Browsing by Author "Baughman, Todd A."
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Item Comparison of glufosinate-tolerant, glyphosate-tolerant, and non-transgenic cotton weed control systems(2005-05) McCormick, Kenneth M.; Keeling, Wayne; Dotray, Peter A.; Boman, Randal K.; Segarra, Eduardo; Baughman, Todd A.Two irrigated and two dryland studies were conducted in 2003 and 2004 to compare net returns between glufosinate- and glyphosate-tolerant, and conventional cotton weed management systems. Herbicides within each weed control system were sprayed as needed based on recommended label rates and limitations, and were made independent of the weed control inputs within other systems. Weed control system costs were calculated using seed costs including technology fees, herbicide and application costs, and mechanical inputs, and lint yields were determined. The net returns above weed control system costs in 2003 with the glyphosate-tolerant system was $1,514/ha in the Lubbock irrigated study, while the glufosinate-tolerant system and conventional system were $1,131 and $889/ha, respectively. The net returns above weed control system costs were similar and ranged from $780 to $854/ha in 2004. Net returns above weed control system costs were similar for all three systems when averaged over years at the Lubbock dryland location and in 2003 at a second dryland location near Lockett. The glufosinate- and glyphosate-tolerant systems had similar net returns when averaged over years at an irrigated study near New Deal, and were greater than the conventional system. Unlike the other three trials, the conventional weed control system generated greater net returns above weed control system costs at Lockett in 2004 compared to the glyphosate-tolerant system. The glyphosate-tolerant system generally required less input to maintain effective weed control compared to the glufosinate-tolerant system, while the glufosinate-tolerant system required less input compared to the conventional system.Item Effects of Fungicides, Time of Application, and Application Method on Control of Sclerotinia Blight in Peanut(2015) Woodward, Jason E. (TTU); Russell, Scott A.; Baring, Michael R.; Cason, John M.; Baughman, Todd A.Field studies were conducted from 2007 to 2010 to evaluate the response of peanut cultivars to different fungicides, application timings, and methods. Overall, fungicides reduced Sclerotinia blight incidence and increased pod yields when applied to susceptible and partially resistant cultivars. Disease suppression was greater when full fungicide rates were applied preventatively; however, yields between fungicide treated plots were similar. Lower levels of disease and higher yields were achieved with the partially resistant cultivar Tamrun OL07 compared to the susceptible cultivars Flavor Runner 458 and Tamrun OL 02. Despite possessing improved resistance Tamrun OL07 responded to all fungicide applications. While similar levels of disease control were achieved with broadcast or banded applications made during the day or at night, the yield response for the different application methods was inconsistent among years. A negative relationship (slope = -73.8; R2 = 0.73; P < 0.01) was observed between final disease incidence ratings and yield data from studies where a fungicide response was observed. These studies suggest that both boscalid and fluazinam are effective at controlling Sclerotinia blight in peanuts. Alternative management strategies such as nighttime and banded applications could allow for lower fungicide rates to be used; however, additional studies are warranted.Item Management of glyphosate-resistant Palmer amaranth in West Texas(2019-05) Merchant, Rand Michael; Dotray, Peter A.; Keeling, Wayne; Baughman, Todd A.; Ritchie, Glen L.; Ritz, RudyGlyphosate-resistant Palmer amaranth is a relatively new and significant threat to cotton production in West Texas. Field trials were conducted from 2013 to 2015 in locations around Lubbock, TX to determine Palmer amaranth response to existing residual herbicide options in cotton. This work showed that for Palmer amaranth to be controlled at least 90%, multiple applications of residual herbicides throughout the growing season were necessary. These included the use of preplant, at-plant, and postemergence residual herbicide options used in conjunction with effective postemergence-topical herbicides. Tillage is also an important part of Palmer amaranth management and the use of tillage practices improved Palmer amaranth control over herbicide