@article{parkash_snider_bruce_ermanis_virk_kaur_collins_chapman_2023, title={Effects of cultivar and nitrogen application rate on lint, seed, oil, and protein yields of field-grown cotton}, ISSN={["1435-0653"]}, DOI={10.1002/csc2.20938}, abstractNote={AbstractCotton (Gossypium hirsutum L.) is not only the dominant fiber crop grown worldwide, but it is also an important source of plant‐based oil and protein. Previous research has documented a significant effect of cotton cultivar and nitrogen application individually on lint yield and seed composition, but very limited studies have evaluated the lint, seed, oil, and protein yield responses of cultivars with different seed mass and composition to a broad range of N application rates. The objective of this study was to evaluate the lint, seed, oil, and protein yield responses of cultivars with different seed mass and composition to N application rates (0–168 kg N ha−1) for field‐grown cotton. A field experiment was conducted in Tifton, GA, USA during the 2019 and 2020 growing seasons that included six cultivars and six N application rates. Cultivar significantly affected seedcotton, lint, seed, and seed reserve yields in both growing seasons. Lint yield did not follow identical trends as seed yield mainly due to cultivar variation in lint percent. Similarly, protein and oil yield were influenced by cultivar variation in seed composition. Seedcotton, seed, protein, and oil yields continually increased with increases in N application from 0 to 168 kg N ha−1, whereas for lint yield, all fertilized treatments produced comparable yields that were significantly higher (68%) than the 0 kg N ha−1 treatment. We conclude that variability in the distribution of photosynthates to fiber and seed as well as seed oil and protein composition can significantly alter trends in fiber, seed, and seed component yields in response to cultivar or N application rates for field‐grown cotton.}, journal={CROP SCIENCE}, author={Parkash, Ved and Snider, John L. and Bruce, Aaron and Ermanis, Alessandro and Virk, Gurpreet and Kaur, Navneet and Collins, Guy and Chapman, Kent D.}, year={2023}, month={Mar} }
 @article{raper_ward_rushing_brown_sandlin_norton_hutmacher_snider_fromme_dodds_et al._2023, title={Reevaluation of the degree day base 60°F concept in US cotton (Gossypium hirsutum L.) production}, volume={10}, ISSN={["1435-0645"]}, DOI={10.1002/agj2.21480}, abstractNote={AbstractCotton (Gossypium hirsutum L.) management decisions to abet early growth, fruit set, boll maturation, and harvest preparation are often facilitated by prediction of the date when critical developmental stages are reached. In the United States, growing degree days calculated with a base 60°F (DD60s) are commonly used to predict cotton development. Observations suggest development of modern cultivars differs from previously established guidelines. The objectives were to (1) reevaluate DD60s required for an early, mid‐maturing and late maturing cultivar to reach key growth stages across the US Cotton Belt; and (2) determine if predictions of growth stages are strengthened by optimizing base temperature or including an upper threshold by growth stage. During 2018 and 2019, 22 field trials were established in 10 states. Plant growth stages were monitored weekly and air temperature was computed from interpolated surface observations weighted by a physical, geographic model. Observed DD60s to reach growth stages varied slightly by cultivar and region (≤85 DD60s and ≤130 DD60s, respectively). Required DD60s to reach growth stages exceeded most published ranges. Optimization of base temperature and inclusion of an upper threshold by growth stage did not substantially decrease errors in predicting date of growth stage occurrence. The DD55 and DD55 with an upper threshold of 86°F calculations resulted in slightly lower errors in predicting date of growth stage occurrence than the DD60 calculation. Although guidelines should be updated, it is unlikely slight modification in base temperature or upper thresholds will drastically increase the predictive ability over the DD60 calculation.}, journal={AGRONOMY JOURNAL}, author={Raper, Tyson B. and Ward, Rebecca and Rushing, Cheyenne and Brown, Steve and Sandlin, Tyler and Norton, Randy and Hutmacher, Bob and Snider, John L. and Fromme, Dan and Dodds, Darrin and et al.}, year={2023}, month={Oct} }
 @article{martinez_ward_collins_nelson_2023, title={TESTING THE AGREEMENT BETWEEN A TRADITIONAL AND UAV-BASED METHOD FOR QUANTIFYING SKIPS IN SUBOPTIMAL COTTON STANDS}, volume={66}, ISSN={["2769-3287"]}, DOI={10.13031/ja.14760}, abstractNote={
						Highlights
					
					
						
							
								Agreement in the mean difference between the traditional and the UAV-based method only occurred in poor stands.
