• Agronomic Comparison of Transgenic Varieties with their Parent Lines, Safford Agricultural Center, 1998

      Clark, Lee J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      As more transgenic varieties become available, grower=s interests intensify and more information is needed to satisfy the inquiries. Agronomic comparisons of six lines (transgenic varieties and their recurrent parents) from three companies are represented in this high desert study. Results show some subtle differences between the transgenic lines and their recurrent parents. Under the high Pink Bollworm pressure observed in the trial, yield increases were uniformly seen when the Bt gene was present, even though all plots were sprayed to control insect pests. Yields tended to be lower when herbicide resistence was introduced into the plants (even though not statistically significant), except when placed in a stacked array. Several agronomic values and HVI lint quality values are reported in this report.
    • Agronomic Evaluations of Transgenic Cotton Varieties, 1998

      Silvertooth, Jeffrey C.; Norton, Eric R.; Silvertooth, Jeff; University of Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Several field experiments were conducted in many of the cotton growing areas of Arizona in 1998 for the purpose of evaluating agronomic characteristics of many new transgenic Upland cotton varieties. In many cases, the new transgenic lines were compared directly with their recurrent (nontransgenic) parents. Evaluations were carried out by collecting plant mapping data from each variety on a regular 14 day interval throughout the season and relating the resultant information to established baselines for Upland cotton in Arizona. Lint yield measurements were also taken on each variety at all locations. Results indicate that all transgenic lines tested are very similar to their recurrent parents in terms of growth, development, and yield. Some subtle differences were noted but they were very slight and should not impact management of the varieties significantly in comparison to their recurrent parents.
    • Arizona Upland Cotton Variety Testing Program, 1998

      Silvertooth, Jeffrey C.; Norton, Randy; Clark, L.; Walser, R.; Husman, Stephen H.; Knowles, Tim; Moser, H.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Ten field experiments were conducted in major cotton growing areas of Arizona in 1998 for the purpose of evaluating Upland cotton varieties in terms of adaptability and performance. Eight commercial cottonseed companies participated in the program. A maximum of two varieties were submitted by each company at each location. Experiments were conducted on a commercial level on grower-cooperator fields in most cases. Locations used in the program spanned the range of conditions common to cotton producing areas of the state from about 100 ft. to 4,000 ft. elevation. Each of the participating seed companies offer a compliment of varieties that can serve to match various production strategies commonly employed in the state. The 1998 cotton season was a very difficult one for many cotton producing areas in AZ below ~2,000 ft. elevation, characterized by a cool wet spring, late planting, a delayed crop, and a strong monsoon season that reduced fruit retention in many cases. Many varieties commercially available performed well at several locations demonstrating good adaptation to Arizona conditions.
    • Cotton Defoliation Evaluations, 1998

      Silvertooth, Jeffrey C.; Norton, Eric R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      A field experiment was conducted near Marana, AZ in 1998 to evaluate the effectiveness of a number of defoliation treatments on Upland (var. Stoneville 474) cotton.. All treatments consisted of materials commercially available in Arizona. Results reinforce general recommendations regarding the use of low rates (relative to the label ranges) under warm weather conditions and increasing rates as temperatures cool. Defoliation treatments of Ginstar alone did a satisfactory job of defoliation and regrowth/topgrowth contol and were very similar to Dropp + Def combination treatments. Adding Prep to Ginstar in this experiment did not improve defoliation or topgrowth control.
    • Cotton Fertility Study, Safford Agricultural Center, 1998

      Clark, Lee J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Three different nitrogen fertilizer regimes were practiced in this study along with an unfertilized check. The same amount of nitrogen fertilizer was sidedressed in the plots in one, two or three applications. No significant differences were seen, but the trends looked like the split applications might have had some advantage.
    • Date of Planting by Long Staple and Short Staple Variety Trial, Safford Agricultural Center, 1998

      Clark, Lee J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Four varieties each of Long Staple and Short Staple cotton were tested over four dates of planting in this study. The first date of planting for the Long Staple cotton was delayed to the 3rd of April because of poor weather earlier. The latest planting was May 13th. Cultivars of differing maturities were tested for both long and short staple cotton to determine their optimal planting time. Many agronomic and hvi values were evaluated to determine the effect of different planting dates.
    • Defoliation of Pima Upland Cotton at the Safford Agricultural Center, 1998

