• Susceptibility of Arizona Pink Bollworm to Cry1Ac Following Six Years of Intensive Use of Transgenic Bt Cotton in Arizona

      Denney, Timothy J.; Shriver, Laura; Sims, Maria A.; Holley, Danny; Carrière, Yves; Tabashnik, Bruce; Antilla, Larry; Whitlow, Mike; Department of Entomology, The University of Arizona, Tucson, AZ; Arizona Cotton Research and Protection Council, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      We summarize information on the performance of Bt cotton against pink bollworm (PBW), Pectinophora gossypiella, in Arizona following six years of use of this new technology. Monitoring of PBW susceptibility to Bt toxin Cry1Ac was conducted annually since 1997 by collecting insects from ten to 17 cotton fields, culturing strains in the laboratory, and measuring susceptibility to Cry1Ac in diet-incorporation bioassays. Based on survival in discriminating concentration bioassays of 10 μg Cry1Ac/ml of insect diet, resistant PBW were detected in low frequencies at 10 out of 17 Arizona locations sampled in 2001 and ranged from 0.0 to 4.0%. Though significantly more abundant than in the previous three seasons, resistant PBW were statistically less abundant in 2001 than they were in 1997. One collection from Paloma, AZ, had 4.0% survivors (uncorrected, actual survival) in bioassays of 10 μg/ml and samples from Coolidge, Maricopa, and Parker Arizona yielded • 1.0% survivors of this concentration. Susceptibility of a limited numbers of 2001 collections of PBW from California, New Mexico and Texas is also reported. Bioassays of 2002 collections are underway at the time of this writing. In a parallel effort, field efficacy of Bt cotton against PBW was documented at five to 39 Arizona locations per year since 1995 by collecting cotton bolls at seasons’ end and counting PBW and exit holes. In 39 pairs of adjacent Bt and non-Bt fields evaluated in 2001 by the Arizona Cotton Research and Protection Council, mean end-of-season pink bollworm infestation levels were > 15% for non-Bt fields and were < 0.15% in adjacent Bt fields. Thus, field observations indicated that performance of Bt cotton continued to be excellent throughout Arizona in the 2002 season.
    • Reduced Tillage Effects on Irrigation Management in Cotton

      Martin, E. C.; Adu-Tutu, K. O.; McCloskey, W. B.; Husman, S. H.; Clay, P.; Ottman, M.; University of Arizona, Tucson, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Conservation or reduced tillage practices in cotton-based crop rotation systems were studied in field experiments initiated at Marana, Coolidge and Goodyear in 2001. Following barley cover and grain crops, soil and water management assessments were made during the 2002 cotton season at the three sites. Cover and grain crop residues and a lack of tillage prior to planting cotton or during the cotton season increased the infiltration of irrigation water into coarsetextured soils, slowed irrigation advance times, and increased the amount of irrigation water used at two of the three sites compared to conventional tillage treatments.
    • Short Staple Variety Trial in Cochise County, 2002

      Clark, L. J.; Norton, E. R. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Twelve varieties were tested including two New Mexico Acalas, two California Acalas from CPCSD, the new Arizona Cotton Grower’s variety and seven other upland varieties. Among the twelve varieties, eight contained the roundup resistant gene, which is very important for the high elevation trials. Four of these roundup resistant varieties were stacked gene varieties also containing the Bollgard trait. The highest yielding variety in the trial was 1517-99, with a yield approaching 800 pounds of lint per acre. This yield was lower than seen in 2001. In addition to the plant mapping data and HVI data which are provided, estimates of the crop values are also included in this report.
    • Late Season Crop Management Effects on Fiber Micronaire