							
							
								Effects of different sampling sizes between methods were evident in mediocre-to-good stand assessments.
							
						
					
					
						Abstract. When suboptimal cotton stands occur, growers face the decision to accept or reject the stand. The replanting decision is difficult because the tradeoffs associated with replanting expenditures and reduced yields are difficult to objectively assess. Traditional methods like visual assessments and manual counts of cotton stands are commonly used to support a replanting decision. Typically, manual counts of skip size and frequency will provide more accurate assessments of the stand than visual assessments, but they are cumbersome to conduct and may not provide clear evidence that a replant is needed. Still, manual counts are popular among cotton farmers and the scientific community. Skip counts generated with the help of unmanned aerial vehicles (UAV) are less popular among cotton growers but provide more coverage and a larger sampling size across a given field. Therefore, UAVs have the potential to overcome the limitations associated with traditional methods. The motivation behind this study is to inform readers if manual methods can still be used for accurate decision-making regarding the replanting decision. More specifically, we study the interchangeability, or agreement, between a manual and a UAV-based method using Bland-Altman plots. Each method quantified skips greater than or equal to 0.91 m at different sampling sizes. Treatment plots varied in their stand counts, skip size, and skip frequency. Agreement between both methods was only found in the lowest stand treatment, where skips of large sizes were predominant. Conversely, methods disagreed in the higher stand where skips greater than or equal to 0.91 m were scarce.  Keywords: Agriculture, Altman, Bland, Drone, Gaps, Precision, Remote, Sensing, UAS.}, number={1}, journal={JOURNAL OF THE ASABE}, author={Martinez, Enrique E. Pena and Ward, Jason K. and Collins, Guy and Nelson, Natalie}, year={2023}, pages={149–153} }
 @article{chalise_snider_hand_roberts_vellidis_ermanis_collins_lacerda_cohen_pokhrel_et al._2022, title={Cultivar, irrigation management, and mepiquat chloride strategy: Effects on cotton growth, maturity, yield, and fiber quality}, volume={286}, ISSN={["1872-6852"]}, DOI={10.1016/j.fcr.2022.108633}, abstractNote={Drought negatively affects cotton growth and yield, whereas excessive irrigation can limit yield through excessive vegetative growth and poor fruit retention. Mepiquat chloride (MC) application limits plant height, improves fruit retention and hastens maturity in responsive cultivars. Thus, the objective of this study was to address the effects of cultivar, irrigation, and MC strategy on cotton growth, maturity, yield, and fiber quality. Therefore, a field study was carried out using three cultivars, three different irrigation treatments, and three different MC treatments during the 2020 and 2021 growing seasons. In both years there was an interaction between irrigation and MC management for plant height. In 2020, MC treatments hastened cutout by two to three weeks in irrigated plots but did not affect cutout date in dryland plots. 2020 and 2021 differed substantially in rainfall (347 mm and 735 mm, respectively from planting to harvest). 2020 was a dry year in which yield responded positively to irrigation and 2021 was a wet year in which yield responded negatively to irrigation. There was no effect of MC treatments or interaction between MC and any other effect on lint yield. Fiber length was reduced, whereas strength and micronaire were increased by drought stress in 2020. Increased fiber length, strength, uniformity, and micronaire were observed by MC application in both years. Therefore, we can conclude that aggressive MC management reduces vegetative growth, promotes earlier physiological maturity under well-watered conditions, and affects fiber quality, but does not necessarily interact with irrigation management to affect lint yield. • Growth and maturity responses to mepiquat chloride depend on water availability. • Mepiquat chloride hastens maturity under water replete conditions, but not dryland. • Occasionally, fiber quality was positively impacted by mepiquat chloride application. • Mepiquat chloride did not alter cotton yield response to water excess or drought.}, journal={FIELD CROPS RESEARCH}, author={Chalise, Devendra Prasad and Snider, John L. and Hand, Lavesta C. and Roberts, Phillip and Vellidis, George and Ermanis, Alessandro and Collins, Guy D. and Lacerda, Lorena N. and Cohen, Yafit and Pokhrel, Amrit and et al.}, year={2022}, month={Oct} }