      Clark, Lee J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Nine defoliation treatments were applied to Pima and upland cotton to compare the treatment effects on percent leaf drop, trash sent to the gin, lint yields, percent lint turnout and percent first pick. All of the treatments were beneficial to leaf drop compared to the untreated check with the Ginstar treatments generally performing better than the others. The addition of nonionic surfactants and drift retardants seemed to reduce the activity of Ginstar. Yield differences on long staple treatments were notices and discussed in the paper.
    • Defoliation Tests with Ginstar at the Maricopa Agricultural Center in 1998

      Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Defoliation tests were conducted on upland and Pima cotton at the Maricopa Agricultural Center to evaluate the use of low rates of Ginstar for preconditioning cotton, several rates of Ginstar and tank mixes of Ginstar and Def. The upland cotton used in this test was generally difficult to defoliate, probably because of cool night temperatures. One application of Ginstar + Def gave acceptable defoliation of upland cotton 14 days after treatment (DAT) and this treatment was as good as using Ginstar as a preconditioner followed by Ginstar (2 applications of defoliant). For Pima cotton, most Ginstar treatments gave acceptable defoliation 7 DAT. Although defoliation treatments caused some leaf desiccation, it was not a serious problem in these tests. All defoliation treatments resulted in excellent control of terminal regrowth for both upland and Pima cotton.
    • Development of a Yield Projection Technique for Arizona Cotton

      Norton, Eric R.; Silvertooth, Jeffrey C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      A series of boll measurements were taken at numerous locations in cotton producing areas across Arizona in 1998 in an attempt to continue to develop a yield prediction model with a project that began in 1993. Results from 1995 showed the strongest relationship between final open boll counts and yield compared to a number of other measurements. Based on these results, data collection on boll counts began in 1996 and has continued in 1997 and 1998. Boll counts were taken as the number of harvestable bolls meter-1. All boll count measurements were made within one week of harvest. Number of bolls per unit area were then correlated to lint yield and an estimate for the number of bolls per area needed to produce a bale of lint was calculated. Estimates using all three years data combined indicate that approximately 38 bolls meter-1 are needed to produce one bale of lint per acre.
    • EUP Evaluation of a Novel Insecticide for Lygus Control

      Ellsworth, Peter C.; Deeter, Brian; Whitlow, Mike; Silvertooth, Jeff; The University of Arizona, Department of Entomology & Maricopa Agricultural Center; Rhône-Poulenc Company, Fresno, CA; Arizona Cotton Research & Protection Council (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Lygus became the number one pest of cotton in 1998 with statewide losses of over $16 million in spite of individual costs to the grower of over $55/A for control. Selective technologies for whitefly and pink bollworm control reduce the number of broad spectrum sprays that incidentally control Lygus. Control of Lygus depends mainly on just two related chemical classes of insecticides, organophosphates and carbamates. Over reliance on such a limited diversity of chemical controls increases the risk of resistance. Further, FQPA threatens the future availability of many of our main stay chemical controls. The study reported here sought to investigate the commercial suitability of a new compound, Regent®, for the control of Lygus. This novel mode of action represents one of the few potential new tools under development for Lygus management. Under a federal Emergency Use Permit (EUP), Regent was tested against two standards of Lygus control (Orthene® and Vydate®) and an untreated check. In a test of unusually high Lygus densities, Regent provided excellent control of small (instars 1–3) and large (instars 4–5) Lygus nymphs and may provide marginally better control of adults than current standards. None of the tested agents provided quick control or knockdown of adults. Rather, adult levels were reduced over time, most likely as a result of prevention of the development of new adults via nymphal control. All three materials protected cotton producing yields significantly higher than the check. The Orthene treatment had the highest yield, though not significantly higher than the Regent treatment which was effectively sprayed one less time than the other compounds.
    • Evaluation of a Feedback Approach to Nitrogen and Pix Applications, 1998