      Silvertooth, J. C.; Galadima, A. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      A field experiment was conducted during the 2002 growing season to evaluate a central Arizona grower’s method of addressing cotton fiber micronaire based on the management and timing of his agronomic inputs. The success of his inseason management, irrigation termination decision combined with his method of defoliation has led to a consistent production of premium fiber micronaire in recent years. Steps to accomplish crop defoliation and the subsequent mixing of seed cotton from the top (younger) and lower (older) bolls achieved at harvest are intended to keep the micronaire at premium levels and further prevent discounts on the crop. A companion study was conducted at the University of Arizona Maricopa Agricultural Center (MAC-1,175 ft. elevation) in an effort to duplicate the grower’s late season crop management operations. This study consisted of two treatments, a control (conventional) which received an application of 10 oz. Ginstar combined with ½ pt. surfactant in 20 gal./acre carrier and a treatment which received the conventional treatment in addition to a pre-defoliation Accelerate and a post-defoliation Gramoxone applications consistent with the grower’s methods. Plant growth and development measurements taken inseason revealed that height to node ratio (HNR) and fruit retention (FR) levels estimates were similar for both sites (grower fields and MAC study). Lint yield estimates indicated no difference between the conventional defoliation and the treatment receiving additional compounds at MAC. Results of the analyses performed on final micronaire data also indicated no significant difference in micronaire values between the two methods of defoliation and late season management at MAC. Fiber micronaire values exceeded the premium level (>5.0) for both treatments at MAC. However, results obtained from the cooperator-grower gin records revealed that average fiber micronaire for all of the fields monitored in this project were at premium level (<5.0).
    • 2002 Low Desert Upland Cotton Advanced Strains Testing Program

      Husman, S.; White, K.; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Upland cotton advanced strains, commercial check comparison varieties, and national standard comparison varieties were evaluated in replicated field studies at three locations in 2002. The test sites include Safford, AZ, Maricopa, AZ., and Yuma, AZ. Six seed companies submitted a maximum of five advanced strains entries per location. Three commercial check varieties were used at each site for comparison purposes and included SG747, DP33B, and ST474. Four National Standard varieties were used at the Safford and Maricopa sites for comparison purposes and included Acala 1517-99, Atlas, DP458BR, and ST4892BR.
    • Evaluation of Irrigation Termination Effects on Fiber Micronaire and Yield of Upland Cotton, 2000-2002

      Silvertooth, J. C.; Galadima, A. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Arizona has experienced a trend of increasing fiber micronaire values in recent years resulting in substantial discounts on fiber value. There is some evidence to suggest that irrigation termination (IT) management can influence fiber micronaire. Field studies were conducted in 2000, 2001, and 2002 at the University of Arizona Maricopa Agricultural Center (1,175ft. elevation) and in 2001 and 2002 at the Yuma Valley Agricultural Center (YVAC; 150 ft. elevation) to evaluate the effects of three dates of irrigation termination on the yield and fiber micronaire of several Upland cotton varieties. Three dates of irrigation termination (IT1, IT2, and IT3) were imposed based upon crop development into cutout. The earliest irrigation termination date, IT1 was made slightly ahead of an optimum date to provide sufficient soil-water such that bolls set at the end of the first fruiting cycle would not be water stressed and could be fully matured. Thus, the IT1 date was imposed to try to reduce overall micronaire. The second termination (IT2) date received one additional irrigation over an optimal point for the completion of the first cycle fruit set and two irrigations beyond IT1. The final (IT3) date (late September) was imposed so that soil moisture would be sufficient for the development of bolls set up through the last week of September, thus providing full top-crop potential. In general, lint yield and micronaire results revealed significant differences among the IT treatments. Micronaire and lint yield values consistently increased with later IT dates.
    • 2002 Upland Cotton Variety Evaluation in Graham County