 @article{liu_snider_bhattarai_collins_2022, title={Economic penalties associated with irrigation during high rainfall years in the southeastern United States}, volume={272}, ISSN={["1873-2283"]}, DOI={10.1016/j.agwat.2022.107825}, abstractNote={Although cotton is a drought-tolerant crop, irrigation is still needed to ensure productivity, even in the humid Southeastern United States. Irrigation must be carefully managed to limit unnecessary water use while ensuring maximum economic productivity. To better understand the costs and net returns of irrigation and cultivar selection, field experiments were conducted in 2016 and 2017 to compare cotton lint yield and fiber quality in dryland plots and plots irrigated using the University of Georgia checkbook method (UGA Checkbook) at a field site near Camilla, Georgia. Results showed cultivar differences in fiber quality parameters of micronaire and uniformity in 2016, but there was no cultivar difference in fiber quality in 2017. Cultivar differences were not observed in yield or net returns for both years. However, stoplight chart analysis of net returns indicated differences in cultivar selection for irrigated or dryland production. ST 6182 GLB2 would be a better option for a producer to minimize downside risk under dryland conditions, and PHY 333 WRF would be a better option under irrigated production. Results also indicated that broadly applying simplistic water balance approaches could decrease yield, water productivity, and net returns, especially in environments where rainfall is sufficient yet unpredictable. Overirrigation affected some fiber quality parameters but did not impact the overall market price for cotton. In 2016, irrigating according to the UGA Checkbook method negatively impacted yield and net returns. In 2017, irrigation did not affect yield but negatively impacted net returns. Average losses in net returns associated with excessive irrigation in these two wet years were $336 per hectare for net return over irrigation variable costs, and $645 per hectare for net return over irrigation total costs. Implementing robust, efficient irrigation strategies is necessary to achieve high cotton yields, reduce water usage, and improve economic returns.}, journal={AGRICULTURAL WATER MANAGEMENT}, author={Liu, Yangxuan and Snider, John L. and Bhattarai, Anukul and Collins, Guy}, year={2022}, month={Oct} }
 @article{joyner_cahoon_everman_collins_taylor_blythe_2022, title={HPPD-resistant cotton response to isoxaflutole applied preemergence and postemergence}, ISSN={["1550-2740"]}, DOI={10.1017/wet.2022.6}, abstractNote={AbstractStudies were conducted in 2019 and 2020 in Lewiston, NC, to determine the crop response of 4-hydroxyphenylpyrivate dioxygenase (HPPD)-resistant cotton to isoxaflutole (IFT) and other cotton herbicides as part of a cotton weed management program that included herbicides applied preemergence, early postemergence (EPOST), and mid-postemergence (MPOST). IFT was applied PRE at 105 g ha−1 alone and in various combinations with acetochlor, diuron, fluometuron, fluridone, fomesafen, pendimethalin, and pyrithiobac. EPOST treatments included IFT at 53 or 105 g ha−1 alone or in combination with glyphosate or glufosinate, or dimethenamid-P + glufosinate. Glyphosate + glufosinate was applied MPOST to all treatments except the nontreated control. Cotton injury from IFT applied PRE was minimal (0% to 3%). Injury following EPOST application of dimethenamid-P + glufosinate ranged from 3% to 5% and 6% to 9% in 2019 and 2020, respectively. In both years, injury from IFT applied PRE followed by IFT applied EPOST never exceeded injury from IFT applied PRE followed by dimethenamid-P + glufosinate. Isoxaflutole applied PRE followed by IFT applied EPOST at 105 g ha−1 resulted in 0% to 2% cotton injury, indicating that IFT can be applied either PRE or EPOST with minimal risk to cotton. Late-season cotton height and cotton lint yield were not affected by any herbicide treatment. The experimental HPPD-resistant cotton cultivar was minimally injured by IFT applied PRE and EPOST, it tolerated standard cotton herbicides, and yield loss was not observed. Given these results, HPPD-resistant cotton and IFT may be integrated into cotton weed management systems with minimal risk for cotton injury and provide an additional effective mechanism of action for managing troublesome weeds in cotton.}, journal={WEED TECHNOLOGY}, author={Joyner, Joshua D. and Cahoon, Charles W. and Everman, Wesley J. and Collins, Guy D. and Taylor, Zachary R. and Blythe, Andrew C.}, year={2022}, month={Feb} }
