• Residual Soil Nitrogen Evaluations In Irrigated Desert Soils, 2005

      Silvertooth, J. C.; Galadima, A.; Norton, E. R.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      Field experiments aimed at investigating N fertilizer management in irrigated cotton production have been conducted for the past 16 seasons at three Arizona locations on University of Arizona Agricultural Centers (Maricopa, MAC; Marana, MAR; and Safford, SAC). In 2001-2005, 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 (G. 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 N fertilizer was applied. Therefore, all N taken-up by the crop was assumed to be derived from residual soil N. However irrigation water analysis showed that NO₃⁻-N concentration levels added to the crop ranged from about 5-9 ppm. In 2001-2005 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 season. Trends associated with residual fertilizer N effects are not evident at either location for five seasons following N fertilizer applications.
    • A Review of 10 Years of Phosphorus Fertility Research in Arizona

      Norton, E. R.; Silvertooth, J. C.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      Management of phosphorus (P) fertilizer in Arizona cotton production systems has been studied for many years. A series of field experiments have been conducted across Arizona since 1989 with the most recent trial conducted in 2004. These trials represent over 15 site-years of research investigating the response of upland cotton (Gossypium hirsutum L.) to the application of P fertilizers and have been conducted over a wide range of environmental conditions. A summary of these field trials is presented in this paper. All trials were structured in a similar fashion with a control being compared to various rates of applied P fertilizer ranging from 0 to over 120 lbs P₂O₅ per acre. All trials had a similar experimental design with large plots (minimum of 0.16 acres) and treatments arranged in a randomized complete block design with a minimum of three replications in all cases. All applications were made either pre-plant or shortly after stand establishment. A wide range of soil test P levels were evaluated at many locations across the State. Results indicate that the critical level for sodium bicarbonate extractable P is 5 parts per million (ppm) with a 90% probability of a positive lint yield response when soil test levels fall below the critical level. Effective (positive crop response) fertilization rates range from 60-90 lbs of P₂O₅ per acre.
    • Pistil and Style Elongations Beyond the Anthers: Results From 2005 Field Experimentation

      Rethwisch, Michael D.; Luna, Manuel M.; Ramos, D. Michael; Wellman, Jessica J.; Williams, Michael T.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      A rapid heat increase from the high 80s-low 90s to high temperatures of 110o F on May 21 and 22, 2005, was recorded in the Blythe, CA, area, resulting in abnormal cotton flowers in mid-June, being especially characterized by elongated styles and stigmas being beyond the anthers. Two different cotton variety trials conducted in the Palo Verde Valley allowed data to be collected semi-weekly beginning June 17-20, with 100+ flowers per plot examined in each plot (four replications) of each of the 14 cotton variety entries. Every cotton variety had an average of 90+% of flowers expressing heat stress abnormalities (elongated styles) at the beginning of data collection even though the trials varied by planting date and location. Abnormal flowers were noted for several weeks, with some stigmas 21 mm beyond the anthers. Varieties differed in their responses to heat stress as measured by elongation later in the summer. Limited data were also collected for fruit retention and correlated with length of stigma extension beyond anthers. Retention percentages decreased as distance between anthers/stigmas increased, however boll size increased with less retention, possibly through nutrient partitioning. Various foliar fertilizers containing calcium were also evaluated for their effect on stigma elongations of DPL 449BR cotton. Significant differences existed for stigma elongations, with 2.5 qts./acre of CalMax resulting in statistical reduction of elongation when compared with the untreated check at 3 weeks after application. Statistical differences did not exist at four weeks although statistical differences did exist at this date for the percentage of flowers affected, with the highest percentage (81.7%) noted in untreated cotton.
    • Irrigation Termination Effects on Cotton Yield and Fiber Quality