      Norton, E. R.; Clark, L. J. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      A field trial was established during the 2002 growing season as part of the statewide Upland Cotton Variety Testing Program. This trial was located in Thatcher with Dennis Layton Farms as the cooperator. The location was one of eleven around the state. Nine varieties from 5 different participating seed companies were evaluated in this study. Several varieties performed well including Deltapine DP555BR, a new variety from Deltapine, DP655BR, Fiber Max 989BR and 991R. Results indicate that DP655BR, which has traditionally been grown in this valley, continues to be an excellent choice. However, there are several other varieties that have recently come onto the market that provide very strong alternatives for cotton production in the Upper Gila Valley.
    • Residual Soil Nitrogen Evaluations in Irrigated Desert Soils, 2002

      Silvertooth, J. C.; Galadima, A.; Norton, E. R. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Field experiments investigating N fertilizer management in irrigated cotton production have been conducted for the past 15 seasons at three Arizona locations on University of Arizona Agricultural Centers (Maricopa, MAC; Marana, MAR; and Safford, SAC). In 2002, residual N studies were conducted at two of these locations (MAC and MAR). The MAC and SAC experiments have been conducted each season since 1989 and the Marana site was initiated in 1994. The original purposes of the experiments were to test nitrogen (N) fertilization strategies and to validate and refine N fertilization recommendations for Upland (Gossypium hirsutum L.) and American Pima (G. barbadense L.) cotton. The experiments have each utilized N management tools such as pre-season soil tests for NO₃⁻-N, in-season plant tissue testing (petioles) for N fertility status, and crop monitoring to ascertain crop fruiting patterns and crop N needs. At each location, treatments varied from a conservative to a more aggressive approach of N management. Results at each location revealed a strong relationship between the crop fruit retention levels and N needs for the crop. This pattern was further reflected in final yield analysis as a response to the N fertilization regimes used. The higher, more aggressive N application regimes did not consistently benefit yields at any location. Generally, the more conservative, feedback approach to N management provided optimum yields at all locations. In 2001, a transition project evaluating the residual N effects associated with each treatment regime was initiated and no fertilizer N was applied. Therefore, all N taken-up by the crop was derived from residual soil N. In 2001, there were no significant differences among the original fertilizer N regimes in terms of residual soil NO₃⁻-N concentrations, crop growth, development, lint yield, or fiber properties. The lint yields were very uniform at each location and averaged 1500, 1100, and 850 lbs. lint/acre for MAC, MAR, and SAC, respectively. In 2002, results were very similar at the MAC and MAR locations. Trends associated with residual fertilizer N effects are not evident at either location just two seasons following N fertilizer applications.
    • Pima Cotton Regional Variety Trial, Safford Agricultural Center, 2002

      Clark, L. J.; Carpenger, E. W.; Norton, E. R. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Twenty long staple varieties were tested in a replicated small plot trial on the Safford Agricultural Center in Graham County at an elevation of 2950 feet. The highest yielding variety in this study was HA 195 with a yield of 1419 pounds of lint per acre. This interspecific hybrid was the highest yielding variety in the 2001 study also (1). DP 340, one of Olvey’s varieties, was the highest yielding non-hybrid variety in the study; it yielded over 1200 pounds of lint per acre. Yield and other agronomic data as well as fiber quality data are contained in this paper along with estimated values of the lint.
    • Short Staple Variety Trial in Virden, NM, 2002

      Clark, L. J.; Norton, E. R. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Twelve varieties were tested including two new herbicide resistant entries from California, Riata and Nova, two New Mexico Acalas, seven roundup resistant entries from Delta and Pine Land Co., Stoneville, SureGrow and FiberMax, and the new variety developed for the Arizona Cotton Grower’s Association, AG 3601. The highest yielding variety in the trial was FM 989 with a yield of 1045 pounds of lint per acre. It was also the highest yielding variety at this location last year. The Acala 1517-99 placed second in yield at 1039 pounds of lint per acre. HVI data are also included in this report.
    • 2002 Evaluation of a Twin-Line Cotton Production System in Graham County