 @article{dorman_hopperstad_reich_majumder_kennedy_reisig_greene_reay‐jones_collins_bacheler_et al._2021, title={Landscape‐level variation in
            <i>Bt
            crops predict
            <scp>
              <i>Helicoverpa ze
            
            <scp>
              <i>a
            
            (
            <scp>Lepidoptera: Noctuidae
            ) resistance in cotton agroecosystems}, volume={77}, ISSN={1526-498X 1526-4998}, url={http://dx.doi.org/10.1002/ps.6585}, DOI={10.1002/ps.6585}, abstractNote={AbstractBACKGROUNDHelicoverpa zea (Boddie) damage to Bt cotton and maize has increased as a result of widespread Bt resistance across the USA Cotton Belt. Our objective was to link Bt crop production patterns to cotton damage through a series of spatial and temporal surveys of commercial fields to understand how Bt crop production relates to greater than expected H. zea damage to Bt cotton. To do this, we assembled longitudinal cotton damage data that spanned the Bt adoption period, collected cotton damage data since Bt resistance has been detected, and estimated local population susceptibility using replicated on‐farm studies that included all Bt pyramids marketed in cotton.RESULTSSignificant year effects of H. zea damage frequency in commercial cotton were observed throughout the Bt adoption period, with a recent damage increase after 2012. Landscape‐level Bt crop production intensity over time was positively associated with the risk of H. zea damage in two‐ and three‐toxin pyramided Bt cotton. Helicoverpa zea damage also varied across Bt toxin types in spatially replicated on‐farm studies.CONCLUSIONSLandscape‐level predictors of H. zea damage in Bt cotton can be used to identify heightened Bt resistance risk areas and serves as a model to understand factors that drive pest resistance evolution to Bt toxins in the southeastern United States. These results provide a framework for more effective insect resistance management strategies to be used in combination with conventional pest management practices that improve Bt trait durability while minimizing the environmental footprint of row crop agriculture. © 2021 Society of Chemical Industry. This article has been contributed to by US Government employees and their work is in the public domain in the USA.}, number={12}, journal={Pest Management Science}, publisher={Wiley}, author={Dorman, Seth J and Hopperstad, Kristen A and Reich, Brian J and Majumder, Suman and Kennedy, George and Reisig, Dominic D and Greene, Jeremy K and Reay‐Jones, Francis PF and Collins, Guy and Bacheler, Jack S and et al.}, year={2021}, month={Aug}, pages={5454–5462} }
 @article{morris_vann_heitman_collins_heiniger_2021, title={Maximizing soybean yield by understanding planting date, maturity group, and seeding rate interactions in North Carolina}, volume={9}, ISSN={["1435-0653"]}, DOI={10.1002/csc2.20603}, abstractNote={AbstractGrowers across theU.S. Southeast use a diversity of soybean [Glycine max (L.) Merr.] planting dates, maturity groups, and seeding rates for soybean production depending on their rotational complexity. Studies were conducted across seven North Carolina environments in 2019 and 2020 to determine the effect of planting date (mid‐March through mid‐July), maturity group (MG 2–8), and seeding rate (185,329–432,434 seeds ha–1) on soybean emergence, stand, and yield. Across environments, soybean typically emerged more quickly with later planting dates; however, there were location‐specific variations in soybean emergence due to weather conditions around the time of planting. The longest and shortest emergence periods were 26 d for soybean planted in mid‐March and 4 d for soybean planted in June and July, respectively. In the higher yielding environments, yield was maximized with MG 3–4 cultivars planted at early April planting dates and yield declined as planting was delayed. In the low yield environments, yield was maximized with late April to mid‐May planting dates, typically with MG 5–7 cultivars. There was a penalty in both yield environments to planting past mid‐May and in the low yield environments for planting before mid‐April. Across environments, yields tended to be more similar among cultivars higher than MG 3 at planting dates in June and July. The effect of seeding rate on soybean yield was variable across planting dates, maturity groups, and yield environments. Future research is needed in North Carolina to validate the planting date and maturity group interactions on yield observed in this experiment to capture more variation in weather conditions.}, journal={CROP SCIENCE}, author={Morris, Tristan C. and Vann, Rachel A. and Heitman, Josh and Collins, Guy D. and Heiniger, Ryan W.}, year={2021}, month={Sep} }
