@article{braswell_reisig_sorenson_collins_2019, title={Development and Dispersal of Helicoverpa zea (Lepidoptera: Noctuidae) on Non-Bt and Bt Pyramided Cotton}, volume={48}, ISSN={0046-225X 1938-2936}, url={http://dx.doi.org/10.1093/ee/nvz006}, DOI={10.1093/ee/nvz006}, abstractNote={Abstract Bollworm (Helicoverpa zea Boddie) (Lepidoptera: Noctuidae) can cause economic losses in both non-Bt and Bt cotton. Larvae modify their behavior in the presence of Bt by moving away from terminals faster in Bt cotton compared to non-Bt cotton and avoiding Bt-treated diets. Our objectives were to understand differences in bollworm egg and larvae populations within, and dispersal away from, non-Bt and Bt pyramided-toxin cotton. We conducted small plot experiments in 2016 and 2017 to monitor on-plant egg and larval numbers, and off-plant dispersal of larvae, from non-Bt and different Bt toxin pyramided cotton. Bollworm adults preferred to oviposit in most Bt toxin pyramids compared to non-Bt; this was likely unrelated to detection of Bt by adults, but rather density-dependent aversion from high larval populations. First instar numbers were similar in all non-Bt/Bt toxin pyramids and dispersed at a similar rate. Second through fifth instar numbers were higher in non-Bt than Bt toxin pyramids but dispersed equally from all non-Bt/Bt toxin pyramids, regardless of Bt pyramid type. Development times of larvae were often slower in Bt toxin pyramids compared to non-Bt. Fifth instars were found in, and dispersing from, Bt toxin pyramids containing Vip3A, raising concerns of resistance development. Furthermore, differences in oviposition rate among non-Bt/Bt toxin pyramids and slowed development rate of larvae on Bt varieties could create inconsistencies in generation times emerging from Bt and non-Bt hosts, which could contribute to resistance development.}, number={2}, journal={Environmental Entomology}, publisher={Oxford University Press (OUP)}, author={Braswell, Lewis R and Reisig, Dominic D and Sorenson, Clyde E and Collins, Guy D}, year={2019}, month={Jan}, pages={465–477} } @article{braswell_reisig_sorenson_collins_2019, title={Helicoverpa zea (Lepidoptera: Noctuidae) Oviposition and Larval Vertical Distribution in Bt Cotton Under Different Levels of Nitrogen and Irrigation}, volume={112}, ISSN={0022-0493 1938-291X}, url={http://dx.doi.org/10.1093/jee/toz023}, DOI={10.1093/jee/toz023}, abstractNote={In some Bt cotton (Gossypium hirsutum L.) varieties, bollworm (Helicoverpa zea Boddie) larval behavior differs from non-Bt varieties. Laboratory assays indicate bollworm larvae can detect Bt proteins, which may cause behavioral differences. Plant stress from factors including fertility and water availability causes changes in plant physiology and Bt expression. Our objective was to determine whether nitrogen and irrigation influenced bollworm behavior in Bt cotton by recording the vertical distribution of eggs and larvae over time. We conducted small plot experiments with Cry1Ac + Cry1F cotton in 2016 and 2017 with three nitrogen rates, along with irrigated and nonirrigated treatments during 2017. Bollworm locations were determined by in-field examination of 10-20 cotton plants per plot over 6-8 wk. The location of each egg and larva was recorded by node, with instar estimation of each larva. Oviposition was higher in in plots receiving nitrogen; first and second instars were also more common in plots receiving nitrogen or irrigation, whereas older instars had similar numbers among treatments. Oviposition was more evenly distributed throughout the canopy earlier in the sampling period than during later weeks, with more eggs in the top third of the canopy in only three of 14-wk. Early instars were also evenly distributed throughout the canopy. Later, instars moved to the middle portions of the canopy, away from bottom nodes, and did not move toward the terminal. Understanding bollworm behavior can inform both crop scouting and resistance management decisions.}, number={3}, journal={Journal of Economic Entomology}, publisher={Oxford University Press (OUP)}, author={Braswell, Lewis R and Reisig, Dominic D and Sorenson, Clyde E and Collins, Guy D}, year={2019}, month={Feb}, pages={1237–1250} } @article{braswell_reisig_sorenson_collins_2019, title={Helicoverpa zea (Lepidoptera: Noctuidae) Preference for Plant Structures, and Their Location, Within Bt Cotton Under Different Nitrogen and Irrigation Regimes}, volume={112}, ISSN={0022-0493 1938-291X}, url={http://dx.doi.org/10.1093/jee/toz105}, DOI={10.1093/jee/toz105}, abstractNote={Abstract Helicoverpa zea Boddie is a common economic pest of cotton (Gossypium hirsutum L.), including transgenic cotton varieties that express Bacillus thuringiensis (Bt). Helicoverpa zea oviposition is similar in Bt and non-Bt cotton, but behavior of H. zea larvae can be different in the presence of Bt, with neonates moving away from terminals faster in single-toxin Bt than non-Bt cotton or avoiding Bt-treated diet in the lab. We quantified H. zea oviposition and larval distribution on structures within cotton plants in small plot experiments of Cry1Ac + Cry1F cotton for 2 yr under different irrigation and nitrogen treatments. More eggs were oviposited on plants receiving nitrogen application during 2016 and on leaves in the top section of irrigated plants during 2017, but other treatment effects on eggs or larvae were minimal. Helicoverpa zea eggs were most common on leaves in the top third of plants at position zero and middle section of cotton plants throughout the season, but some oviposition occurred on fruiting structures as well. First and second instars were more common on squares in the top section of plants during 2016 and bolls in the middle and lower sections during 2017 due to oviposition lower in the canopy during 2017. During both years, third through fifth instars were more common on bolls in the middle and lower section of plants closer to the main stem. These findings have resistance management implications as extended larval feeding on bolls could optimize nutrition, decrease Bt susceptibility, and potentially influence behavioral resistance.