use alone. A longitudinal survey tool was also implemented in order to track changes in grower weed management practices as glyphosate-resistance spread. This survey tool showed that grower awareness of glyphosate-resistance increased over a four year period and that management strategies changed to counter the growing threat.Item Site-specific weed management in cotton and peanut using WebHADSS(2007-05) Ford, Adam J.; Dotray, Peter A.; Keeling, Wayne; Galyean, Michael L.; Baughman, Todd A.Current commercial sprayers apply herbicides uniformly across the entire field, even though extensive research has shown that weeds are patchy in distribution. There is a commercially available weed-sensing sprayer (WSS) that can detect and treat weeds, but cannot differentiate between weed and crop plants. Therefore, the WSS sprayer can currently be used for weed control only in the area between crop rows. In addition to WSS’s, computer-based decision support systems have been developed to assist producers with herbicide recommendations based on various inputs. The objectives were to (1) evaluate weed control and herbicide use in a site-specific management system compared to a conventional broadcast system, (2) utilize and modify a decision support system (WebHADSSTM), and (3) evaluate weed population changes over time.Item Weed management in Roundup Ready Flex cotton(2005-05) Joy, Brandon L.; Keeling, Wayne; Dotray, Peter A.; Elam, Emmett W.; Baughman, Todd A.; Boman, Randal K.The Texas High Plains continues to plant a large number of hectares to Roundup Ready cotton varieties because effective control of a wide range of annual and perennial weeds is achieved with glyphosate. The current Roundup Ready technologies allow postemergence over-the-top (POST) applications up to the 5-leaf cotton growth stage. This application window is often narrow due to wet or windy conditions that make it difficult to treat large acreages. The development of Roundup Ready Flex varieties with increased tolerance will allow POST applications beyond the 5-leaf cotton growth stage with the additional benefit of higher glyphosate rates for improved control of more difficult-to-control weeds. Tolerance tests on Roundup Ready Flex lines continue to exhibit excellent tolerance to POST glyphosate applications up to the 14-leaf cotton growth stage at rates 2 to 3 times higher than the currently used rate in Roundup Ready cotton. Field experiments were conducted in 2003 and 2004 at the Texas Agricultural Experiment Station near Lubbock to evaluate glyphosate rates and timings for optimum control of Palmer amaranth (Amaranthus palmeri), devil’s-claw (Proboscidea louisianica), ivyleaf morningglory (Ipomoea hederaceae), and silverleaf nightshade (Solanum elaeagnifolium) in Roundup Ready Flex cotton. Glyphosate was applied at 0.84 and 1.68 kg ae/ha. Treatments based on cotton growth stage were compared to as-needed treatments based on weed population and size. Trifluralin at 0.84 kg ai/ha was applied preplant incorporated (PPI) to all test areas. Another experiment was conducted in 2004 to evaluate timing of residual herbicide use in conjunction with glyphosate to control Palmer amaranth and devil’s-claw. Glyphosate was applied at 0.84 kg/ha alone or following trifluralin PPI at 0.84 kg/ha, or in combination with metolachlor at 1.12 kg ai/ha POST or pyrithiobac at 0.04 kg ai/ha POST. Excellent Palmer amaranth, devil’s-claw, and silverleaf nightshade control (> 90%) was achieved with POST treatments based either on cotton growth stage or as needed applications in both years. For these weeds, effective control was achieved with 0.84 kg/ha treatments, with no benefit from higher glyphosate rates. In both years ivyleaf morningglory control was improved with an increase in glyphosate rate to 1.68 kg/ha. In 2003, effective ivyleaf morningglory control was achieved with four POST applications applied as needed beginning at the 2-leaf cotton growth stage, with the last treatment applied at the 20-leaf cotton growth stage. By delaying the first application, only three POST treatments were required when applied at the 1.68 kg/ha rate to achieve similar control. In 2004 with increased rainfall and weed pressure, five applications of glyphosate at 1.68 kg/ha were required for effective control (> 90%). In 2004 the addition of a soil residual herbicide (trifluralin PPI, metolachlor or pyrithiobac POST) reduced the number of in-season glyphosate applications by one (from three to two) for season-long Palmer amaranth and devil’s-claw control.