 @article{morris_vann_collins_heitman_kulesza_2021, title={Planting date and maturity group impact on soybean seed quality in the southeastern United States}, volume={11}, ISSN={["1435-0645"]}, DOI={10.1002/agj2.20913}, abstractNote={AbstractThe impacts on soybean seed quality from shifting to using earlier soybean planting dates (PDs) and earlier‐maturing varieties in the southeastern United States are not well understood. The objective of this study was to determine the impact of diverse PDs and maturity groups (MGs) on soybean protein content, oil content, seed damage, and purple seed stain. Studies were installed across seven North Carolina locations in 2019 and 2020 to determine the impact of PD (mid‐March through mid‐July) and MG (2–7) on seed quality. Protein content declined as planting was delayed for the early MGs (2–5) but was stable across PD for the later MGs (6–7). It was observed that early‐maturing varieties (MG ≤5) had a lower protein content than the later‐maturing varieties (MGs 6–7). The oil content was greater in the early MGs (MGs 2–4) compared with the later MGs (MGs 5–7), with oil content and protein content having an inverse relationship. Seed damage was greatest when planting before late April with early MGs (MGs 2–4). Less purple seed stain was found in MGs 5–7 compared with the earlier MGs across all PDs. Further research is needed to understand how to minimize seed damage and purple seed stain as producers consider shifting to an earlier production system for the associated yield benefits in North Carolina and across the southeastern United States.}, journal={AGRONOMY JOURNAL}, author={Morris, Tristan C. and Vann, Rachel A. and Collins, Guy D. and Heitman, Joshua and Kulesza, Stephanie B.}, year={2021}, month={Nov} }
 @article{hare_jordan_edmisten_leon_post_vann_dunphy_heiniger_collins_washburn_2020, title={Response of agronomic crops to planting date and double-cropping with wheat}, volume={112}, ISSN={["1435-0645"]}, url={https://doi.org/10.1002/agj2.20164}, DOI={10.1002/agj2.20164}, abstractNote={AbstractPlanting date can affect crop yield and is an important management decision for practitioners. Although wheat (Triticum aestivum L.) and soybean [Glycine max (L.) Merr.] can be effectively double‐cropped in North Carolina, if commodity prices and projected economic returns are higher for crops other than soybean, growers might consider a nontraditional, double‐crop system. Direct comparisons of major agronomic crops with different planting dates or in a double‐crop system with wheat are limited in North Carolina. Therefore, research was conducted in North Carolina from 2013 through 2017 to determine yield potential of corn (Zea mays L.), cotton (Gossypium hirsutum L.), grain sorghum [Sorghum bicolor (L.) Moench], peanut (Arachis hypogaea L.), and soybean planted at two dates within the recommended planting window for full‐season production versus planting these crops after wheat harvest. The experimental design was a split plot, with summer crop serving as the whole plot unit and planting date within a crop serving as the subplot unit. Yield of corn, cotton, grain sorghum, peanut, and soybean in full‐season production exceeded that of double‐cropping with wheat in 5, 5, 2, 4, and 5 yr out of 5 yr of the study, respectively. Estimated economic returns were generated using the 10‐yr average (2008–2017) summer crop prices with the 10‐yr average wheat price. When considering all possible combinations of years and crops (n = 25), in only 20% of the possible combinations was the economic return of the double‐cropping system greater than economic return of full‐season crop production when compared with at least one of the planting dates within the traditional planting window.}, number={3}, journal={AGRONOMY JOURNAL}, publisher={Wiley}, author={Hare, Andrew T. and Jordan, David L. and Edmisten, Keith L. and Leon, Ramon G. and Post, Angela R. and Vann, Rachel and Dunphy, E. James and Heiniger, Ronnie and Collins, Guy and Washburn, Derek}, year={2020}, pages={1972–1980} }
 @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{byrd_collins_barentine_snider_culpepper_roberts_porter_whitaker_2019, title={Tillage and Irrigation Impact on Early and Late Maturing Cotton Cultivars}, volume={111}, ISSN={["1435-0645"]}, DOI={10.2134/agronj2017.11.0643}, abstractNote={Core Ideas
There was little interaction between tillage and irrigation on agronomic parameters.Excessive rainfall minimized agronomic benefits of the rolled rye cover crop.Continuous experiments are likely optimal to properly evaluate cover crop systems.