      Silvertooth, J. C.; Galadima, A.; Tronstad, R.; Tronstad, Russell; Norton, E. Randy; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      Field experiments were conducted in 2004 and 2005 at the University of Arizona Maricopa Agricultural Center (1,175ft. elevation) to evaluate the effects of five irrigation termination (IT1, IT2, IT3, IT4, and IT5) dates on yield and fiber micronaire of eleven Upland cotton varieties and one Pima variety. In addition, the economic relationships of IT treatments were also evaluated. The experimental design was a split plot in a randomized complete block design with three replications. The main treatments included the five IT dates and the subunits consisted of 11 Upland varieties and a Pima variety. The first two IT treatments (IT1 and IT2) were imposed with the intention of terminating irrigations very early and pre-maturely at peak bloom. Based upon current UA recommendations for IT to complete a single cycle fruit set, the more optimal date of IT would have included one or two additional irrigations (beyond IT1 and IT2). In this experiment, IT2 was structured to provide an additional (one) irrigation just past peak bloom. For the IT3 plots, the intention was to attempt to time termination in advance of cutout. The 2004 and 2005 IT4 and IT5 were imposed to attempt to complete the primary fruiting cycle development and produce a second cycle fruit set that require irrigations until late August and late September, respectively. In general, lint yield and micronaire results revealed significant differences among the IT treatments and varieties. In a similar fashion to a previous set of IT experiments (2000-2002), lint yield and micronaire values consistently increased with later IT dates. The best combined lint yield and micronaire results were achieved with IT4 date, which received 12 and 18 in. less irrigation water than IT5 in 2004 and 2005, respectively. In 2004 and 2005, the 12 and 18 in. water saved equate to approximately 20% and 30% less water used under the conventional practice, respectively. The average marginal value of water for all eleven Upland varieties in going from IT1 to IT2, IT2 to IT3, IT3 to IT4, and IT4 to IT5 for November 2004 prices and low carrying costs is calculated at $320.07, $150.15, $100.54, and -$28.16 per acre-foot of water. If steeper mike discounts (November 1999), a lower base lint price (45¢/lb.), and higher costs (i.e., more costly insecticide and chemical costs) are imputed to extend the crop, the marginal value of an acre-foot of water for all Upland varieties and replications in going from IT1 to IT2, IT2 to IT3, IT3 to IT4, and IT4 to IT5 is estimated at $164.04, $48.15, $12.97, and -$94.79. Profitability and the value of water for extending the season varies quite markedly between different varieties and termination dates.
    • Effect of Heat Unit Accumulation on Cotton Defoliation, Lint Yield and Fiber Quality

      Clay, P. A.; Young, K. M.; Taylor, E. R.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      This study evaluated the effectiveness of defoliating at various heat unit accumulations: 630HU, 730 HU, 830 HU, 930 HU, 1030 HU, 1130 HU and 1330 HU and impact on lint yield and fiber quality. American Upland cotton variety DP 449 BR was planted on 12 April 2005 at the University of Arizona Maricopa Agriculture Center in Maricopa, Arizona. The experimental design was a split plot with four replications of each of seven defoliation timings. Final irrigation occurred on 05 August 2005. When heat unit accumulation reached 630 HU (on 20 August 2005), 730 HU (on 01 September 2005), 830 HU (on 04 September 2005), 930 HU (on 08 September 2005), 1030 HU (on 12 September 2005), 1130 HU (on 19 September 2005) and 1330 HU (on 27 September 2005) using the 86/55 F model chemical defoliants were applied. A mixture of Def (tribufos) at 24 oz/A, Dropp (thidiazuron) at 0.2 lb/A and Prep (ethephon) at 24 oz/A was applied using a high clearance research sprayer. The earliest treatments (630 and 730 HU accumulated) had significantly fewer open bolls at defoliation than those that received later treatments. At harvest, this trend disappears: the latest application (at 1330 HU) had significantly fewer open bolls than any other timing. Seven days after defoliant application (7 DAT), highest levels of defoliation were observed in the following treatments in descending order: 830 HU, 630 HU, 1130 HU, 930 HU and 730 HU followed by 1030 HU and 1330 HU. At harvest, there were no significant differences among mean defoliation percentages with the exception of the 1330 HU timing, which was significantly less defoliated than any of the other timings. Highest lint yield and gin turnout were observed in the earliest defoliation timings, lowest in the later timings. No significant differences in micronaire, length or uniformity were observed between defoliation timings. Differences did occur in fiber strength which was highest in earlier timings and lowest in the last timing, but all were above the discount level.
    • Evaluation of Various PPO Inhibitors as Defoliants for Upland Cotton

