton Counties. [ABSTRACT FROM AUTHOR]

A field experiment was conducted to examine the usefulness of remote sensing technology for evaluating cotton (Gossypium hirsutum L.) regrowth control strategies for post-harvest destruction of cotton stalks. Ten treatments (one control and nine combinations of three herbicide mixtures and three application timings) were assigned to 30 shredded cotton plots according to a randomized complete block design in a south Texas cotton field in 2002. Ground reflectance spectra were collected on randomly selected sites from each plot 32 days after the first three of the nine herbicide treatments were applied. Meanwhile, airborne multispectral digital imagery was obtained from the field and plant regrowth was visually rated at five levels ranging from no live plants to mostly healthy plants based on ground observations. The reflectance spectra were able to separate regrowth differences among some of the treatments, though a large number of spectra were needed to achieve reliable results. The airborne imagery did not provide sufficient visual differentiation among the treatments, but the reflectance information extracted from the imagery allowed quantitative separations among the treatments. Seven spectral variables, including the green, red, and near-infrared (NIR) bands of the multispectral imagery and four vegetation indices derived from the three bands, were used to compare the differences among the treatments. Multiple comparisons showed that the green band and the four vegetation indices detected significant differences among some of the treatments as detected by the visual efficacy rating. These results indicate that remote sensing can be a useful tool for evaluating cotton regrowth control strategies. [ABSTRACT FROM AUTHOR]

Thorough cotton stalk destruction is critical and state mandated in Texas as a tool to aid in the reduction of boll weevils. Adverse weather conditions and conservation tillage often prevent immediate and complete stalk destruction. The herbicide 2,4-D amine applied at one pound formulation per acre on shredded stalks, twice during a 30 day period, was proven to be 100% effective in terminating stalks. [ABSTRACT FROM AUTHOR]

Experiments were conducted to determine the potential threat of boll weevil transport on or in cotton modules constructed in infested areas to gins in weevil-free areas. Surveys in three areas of Texas indicated that live weevils are usually present in defoliated fields just before harvest and one can expect live weevils to he packed into modules. Most weevils dispersed rapidly from untarped module surface when temperatures were warm enough for flight, but a small percentage remained at least to 24 h. Most weevils trapped on the surface under the tarp died from high temperatures . Survival of weevils inside modules was high after 1 and 3 d, but had declined dramatically by 7 d. The greatest threat of reinfestation by weevils dispersing from a module would occur when a module is constructed and transported during cool, cloudy weather, followed by warm weather favorable for flight at the gin yard. Other experiments were conducted to determine boll weevil mortality in various subprocesses in a cotton gin by introducing known numbers of weevils at various points in the system and estimating survival. We found no evidence that weevils can survive in the seed cotton to the gin stand or beyond. The greatest threat for weevil survival and escape from the gin occurs soon after entry, with chances of survival diminishing rapidly the further the weevils progress through the different ginning processes . Small numbers of live weevils can he expected to escape into the rock trap, either as free adults or in infested bolls (Brashears et al. 2003). Thus, it is important that at-risk gins either destroy the trash collected in the rock trap immediately or collect it in a container that will not permit weevil escape. Weevils protected inside unopened bolls can escape alive with the gin trash later in the cleaning process even when passed through a high-speed trash fan. If a mechanical device can he designed and installed to slightly crack open bolls as they move to the fan, this latter problem can he mitigated to a great extent. [ABSTRACT FROM AUTHOR]