Concerns surrounding agricultural water use have increased interest in investigating more efficient cotton (Gossypium hirsutum L.) production practices. A study was conducted to determine potential water savings from using a conservation tillage system employing a cereal rye (Secale cereale L.) cover crop. The performance of early and late maturing cotton cultivars was assessed in two tillage systems, conventional or strip tillage with a rye cover crop, under various irrigation levels (100, 75, and 50% of University of Georgia recommendations, and non‐irrigated) to determine the effect of crop growth, development, and yield in Camilla, GA (2013 and 2014), Moultrie, GA (2014), and Vienna, GA (2014). At Camilla, increases in irrigation typically benefited the cotton crop regardless of tillage treatment; however, there was little difference between the two highest irrigation treatments, suggesting that application rates <100% recommendations could result in water savings. During 2013, excessive rainfall resulted in minimal soil moisturedifferences; subsequently, cotton growth, development, and yield were negatively impacted under strip tillage compared with conventional. Although almost half the rainfall was received in 2014 compared with 2013, and the conservation tillage system benefited crop growth and development, no yield differences were observed. At Moultrie and Vienna, either no difference between tillage systems or only benefits to crop growth and development in the conventional tillage system occurred. Results illustrate that the potential impact of cover crops is highly dependent on environmental conditions and is likely minimal under slight to moderate water deficit conditions, but can be detrimental when excessive rainfall occurs.}, number={4}, journal={AGRONOMY JOURNAL}, author={Byrd, Seth A. and Collins, Guy D. and Barentine, Ronnie M. and Snider, John L. and Culpepper, A. Stanley and Roberts, Phillip M. and Porter, Wesley M. and Whitaker, Jared R.}, year={2019}, pages={1620–1633} }
 @article{byrd_collins_culpepper_dodds_edmisten_wright_morgan_baumann_dotray_manuchehri_et al._2016, title={Cotton Stage of Growth Determines Sensitivity to 2,4-D}, volume={30}, ISSN={["1550-2740"]}, DOI={10.1614/wt-d-15-00191.1}, abstractNote={The anticipated release of EnlistTM cotton, corn, and soybean cultivars likely will increase the use of 2,4-D, raising concerns over potential injury to susceptible cotton. An experiment was conducted at 12 locations over 2013 and 2014 to determine the impact of 2,4-D at rates simulating drift (2 g ae ha−1) and tank contamination (40 g ae ha−1) on cotton during six different growth stages. Growth stages at application included four leaf (4-lf), nine leaf (9-lf), first bloom (FB), FB + 2 wk, FB + 4 wk, and FB + 6 wk. Locations were grouped according to percent yield loss compared to the nontreated check (NTC), with group I having the least yield loss and group III having the most. Epinasty from 2,4-D was more pronounced with applications during vegetative growth stages. Importantly, yield loss did not correlate with visual symptomology, but more closely followed effects on boll number. The contamination rate at 9-lf, FB, or FB + 2 wk had the greatest effect across locations, reducing the number of bolls per plant when compared to the NTC, with no effect when applied at FB + 4 wk or later. A reduction of boll number was not detectable with the drift rate except in group III when applied at the FB stage. Yield was influenced by 2,4-D rate and stage of cotton growth. Over all locations, loss in yield of greater than 20% occurred at 5 of 12 locations when the drift rate was applied between 4-lf and FB + 2 wk (highest impact at FB). For the contamination rate, yield loss was observed at all 12 locations; averaged over these locations yield loss ranged from 7 to 66% across all growth stages. Results suggest the greatest yield impact from 2,4-D occurs between 9-lf and FB + 2 wk, and the level of impact is influenced by 2,4-D rate, crop growth stage, and environmental conditions.}, number={3}, journal={WEED TECHNOLOGY}, author={Byrd, Seth A. and Collins, Guy D. and Culpepper, A. Stanley and Dodds, Darrin M. and Edmisten, Keith L. and Wright, David L. and Morgan, Gaylon D. and Baumann, Paul A. and Dotray, Peter A. and Manuchehri, Misha R. and et al.}, year={2016}, pages={601–610} }
 @article{foote_edmisten_wells_collins_roberson_jordan_fisher_2016, title={Influence of nitrogen and mepiquat chloride on cotton canopy reflectance measurements}, volume={20}, number={1}, journal={Journal of Cotton Science}, author={Foote, W. and Edmisten, K. and Wells, R. and Collins, G. and Roberson, G. and Jordan, D. and Fisher, L.}, year={2016}, pages={1–7} }