      Clay, P. A.; Young, K. M.; Taylor, E. L.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      This study was conducted in 2005 at the University of Arizona Maricopa Agricultural Center. The objective was to compare the performance of various PPO inhibitors [Aim (carfentrazone-ethyl), ET (pyraflufen-ethyl), Blizzard (fluthiacet-methyl) and Resource(flumiclorac)] as stand-alone defoliation treatments either as a single or sequential application, or tank mixed with Ginstar or CottonQuik. Plots were arranged in a randomized, complete block design with four replicates. Each plot was composed of four, 40 inch rows that measured 25 feet long. Delta and Pine variety DP 449BR was planted on 12 April 2005. Treatments included: Ginstar @ 6 oz/A, Ginstar @ 8 oz/A, Aim @ 1 oz/A, ET @ 1.5 oz/A, Resource @ 8 oz/A and Blizzard @ 0.5 oz/A, Aim followed by Aim, ET followed by ET, Blizzard followed by Blizzard, Resource followed by Resource, Ginstar @ 6 oz/A plus Aim, Ginstar plus ET, Ginstar plus Resource, Ginstar plus Blizzard, CottonQuik at 32 oz/A plus Aim, CottonQuik plus ET, CottonQuik plus Resource, and CottonQuik plus Blizzard. All treatments receiving a PPO inhibitor also contained a Crop Oil Concentrate at 1% v/v. None of the PPO inhibitors applied as a single application performed as well as Ginstar at either the 6 oz/A or 8 oz/A rates. At 14 days after treatment (DAT), both Aim and Blizzard achieved 74% defoliation, Resource 69% and ET 60%. For sequential applications at 14 DAT, Aim at 1.5 oz/A followed eight days later by a second application of Aim performed as well as the standalone applications of Ginstar at 6 oz/A and 8 oz/A. Two applications of Blizzard at 0.5 oz/A eight days apart defoliated as well as Ginstar at 6 oz/A. Tank mixing any of the four PPO inhibitors with Ginstar did not improve defoliation over Ginstar alone, at either rate nor did defoliation rates decrease as a result of the mixes. A mixture of Aim + CottonQuik (75%) defoliated as well as a standalone treatment of Ginstar (82%).
    • Evaluation of Contact Herbicides as a Follow-up Defoliation Treatment in Upland Cotton

      Young, K. M.; Clay, P. A.; Taylor, E. L.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      Studies were conducted in 2002, 2004, and 2005 at the University of Arizona Maricopa Agricultural Center located near Maricopa, Arizona. Objectives of the study were to evaluate the efficacy of contact herbicides for defoliation as a second application and evaluate any potential improvement in lint return (gin turnout), fiber quality and overall lint value. In 2002, Delta and Pine cultivar 458 BR was planted on 17 April. In 2004 and 2005 Delta and Pine cultivar 449 BR was planted on 13 May and 12 April respectively. In all years, plots were 13.33 ft wide and 25 ft long and treatments were arranged in a randomized complete block with four replications. Irrigation was terminated at cutout (NAWF=5) and defoliation treatments were initiated 22 days later. All plots received an initial defoliation treatment of thidiazuron plus diuron (Ginstar) at 8 oz/A. In 2002 and 2004, follow-up applications occurred seven days after initial defoliation, and included the following treatments: paraquat (Gramoxone Max) at 10.7 oz/A plus nonionic surfactant at 0.25%v/v, flumiclorac (Resource) at 8 oz/A plus crop oil concentrate (COC) at 1% v/v, pyraflufen (ET) at 1.5 oz/A plus COC at 1% v/v or carfentrazone (Aim) at 1.0 oz/A plus COC at 1% v/v. In 2005, follow-up application occurred eight days after initial defoliation and included the same treatments as 2002 and 2004 with the addition of fluthiacetmethyl (Blizzard) at 0.5 oz/A plus COC at 1% v/v and an adjustment of the Gramoxone Max rate to 20 oz/A. For comparison purposes, in all years, one treatment did not receive a follow-up application. In 2002 and 2004, percent defoliation was significantly higher in treatments that received an application of Ginstar followed by Aim, Resource, ET or Gramoxone Max compared with a single application of Ginstar. However, follow-up treatment with Gramoxone Max at 10.7 oz/A provided significantly less defoliation than Aim or ET treatments. In 2005, defoliation was significantly increased by follow-up application with all of the contact herbicides evaluated, No significant differences were observed in gin turnout, lint yield or loan value in the years these variables were evaluated.
    • Comparative Responses of Three Cotton Varieties to Mid-July 2005 Application of Chaperone™ in the Palo Verde Valley