}, number={4}, journal={Journal of Economic Entomology}, publisher={Oxford University Press (OUP)}, author={Braswell, Lewis R and Reisig, Dominic D and Sorenson, Clyde E and Collins, Guy D}, year={2019}, month={Apr}, pages={1741–1751} } @article{braswell_cahoon_seagroves_jordan_york_2016, title={Integrating fluridone into a glufosinate-based program for Palmer amaranth control in cotton}, volume={20}, number={4}, journal={Journal of Cotton Science}, author={Braswell, L. R. and Cahoon, C. W. and Seagroves, R. W. and Jordan, D. L. and York, A. C.}, year={2016}, pages={394–402} } @article{soltani_dille_burke_everman_vangessel_davis_sikkema_2016, title={Potential Corn Yield Losses from Weeds in North America}, volume={30}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-16-00046.1}, abstractNote={Crop losses from weed interference have a significant effect on net returns for producers. Herein, potential corn yield loss because of weed interference across the primary corn-producing regions of the United States and Canada are documented. Yield-loss estimates were determined from comparative, quantitative observations of corn yields between nontreated and treatments providing greater than 95% weed control in studies conducted from 2007 to 2013. Researchers from each state and province provided data from replicated, small-plot studies from at least 3 and up to 10 individual comparisons per year, which were then averaged within a year, and then averaged over the seven years. The resulting percent yield-loss values were used to determine potential total corn yield loss in t ha−1 and bu acre−1 based on average corn yield for each state or province, as well as corn commodity price for each year as summarized by USDA-NASS (2014) and Statistics Canada (2015). Averaged across the seven years, weed interference in corn in the United States and Canada caused an average of 50% yield loss, which equates to a loss of 148 million tonnes of corn valued at over U.S.$26.7 billion annually.}, number={4}, journal={WEED TECHNOLOGY}, author={Soltani, Nader and Dille, J. Anita and Burke, Ian C. and Everman, Wesley J. and VanGessel, Mark J. and Davis, Vince M. and Sikkema, Peter H.}, year={2016}, pages={979–984} } @article{braswell_york_jordan_seagroves_2015, title={Effect of diuron and fluometuron on grain sorghum and soybean as replacement crops following a cotton stand failure}, volume={19}, number={3}, journal={Journal of Cotton Science}, author={Braswell, L. R. and York, A. C. and Jordan, D. L. and Seagroves, R. W.}, year={2015}, pages={613–621} } @article{cahoon_york_jordan_everman_seagroves_braswell_jennings_2015, title={Weed Control in Cotton by Combinations of Microencapsulated Acetochlor and Various Residual Herbicides Applied Preemergence}, volume={29}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-15-00061.1}, abstractNote={Residual herbicides are routinely recommended to aid in control of glyphosate-resistant (GR) Palmer amaranth in cotton. Acetochlor, a chloroacetamide herbicide, applied PRE, controls Palmer amaranth. A microencapsulated (ME) formulation of acetochlor is now registered for PRE application in cotton. Field research was conducted in North Carolina to evaluate cotton tolerance and Palmer amaranth control by acetochlor ME alone and in various combinations. Treatments, applied PRE, consisted of acetochlor ME, pendimethalin, or no herbicide arranged factorially with diuron, fluometuron, fomesafen, diuron plus fomesafen, and no herbicide. The PRE herbicides were followed by glufosinate applied twice POST and diuron plus MSMA directed at layby. Acetochlor ME was less injurious to cotton than pendimethalin. Acetochlor ME alone or in combination with other herbicides reduced early season cotton growth 5 to 8%, whereas pendimethalin alone or in combinations injured cotton 11 to 13%. Early season injury was transitory, and by 65 to 84 d after PRE treatment, injury was no longer noticeable. Before the first POST application of glufosinate, acetochlor ME and pendimethalin controlled Palmer amaranth 84 and 64%, respectively. Control by acetochlor ME was similar to control by diuron plus fomesafen and greater than control by diuron, fluometuron, or fomesafen alone. Greater than 90% control was obtained with acetochlor ME mixed with diuron or fomesafen. Palmer amaranth control was similar with acetochlor ME plus a full or reduced rate of fomesafen. Acetochlor ME controlled large crabgrass and goosegrass at 91 and 100% compared with control at 83 and 91%, respectively, by pendimethalin. Following glufosinate, applied twice POST, and diuron plus MSMA, at layby, 96 to 99% control was obtained late in the season by all treatments, and no differences among herbicide treatments were noted for cotton yield. This research demonstrated that acetochlor ME can be safely and effectively used in cotton weed management programs.}, number={4}, journal={WEED TECHNOLOGY}, author={Cahoon, Charles W. and York, Alan C. and Jordan, David L. and Everman, Wesley J. and Seagroves, Richard W. and Braswell, Lewis R. and Jennings, Katherine M.}, year={2015}, pages={740–750} }