 @article{chastain_snider_collins_perry_whitaker_byrd_oosterhuis_porter_2016, title={Irrigation Scheduling Using Predawn Leaf Water Potential Improves Water Productivity in Drip-Irrigated Cotton}, volume={56}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2016.01.0009}, abstractNote={To address the effectiveness of predawn leaf water potential in plant‐based irrigation scheduling, Gossypium hirsutum L. plants were grown under fully irrigated and dryland conditions and under three predawn water potential (ΨPD) thresholds (−0.5, −0.7, and −0.9 MPa). Measurements included ΨPD, plant height, mainstem node number, lint yield, water productivity, and continuous crop canopy temperature. We found that ΨPD produced similar yields to current practices, while decreasing overall water use from 7 to 31%, depending on rainfall levels and the treatment utilized. When considered across both years of the study (2013 and 2014), using a −0.5‐MPa ΨPD irrigation threshold consistently resulted in less irrigation applied than the checkbook method and maximum water productivity and lint yield. Using a well‐watered baseline developed in 2013 for canopy temperature versus vapor pressure deficit, we calculated a crop water stress index (CWSI) that exhibited a very strong, nonlinear relationship with season average ΨPD values between approximately −0.4 and −0.7 MPa (r2 = 0.81). A strong, nonlinear relationship was also seen between CWSI and lint yield (r2 = 0.81). Predawn water potential appears to be an effective means of determining the need for irrigation in cotton, and in the current study, yield and water productivity were maximized at a season‐long average ΨPD threshold of −0.5 MPa. Furthermore, when calibrated using ΨPD–based irrigation triggers, canopy‐temperature derived CWSI appears to be a promising tool for future automated plant‐based irrigation scheduling in the southeastern United States.}, number={6}, journal={CROP SCIENCE}, author={Chastain, Daryl R. and Snider, John L. and Collins, Guy D. and Perry, Calvin D. and Whitaker, Jared and Byrd, Seth A. and Oosterhuis, Derrick M. and Porter, Wesley M.}, year={2016}, pages={3185–3195} }
 @article{chastain_snider_choinski_collins_perry_whitaker_grey_sorensen_iersel_byrd_et al._2016, title={Leaf ontogeny strongly influences photosynthetic tolerance to drought and high temperature in Gossypium hirsutum}, volume={199}, ISSN={["1618-1328"]}, DOI={10.1016/j.jplph.2016.05.003}, abstractNote={Temperature and drought are major abiotic limitations to crop productivity worldwide. While abiotic stress physiology research has focused primarily on fully expanded leaves, no studies have investigated photosynthetic tolerance to concurrent drought and high temperature during leaf ontogeny. To address this, Gossypium hirsutum plants were exposed to five irrigation treatments, and two different leaf stages were sampled on three dates during an abnormally dry summer. Early in the growing season, ontogenic PSII heat tolerance differences were observed. Photosystem II was more thermotolerant in young leaves than mature leaves. Later in the growing season, no decline in young leaf net photosynthesis (PN) was observed as leaf temperature increased from 31 to 37 °C, as average midday leaf water potential (ΨMD) declined from −1.25 to −2.03 MPa. In contrast, mature leaf PN declined 66% under the same conditions. Stomatal conductance (gs) accounted for 84–98% of variability in leaf temperature, and gs was strongly associated with ΨMD in mature leaves but not in young leaves. We conclude that young leaves are more photosynthetically tolerant to heat and drought than mature leaves. Elucidating the mechanisms causing these ontogenic differences will likely help mitigate the negative impacts of abiotic stress in the future.}, journal={JOURNAL OF PLANT PHYSIOLOGY}, author={Chastain, Daryl R. and Snider, John L. and Choinski, John S. and Collins, Guy D. and Perry, Calvin D. and Whitaker, Jared and Grey, Timothy L. and Sorensen, Ronald B. and Iersel, Marc and Byrd, Seth A. and et al.}, year={2016}, month={Jul}, pages={18–28} }
 @article{byrd_collins_edmisten_roberts_snider_spivey_whitaker_porter_culpepper_2016, title={Leaf pubescence and defoliation strategy influence on cotton defoliation and fiber quality}, volume={20}, number={4}, journal={Journal of Cotton Science}, author={Byrd, S. A. and Collins, G. D. and Edmisten, K. L. and Roberts, P. M. and Snider, J. L. and Spivey, T. A. and Whitaker, J. R. and Porter, W. M. and Culpepper, A. S.}, year={2016}, pages={280–293} }
 @article{snider_collins_whitaker_chapman_horn_2016, title={The impact of seed size and chemical composition on seedling vigor, yield, and fiber quality of cotton in five production environments}, volume={193}, ISSN={["1872-6852"]}, DOI={10.1016/j.fcr.2016.05.002}, abstractNote={Seed mass and oil content of the quiescent cotton seed are positively associated with seedling vigor. In contrast, seed size has been negatively associated with lint yield due to selection for cultivars with greater lint percent. The current study addressed the hypothesis that planting seed mass and total oil + protein calorie content of the quiescent cotton seed would be strongly predictive of seedling vigor across most field conditions and that the impact of seed traits on yield would be dependent upon yield environment. When considered in each yield environment, seedling vigor was positively associated with seed size and the total oil + protein calorie content per seed in