      Rethwisch, Michael D.; Milke, Jose; Wellman, Jessica J.; Luna, Manuel; Ramos, D. Michael; Van Dyke, Joe; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      Chaperone™ was applied in mid-July to three different cotton varieties (DPL 449BR, DPL 555BR, STV 5599BR) being grown in the same field. Varieties differed in their responses, with application of Chaperone™ resulting in fewer fruiting structures per plant than untreated DPL 449BR or STV 5599BR, but more such structures in DPL 555BR. Seed cotton yields were increased in DPL 555BR by almost 300 lbs./acre by application of Chaperone™, but were only about 20 lbs./acre greater in the other two varieties. A higher percentage of lint in seed cotton was associated with Chaperone™ application in both DPL 449BR and STV 5599BR, but a lower percentage in DPL 555BR. Calculated lint yields increased in both DPL 449BR and STV 5599BR, but yields were almost identical for treated/untreated DPL 555BR in this experiment. Application of Chaperone™ resulted in a slight increase in fiber uniformity in all three varieties.
    • Comparison of Three Plant Growth Regulator Products on April Planted DPL 555BR Cotton, 2005

      Rethwisch, Michael D.; Swan, Ron; Luna, Manuel; Ramos, D. Michael; Wellman, Jessica; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      Three plant growth enhancement treatments were applied to April-planted DPL 555BR cotton on the morning of July 2, 2005. Plant parameter data were obtained during July, and yield and quality data were obtained at harvest in December. Usage of ChaperoneTM resulted in decreased potassium and phosphorus levels in petioles, as well as increased amounts of leaf chlorophyll. Treatments initially resulted in less fruiting structure/plant but had more than the untreated cotton at 26 days post treatment, with highest numbers per plant noted from the HappyGroTM + PhotoGro treatment. Each treatment resulted in less seed cotton and lint per acre than the untreated cotton. Less spotting associated with treated cotton increased the lint strength and increased trash levels. The AuxiGro® WP + CalMax® + Foliar Pride treatment resulted in the highest fiber strength per pound and lint value.
    • Field Comparison of Various Plant Growth Enhancement Products on DPL 449BR Cotton, 2005

      Rethwisch, Michael D.; Luna, Manuel M.; Ramos, D. Michael; Wellman, Jessica J.; Reay, Mark; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      Three plant growth enhancement chemistries (AuxiGro®, ChaperoneTM, HappyGroTM) were evaluated on DPL 449BR cotton during the summer of 2005, Application were made during mid-July to late planted cotton to evaluate and compare effects of these products on cotton growing under severe heat and growth stress to determine if such chemistries could overcome this stress. Two foliar fertilizers were included with two formulations of AuxiGro® to determine if differences associated with these treatments existed. Usage of HappyGroTM = PhotoGroTM resulted in the most fruiting structures/plant while treatments that included ChaperoneTM resulted in reduced numbers of structures when compared with the untreated check on August 24. Highest yields among products tested were noted for the formulations of AuxiGro® 518 which were slightly higher than the untreated check. Quality was improved in comparative formulations of AuxiGro® by inclusion of CalMax® + First Choice® Foliar Pride when compared with First Choice® Bollster.
    • Effects of Goëmar® BM86 and Mepiquat Chloride on DPL 449BR/DPL 494R Cotton

      Rethwisch, Michael D.; Cox, Tim; Ramos, D. Michael; Luna, Manuel; Wellman, Jessica; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      A field experiment compared several rates of mepiquat chloride and Goëmar® BM86 on Upland cotton in the Palo Verde Valley during 2005 for their effects on cotton growth and yields. Leaf chlorophyll levels were significantly increased in DPL 449BR by usage of mepiquat chloride on initial samples dates after applications, and these treatments also effected cotton heights. Retention percentages and numbers of fruiting structures per plant were initially increased by treatments which contained Goëmar® BM86, although late in the season significant differences existed between Goëmar® BM86 treatments as a result of interaction with mepiquat chloride. All treatments resulted in a slight (0.01 inch) increase in fiber length as well as staple, resulting in increased lint value. The combination treatment of Goëmar® BM86 plus 12 oz./acre of mepiquat chloride had highest cotton value ($1,035/ acre), and was worth $178/acre more than the untreated check.
    • Interaction of Cotton Varieties and Rhizoctonia solani: Effects on Resultant Plant Populations, 2005