      Norton, E. R.; Clark, L. J.; HUsman, S. H. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      A series of studies were conducted around the southeastern region of the state during the 2002 cotton growing season to evaluate the effects of a twin-line (TL) planting configuration on fiber quality and lint yield. Two of the three studies were conducted on grower cooperator fields with large block comparisons or demonstrations of TL versus single-line (SL) configurations. Fiber quality was essentially the same for both demonstration locations. Yield differences were observed in both locations with the Graham County location experiencing a 130 lb lint yield decrease in the TL plots. The Cochise County location experienced a 328 lb lint yield increase in the TL plots. The third study was a split plot within a randomized complete block design with planting configuration (TL or SL) as the main effect and variety as the sub-unit effect. . No significant differences were detected in the main effect, sub effect or the interaction with respect to yield. Trends were observed however, indicating less difference between the TL and SL with respect to yield for varieties with a more columnar growth pattern. Fiber quality results indicated no significant differences among any of the treatments
    • Phosphorus Fertility Evaluation in Graham County

      Norton, E. R.; Clark, L. J. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      A field study was implemented in 2002 in the Upper Gila River Valley of Safford to investigate the effects of varying phosphorus (P) fertilization rates on yield and quality of Upland cotton. This study is a continuation of work performed in this valley that began in 1998. This study was organized in a randomized complete block design with four treatments including four rates of 10-34-0 fertilizer, 0, 15, 30, and 45 gallons per acre (gpa) replicated 4 times. Lint yield results indicate a positive response to the application of 10-34-0 fertilizer with yield increasing linearly up to 30 gpa. The 45 gpa treatment resulted in a slightly lower yield than the 30 gpa treatment. This was likely due to the high level of nitrogen (N) fertilizer and excessive vegetative growth at the expense of reproductive growth (yield) that occurred in treatment 4.
    • Evaluation of Crop Management Effects on Fiber Micronaire, 2000-2002

      Silvertooth, J. C.; Galadima, A.; Tronstad, R. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Arizona has experienced a trend toward increasing fiber micronaire values in recent years resulting in substantial discounts on fiber value. There is some evidence to suggest management can influence fiber micronaire. Approximately 560 cases were identified in cotton production areas in Arizona ranging from the lower Colorado River Valley to near 2,000 ft. elevation with grower cooperators in the 2000-2002 seasons. Field records were developed for each field by use of the University of Arizona Cotton Monitoring System (UA-CMS) for information such as variety, planting date, fertility management, irrigation schedules, irrigation termination, defoliation, etc. Routine plant measurements were conducted to monitor crop growth and development and to identify fruiting patterns and retention through the season. As the crop approached cutout and the lower bolls began to open, open boll samples were then collected from the lowest four, first position bolls (theoretically the bolls with the highest micronaire potential on the plant) from 10 plants, ginned, and the fiber was then analyzed for micronaire (low 4). From that point forward, total boll counts per unit area and percent open boll measurements were made on 14-day intervals until the crop was defoliated. Following defoliation, final plant maps were performed. Relationships among low 4 sample micronaire, irrigation termination (IT), defoliation, and final crop micronaire were analyzed. Results indicate strong relationships with final fiber micronaire for factors such as total heat units (HU) accumulated by the crop from planting to IT, variety, region of production (environment), and green boll load at cutout. Results showed that as total HU accumulated from planting to IT exceeded 2945 that micronaire levels increase significantly, especially for some districts (Paloma and Maricopa) and producers.
    • Effects of Foliar Fertilizers Containing Calcium on Early June Planted Cotton in the Palo Verde Valley, 2000