four out five environments tested. Regression analysis of cultivar mean oil + protein kcal content per seed versus seedling vigor across all environments indicated a strong, positive relationship between the two parameters (r2 = 0.65). Although lint percent was positively correlated with lint yield in every environment, planting seed mass and calorie content were not correlated with lint yield in four of the five environments tested or when cultivar means for lint yield and seed characteristics were averaged across all environments. Thus, it is concluded that individual planting seed mass and total energy content for oil + protein are strong predictors of early seedling vigor. Furthermore, selecting commercially available cultivars with characteristics indicative of seedling vigor does not appear to limit lint yield in most environments tested.}, journal={FIELD CROPS RESEARCH}, author={Snider, John L. and Collins, Guy D. and Whitaker, Jared and Chapman, Kent D. and Horn, Patrick}, year={2016}, month={Jul}, pages={186–195} }
 @article{snider_chastain_meeks_collins_sorensen_byrd_perry_2015, title={Predawn respiration rates during flowering are highly predictive of yield response in Gossypium hirsutum when yield variability is water-induced}, volume={183}, ISSN={["1618-1328"]}, DOI={10.1016/j.jplph.2015.06.003}, abstractNote={Respiratory carbon evolution by leaves under abiotic stress is implicated as a major limitation to crop productivity; however, respiration rates of fully expanded leaves are positively associated with plant growth rates. Given the substantial sensitivity of plant growth to drought, it was hypothesized that predawn respiration rates (RPD) would be (1) more sensitive to drought than photosynthetic processes and (2) highly predictive of water-induced yield variability in Gossypium hirsutum. Two studies (at Tifton and Camilla Georgia) addressed these hypotheses. At Tifton, drought was imposed beginning at the onset of flowering (first flower) and continuing for three weeks (peak bloom) followed by a recovery period, and predawn water potential (ΨPD), RPD, net photosynthesis (AN) and maximum quantum yield of photosystem II (Fv/Fm) were measured throughout the study period. At Camilla, plants were exposed to five different irrigation regimes throughout the growing season, and average ΨPD and RPD were determined between first flower and peak bloom for all treatments. For both sites, fiber yield was assessed at crop maturity. The relationships between ΨPD, RPD and yield were assessed via non-linear regression. It was concluded for field-grown G. hirsutum that (1) RPD is exceptionally sensitive to progressive drought (more so than AN or Fv/Fm) and (2) average RPD from first flower to peak bloom is highly predictive of water-induced yield variability.}, journal={JOURNAL OF PLANT PHYSIOLOGY}, author={Snider, John L. and Chastain, Daryl R. and Meeks, Calvin D. and Collins, Guy D. and Sorensen, Ronald B. and Byrd, Seth A. and Perry, Calvin D.}, year={2015}, month={Jul}, pages={114–120} }
 @article{christ_webster_collins_toma_byrd_2015, title={Using precipitation forecasts to irrigate cotton}, volume={19}, number={3}, journal={Journal of Cotton Science}, author={Christ, E. H. and Webster, P. J. and Collins, G. D. and Toma, V. E. and Byrd, S. A.}, year={2015}, pages={351–358} }
 @article{stewart_edmisten_wells_collins_2007, title={Measuring canopy coverage with digital imaging}, volume={38}, ISSN={["0010-3624"]}, DOI={10.1080/00103620701277718}, abstractNote={Abstract Sampling plant canopies for their ability to intercept sunlight has traditionally been done with destructive or time‐consuming methods. Although nondestructive methods are available, they are either time consuming or subject to large variation. A commercially available software was utilized to analyze digital images of a cotton (Gossypium hirsutum L.) canopy in an effort to quantify canopy coverage. Digital images were obtained from a vertical perspective using a stationary camera stand. Images were analyzed using Adobe Photoshop 4.0 (Adobe Systems, Inc., Seattle, WA) software. Using functions within the software, plant material in the image was separated from the soil and converted to black. The soil surface was converted to white. The resulting black and white image was analyzed with Javascript software developed at North Carolina State University that counts the black and white pixels in each image. The resulting percentage of black pixels in the image was termed percent ground cover for the canopy. Percent ground cover was well correlated with leaf area index (LAI) over a low range of LAI with r2=0.74. This method provides a reasonable estimation of canopy coverage and proved to be a simple and efficient method of sampling a plant canopy. As image processing software becomes more refined, this and other techniques will become powerful tools for plant science research.}, number={7-8}, journal={COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS}, author={Stewart, Alexander M. and Edmisten, Keith L. and Wells, Randy and Collins, Guy D.}, year={2007}, pages={895–902} }