      Rethwisch, Michael D.; Reay, Mark; Turini, Thomas A.; Swan, Ron; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      Eight varieties were evaluated under field conditions for resultant plant populations after field infection with Rhizoctonia solani. Highest plant populations were noted in Delta and PineLand 454BR, followed by three other Delta and PineLand (DPL) varieties. Stoneville and Phytogen cotton varieties had reduced plant stands compared to DPL varieties at approximately 30 days after planting. DPL 454BR, which had the highest plant population, also had earlier growth and establishment than other varieties which is thought to have helped plant survival. Although all seed was treated with multiple fungicides, seed of DPL varieties was treated with several fungicide active ingredients (thiram, tridimenol) not present on seed from other varieties. Comparative increased stand on DPL varieties may be in part due to plant genetics as well as fungicide. Stand loss was noted in all varieties however. Data indicate that in-furrow application of fungicides or applications to small cotton plants may be necessary for heavier soils under cool and moist early season growing conditions in the low desert.
    • Evaluation of ReTain® on Four Low Desert Cotton Varieties During 2005 Heat Stress Conditions

      Rethwisch, M. D.; Milke, J.; Luna, M.; Ramos, D. M.; Wellman, J.; Dulmage, A.; Williams, M.; Montañez, R.; Cardenos, J.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      Two rates of the ethylene blocker ReTain® were evaluated on four varieties of cotton in the Palo Verde Valley during the summer of 2005. Data indicated that responses to ReTain® varied greatly by variety. Application of ReTain® to DPL 555BR resulted in significant increases in numbers of fruiting structures per plant, however, these increases were not realized at harvest, as ReTain® treatments resulted in numerically reduced yields for this variety. Bolls per plant at harvest were not signficantly different for DPL 449BR, DPL 5415R or STV 5599BR. Both rates of ReTain® significantly increased uniformity of DPL 555BR cotton lint, but the lower rate of ReTain® evaluated usually resulted in slightly higher cotton lint quality for most components measured than did the higher rate. Quality and yield data were not collected for DPL 449BR, DPL 5415R or STV 5599BR.
    • Evaluation of Envoke by Pix Interaction in Arizona Cotton Production Systems

      Norton, E. R.; Borrego, H. J.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      A single trial was conducted during the 2005 cotton growing season at The University of Arizona Safford Agricultural Center to evaluate the effects of the selective herbicide Envoke in combination and alone with the plant growth regulator (Pix). Combining applications of chemical inputs in a crop production system has the potential to help reduce costs by eliminating a trip across the field with equipment. The effects of these applications on growth, development, yield, and fiber quality was investigated. The trial was arranged with seven treatments including 1) control, 2) broadcast Envoke, 3) post-direct Envoke, 4) broadcast Pix, 5) broadcast Envoke + Pix, 6) post-direct Envoke followed by broadcast Pix, and 7) broadcast Pix followed by post-direct Envoke. These treatments were imposed in both normal and high soil moisture regimes. Plots were arranged in a randomized complete block design with four replications in two separate studies (normal and high soil moisture). Plots were monitored for effects on plant growth and development throughout the season by collecting a series of plant measurements from each treatment. Effects on final lint yield and fiber quality was determined by harvesting the center two rows of each four-row plot and weighing the resultant seed cotton. A sub-sample was collected for lint turnout and fiber quality analysis. Results indicated very little differences in plant growth and development among any of the treatments in both the normal and high moisture regimes. Significant differences were observed among lint yield and fiber quality parameters. Analysis of variance indicated significant effects due to treatment in lint yield, fiber length, strength, and uniformity. Significant differences were also observed due to soil moisture with respect to micronaire and fiber strength. Significant interaction between treatment and moisture regime was observed in micronaire, fiber length, strength, and uniformity. Results indicate that even though plant growth and development did not appear to be significantly impacted by the application of Pix + Envoke, lint yield was impacted. In both the normal and high soil moisture regimes the treatment receiving the combined application of Pix and Envoke produced the lowest yield.
    • Evaluation of Plant Growth Regulator Formulations in Arizona Cotton Production Systems