      Rethwisch, M. D.; Duran, E.; Seiler, J.; Nelson, J.; Hayden, P. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Three foliar fertilizers containing calcium were applied at first bloom to evaluate effects on late planted (June 1) cotton in the Palo Verde Valley. Application of Calcium Metalosate resulted in increased retention percentages when compared with other foliar fertilizers at 21 days post treatment as well as more nodes/plant and calculated fruiting structures/plant. Yields did not reflect these differences however, as highest overall yields were from the untreated check, which yielded about 100 lbs. of lint/acre more than foliar fertilizer treatments. Foliar treatments did result in numerically lower micronaire and longer fibers from first pick cotton. Cotton from the first pick Calcium Metalosate treatment was strongest, but similar to other treatments. Foliar treatments did result in increased cotton value/acre by $65-95/acre, but differences noted were not consistent across field. Increased value noted for fertilizers was associated with areas of field with lowest retention rates in the untreated check at three weeks post application, and further reduction in lint quality value of untreated cotton, due perhaps to crop stresses.
    • Cry1Ac Toxic Protein in Overwintered Volunteer and Annual Seeded NUCOTN 33B7 (Bt) and Deltapine (DPL) 5415 Cottons: Efffects on Pink Bollworm (PBW) and Tobacco Budworm (TBW) Larval Mortalities

      Henneberry, T. J.; Forlow Jech, L.; de la Torre, T.; Maurer, J.; USDA-ARS, PWA, Western Cotton Research Laboratory, Phoenix, AZ 85040-8803 (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Season-long protection from pink bollworm (PBW), Pectinophora gossypiella (Saunders), damage has been outstanding each year, since 1996, in NuCOTN 33B7 (Bt) commercial cotton plantings in Arizona. Cotton is a perennial plant and whether or not the insect toxic protein was expressed in overwintered Bt cotton was unknown. This could be a consideration in Arizona Bt resistance monitoring in the field since occasional overwintered volunteer cotton plants may occur. In 2002 we studied Cry1Ac levels in overwintered volunteer Bt cotton plants and determined their effects on PBW and tobacco budworm (TBW), Heliothis virescens F., larval mortalities. No TBW larvae survived three-day feeding periods on Bt leaves compared with < 3% TBW larval mortality feeding on DPL 5415 leaves. PBW larval mortality after three-day feeding on flower buds or seven-day feeding on Bt cotton bolls exceeded 98% compared with 40 to 41 % mortality feeding in DPL 5415 fruiting forms. Cry1Ac toxic protein in leaves, flower buds or cotton bolls of overwintered Bt cotton was not significantly different compared with 2002 seeded cotton.
    • Cabbage Looper, Tobacco Budworm, and Beet Armyworm Larval Mortalities, Development and Foliage Consumption on Bt and Non-Bt Cottons

      Henneberry, T. J.; Forlow Jech, L.; de la Torre, T.; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Tobacco budworm (TBW), Heliothis virescens (F.), larvae were highly susceptible to feeding on Bt cotton leaves or flower buds with 100% and 96% mortality occurring within 4 days, respectively, compared to an average mortality of 95% for cabbage looper (CL), Trichoplusia ni (Hübner), and 57% for beet armyworm (BAW), Spodoptera exigua (Hübner), after 14 days feeding on Bt leaves. Larval weights, of CL and BAW after 7, 10, or 14 days of feeding on Bt leaves were lower compared with those feeding on non-Bt cotton leaves. BAW, CL, and TBW larvae consumed significantly less Bt leaf area per feeding day compared with DPL 5415.
    • 2002 Planting Date by Variety Evaluation in Graham County

      Norton, E. R.; Clark, L. J.; Carpenter, E. W. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      A single field study was established during the 2002 growing season to evaluate the effects of planting date (PD) on the yield and fiber quality characteristics of several cotton varieties commonly grown in the Upper Gila River Valley of Safford. Seven varieties were chosen for evaluation in 2002 ranging from early to medium-full varieties. These seven varieties were planted on three separate planting dates (2 April, 15 April, and 3 May) in a split-plot within a randomized complete block design with four replications. Overall analysis of variance revealed significant differences due to PD (OSL=0.0291) but no significant differences among varieties (OSL=0.5164) or in the interaction between PD and variety (OSL=0.4052). Four of the varieties evaluated produced the highest yield with the later PD (3 May). The remaining three varieties performed best with the 2nd PD (15 April).
    • Plant Population Effect on Yield and Fiber Quality of Three Upland Cotton Varieties at Maricopa Agricultural Center, 2002