      Norton, E. R.; Borrego, H. J.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      A single experiment was conducted in 2005 at the University of Arizona Safford Agricultural Center in an effort to continue to evaluate several different formulations of the plant growth regulator (PGR) mepiquat chloride. Plots were established with the cultivar Deltapine DP 655BR on 19 April 2005. Four treatments were imposed on 18 July 2005 of 16 oz./acre applications of Mepex, Pix Ultra, and Pentia, plus a control plot. Plots were four 36” rows wide and extended the length of the irrigation run of 220 feet. Plots were arranged in a randomized complete block design with four replications. Plots were monitored with respect to plant growth and development through collecting plant measurement data over the course of the season. Yield results were obtained by harvesting the center two rows of each plot and weighing the resultant seedcotton. Fiber quality was determined from a sub-sample collected from each plot at harvest. Plant growth and development trends indicated strong fruit retention levels all season with strong early season vigor. Each of the PGR applications had significant impact on plant height effectively reducing internode elongation. Lint yield results indicated increased yields for all PGR applications over the control with Pentia producing a statistically significant higher yield. Fiber quality was also impacted by PGR application. All PGR treatments had trends toward higher staple length, fiber strength, and fiber uniformity. These results are consistent with previous results indicating that PGR applications have the potential to increase yields under situations were high vigor is present.
    • Evaluation of Commercial Harvest Aid Products in Arizona Upland Cotton Production Systems

      Norton, E. R.; Borrego, H.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      A defoliation experiment was conducted during the 2005 growing season in an effort to evaluate effectiveness of the Ginstar™ defoliant alone and in combination with Cotton Quick™. This study was conducted at the University of Arizona Safford Agricultural Center on Upland (cultivar DP655BR). Plots were planted on 22 April. Treatments were arranged in a randomized complete block design with four replications and treatments that included Ginstar™ at 6 and 8 oz./acre rates and Ginstar™ at the 6 and 8 oz./acre rates in combination with various rates of Cotton Quick™ (1.5, 2, 3, and 4 pts/acre). A control, not receiving any harvest prep material was also included for a total of eleven treatments. Treatments were imposed on 3 October and evaluations were made on 14 October and 26 October. Estimations on percent leaf drop, regrowth control, and open boll were made. Lint yield was estimated by harvesting the center two rows of each plot and sub-samples were collected for fiber quality analysis. Plots were harvested on 26 October in an attempt to evaluate the boll opening effectiveness of the Cotton Quick™ material. Results indicated increased leaf drop in lower Ginstar™ rates with the addition of Cotton Quick™. Measurements of open boll percentages did not indicate any increase with the addition of Cotton Quick™ however, lint yield and fiber quality parameters would demonstrate otherwise. Lint yield slightly increased in all treatments receiving Cotton Quick™ while fiber micronaire decreased in Cotton Quick™ treatments. This would indicate a blending of less mature bolls opened with the addition of Cotton Quick™ with those already opened. Percent lint also increased in all treatments receiving Cotton Quick™.
    • Regional Extra Long Staple (ELS) Cotton Evaluation in Southeastern Arizona

      Norton, E. R.; Borrego, H. J.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      A single field trial was conducted in 2005 at the University of Arizona Safford Agricultural Center as part of the regional Extra Long Staple (ELS) cotton variety testing program. This trial was conducted to evaluate nine different ELS varieties under growing conditions of the Upper Gila River Valley. These nine varieties were planted in a randomized complete block design with four replications on 26 April 2005. All plots were managed in an optimum fashion with respect to general agronomic practices. Plot size was four rows 36” wide and 40’ in length. Lint yield was determined on 10 November by harvesting the center two rows of each plot and weighing the resultant seed cotton. Sub-samples were collected for percent lint determination and fiber quality analysis at the time of harvest. Lint yield averaged 1375 lbs/acre with a range of just over 1150 to nearly 1570 lbs lint/acre. Several experimental CPCSD varieties performed extremely well with E503 and E105 placing in the top three. The standard DP340 also placed in the top three. By comparison to the Pima S-7 variety significant advances in terms of yield are being made with the newer varieties being developed. Significant advances in fiber quality were also observed. Phytogen PHY800 performed very well with respect to fiber quality properties, particularly in comparison to the Pima S-7 standard of exceptional quality.
    • Upland Cotton Variety Evaluations in Southeastern Arizona

      Norton, E. R.; Borrego, H. J.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      Three separate Upland cotton variety evaluations were conducted in southeastern Arizona during the 2005 cotton growing season. Two locations were in Graham County, Thatcher and Ashurst, while the third location was in Cochise County in the community of Kansas Settlement. Eleven varieties were selected for both the Thatcher and Kansas Settlement locations while seven were planted at the Ashurst location. Varieties ranged in maturity from early to full at each of the three locations. All plots were arranged in a randomized complete block design with four replications. All three locations were planted on grower-cooperator fields and were managed in accordance to the individual grower styles. Plant measurements were collected over the course of the season at both the Thatcher and Ashurst locations. Lint yield was determined by harvesting the entire plot at each location and weighing the resultant seedcotton. Sub-samples were also collected at the time of harvest for percent lint estimates and fiber quality analysis. Lint yield levels at both the Ashurst and Thatcher locations were high. Due to poor initial germination, the Kansas Settlement location had to be replanted and was later maturing. Thus, lint yield was down some from the normal average in that area. At the Thatcher location lint yield ranged from 1200 to just over 1600 lbs. lint/acre with ST5242BR producing the highest lint yield and the highest crop value. In Ashurst the yields ranged from 950 to nearly 1350 lbs. lint/acre with Fiber Max FM960RR producing the highest lint yield. However, due to some fiber quality discounts it did not produce the highest crop value. Fiber Max FM989RR had excellent fiber quality and produced the highest crop value even though it produced a slightly lower yield. In Kansas Settlement lint yields ranged from 460 to approximately 850 lbs. lint/acre with the highest lint yield and total crop value being produced by Deltapine DP444BR. This is consistent with the earlier nature of this variety.
    • Arizona Upland Cotton Advanced Strains Testing Program

      Norton, E. R.; Borrego, H.; Ellsworth, K. F.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      A series of experiments were conducted across three locations in Arizona to evaluate over 50 commercial cotton strains. These trials were conducted in Yuma, AZ (130 ft. above MSL); Maricopa, AZ (1170 ft. above MSL); and Safford, AZ (2900 ft. above MSL). Strains were planted in four row plots extending 38 feet in a randomized complete block design with a minimum of three replications. Each location had three commercial cotton varieties included as control treatments for comparison. Data collected on these trials included a series of plant measurements at three growth stages over the course of the season, plus yield and fiber quality data. All data was subjected to statistical analysis to test for differences among strains for yield and fiber quality. Trials conducted at both Yuma and Safford performed extremely well with yields ranging from 1200 to over 2400 lbs. lint/acre. The Maricopa test site experienced some adverse weather (high levels of heat stress) and insect related conditions that led to overall decreased yields. Ranges in yield were from approximately 400 to just over 1600 lbs. lint/acre. Significant differences among lint yield and fiber properties were experienced at every location. Plant measurement results also demonstrated interesting trends among strains and locations.
    • Arizona Cotton Growers Association Breeding Program Preliminary and Advanced Strains Evaluations

      Norton, E. R.; Borrego, H.; Ellsworth, K. F.; Tronstad, Russell; Norton, E. Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2006-07)
      A set of experiments were conducted in two Arizona locations to evaluate preliminary and advanced strains from the Arizona Cotton Growers Association breeding program. These trials were conducted in Yuma, AZ (130 ft. above MSL) and Maricopa, AZ (1170 ft. above MSL). Strains were planted into four row plots extending 38 feet in a randomized complete block design with a minimum of three replications. Each location had three commercial cotton varieties included as control treatments for comparison. Data collected on these trials included a series of plant measurements at three growth stages over the course of the season, plus yield and fiber quality data. All data were subjected to statistical analysis to test for differences among strains for yield and fiber quality. The trial conducted at Yuma performed extremely well with yields ranging from 1300 to over 2100 lbs. lint/acre. The Maricopa test site experienced some adverse weather (high levels of heat stress) and insect related conditions that led to overall decreased yields. Ranges in yield were from approximately 800 to just over 1400 lbs. lint/acre. Significant differences among lint yield and fiber properties were experienced at each location. Plant measurement results also demonstrated interesting trends among strains and locations.