      Galadima, A.; Husman, S. H.; Silvertooth, J. C. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      A field experiment was conducted at the University of Arizona Maricopa Agricultural Center (MAC – 1100 ft. elevation) in 2002 to evaluate plant population relationships with conventional row spacing under a range of high population conditions with new Upland cotton (Gossypium hirsutum L.) varieties. The varieties, which included AG3601, DP458BR, and STV4892BR, were each planted to six densities of 15,000, 30,000, 45,000, 60,000, 75,000, and 90,000. Inseason plant measurement data revealed crop vigor and fruit retention levels were well within the optimum threshold for all varieties and populations. There was no interaction between variety and population in terms of lint yield and fiber quality parameters. However, results show significant differences in lint yield and fiber strength among varieties but not the fiber micronaire. In addition, higher population had no significant effect on lint yield or fiber quality. Higher populations had no effect in lowering fiber micronaire to premium levels as well.
    • Making Late Season Decisions to Terminate Insecticide Use Against Lygus

      Ellsworth, Peter C.; Barkley, Virginia; Department of Entomology & Maricopa Agricultural Center (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      The focus of our 2002 field study was to answer a fundamental question in insect control. Once spraying has begun for a particular pest, when should it stop? In this case, we are faced with the question of when to discontinue sprays for Lygus hesperus in cotton. Cotton is susceptible to Lygus any time there are productive squares on the plant. This study developed a series of worst-case scenarios in which to provide information on timing of the latest possible sprays of economic benefit. By late planting (30 May) varieties from three different maturity groups, we were able to examine Lygus control dynamics just prior to, at, and after cutout — initiation of cut-out was defined as NAWF = 5. We found large differences in yield among the four Lygus chemical termination (LT) treatments. The earliest termination (LT1, 2 weeks prior to cut-out) suffered the largest losses to Lygus, ca. 20–50% of the maximum yield. Conversely, extending Lygus chemical control 1–3 weeks after cut-out (LT3 & LT4) provided no yield benefit whatsoever, regardless of the variety examined. Maximum yields and maximum profits were gained in the LT2, where Lygus controls were continued up to 1 week prior to cutout. Given that there was only 1 week separating the LT1 and LT2 timings, it is clear that timing is absolutely critical. The timing used in this study corresponds with previously established threshold guidelines; treat when there are at least 15 total Lygus with at least 4 nymphs per 100 sweeps. Levels far exceeded this threshold late in the season, yet additional chemical controls after cut-out provided no additional yield or control benefits. Further, we have confirmed that nymphs are the life stage of major concern with, by far, the most capacity to reduce yields. Nymphal reductions were well-correlated with yield enhancement. The best timing (LT2) achieved ca. 93% reduction in nymphal densities during the critical 3- week period around cut-out. In contrast, adult numbers were reduced by only 16% during the same period. These results establish an upper bound for treatment of Lygus, no later than 1 week prior to cut-out; however, more work is necessary to identify if earlier cessation is possible under more normal planting conditions.
    • Arizona Upland Cotton Variety Testing Program, 2002

      Husman, S.; Norton, R.; Norton, E.; Clay, P.; Clark, L.; Zerkoune, M.; White, K.; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Each year the University of Arizona conducts variety trials across the state to evaluate the performance of upland cotton varieties. These tests provide unbiased data on the performance of varieties when tested side-by-side under typical production practices. In 2002, we planted a total of 9 trials, two in the Yuma region (Yuma County), four in the central region (Maricopa and Pinal counties), one in the southern region (Pima county), and two in the eastern region (Graham, Greenlee, and Cochise counties). We tested nine to twelve commercially available varieties at each test site. The purpose of this report is to present the results of the 2002 tests conducted in the Yuma, western, central, southern, and eastern regions of Arizona.