      Norton, E. J.; Silvertooth, Jeffrey C.; Norton, Eric R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      A single field experiment was conducted in 1998 at Marana, AZ to evaluate a scheduled (based upon stage of growth) versus a feedback approach (based upon growth parameters and crop conditions) to nitrogen (N) and mepiquat chloride (PixTM) applications on upland cotton (Gossypium hirsutum L.). The parameters used in evaluating feedback applications for both N and Pix included fruit retention (FR) levels and height to node ratios (HNRs) with respect to established baselines for cotton grown in the desert Southwest. Scheduled and feedback Pix applications were made for a total of 1.5 and 2.5 pint Pix/acre, respectively, with the feedback treatments receiving a late season application at approximately 3100 heat units after planting (HUAP 86/550 F threshold). Scheduled Pix treatments received a single 1.5 pint Pix/acre application prior to peak bloom (approximately 2000 HUAP). Scheduled applications of fertilizer N totaled 205 lbs. N/acre from three applications. Feedback applications of N received a total of 100 lbs. N/acre from two applications. Treatments consisted of all combinations of feedback and scheduled applications of both N and Pix. The highest lint yields occurred in the treatment consisting of Pix feedback and N feedback (treatment two), however, there were no significant differences (P≥0.05) among any of the treatments with respect to yield.
    • Evaluation of a Foliar Applied Seed Bed Calcium Soil Conditioner in in Irrigated Cotton Production System

      Griffin, J. R.; Silvertooth, Jeffrey C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      A multi-site experiment was conducted at Paloma Ranch, west of Gila Bend in Maricopa County and at Wellton in Yuma County Arizona. NuCotn 33B was dry planted and watered-up on 28 April 1998. Various rates of application of nitrogen (N) and calcium (Ca) from CN-9 [9-0-0-11Ca (5Ca(NO₃)₂•NH₄NO₃•10H₂O)] was used to evaluate the check. The CN-9 was applied as a foliar application directly to the seed bed on 27 April 1998. Treatment 1 was the check plot that received no CN-9. Treatment 2 received a 12 gal./acre application of CN-9 while treatment 3 received a 15 gal./acre application of CN-9. Each gal of CN-9 weighs approx. 12.2 lbs. and contains 1.1 lbs. of N and 1.4 lbs. of Ca. Treatment 2 received a total of 13 N/acre while treatment 3 received a total of 17 N/acre via CN-9. Treatment 1 received only farm standard applications of UAN-32. Treatments 2 and 3 each received farm standard applications of UAN-32 after the application of CN-9 for continued crop N needs. A total of 17 lbs./acre of Ca was applied to treatment 2 and 21 lbs./acre of Ca was applied to treatment 3. No significant differences were found among the various treatments in terms of plant growth, soil water content, ECₑ values, and sodium absorption ratios. Lint yields were not significantly different (P<0.05).
    • Evaluation of an Acid Soil Conditioner in an Irrigated Cotton Production System

      Griffin, J. R.; Silvertooth, Jeffrey C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      A single field study was conducted on a sodium-affected soil at the University of Arizona’s Maricopa Agricultural Center (MAC) in 1998. NuCotn 33B was dry planted and watered-up on 5 May 1998. Two treatments were evaluated; treatment 1 received no acid and treatment 2 received water-run acid applications. The acid used in this evaluation was sulfuric acid (H₂SO₄). The acid was applied at approximately 11 gallons acid/acre at each scheduled irrigation throughout the entire growing season. All other agronomic inputs and decisions were uniformly applied to both treatments in the same manner throughout the season. The experiment was arranged in a randomized complete block design with two treatments and six replications. Significant differences were found among the two treatments in terms of plant growth and soil water content (P<0.05). Lint yields were significantly different (P=0.0013) with the check having the highest yield.
    • Evaluation of Chemical Controls of Lygus hesperus in Arizona

      Ellsworth, Peter C.; Silvertooth, Jeff; The University of Arizona, Department of Entomology & Maricopa Agricultural Center (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      When other means fail to avoid damaging levels of an insect pest population, chemical control becomes necessary. Chemical control is a variable farm input which should be optimized to reduce economic damage by the pest while maximizing profit and minimizing exposure to secondary pest outbreaks, pest resurgence, and risks of insecticide resistance. To best balance these needs, a grower or PCA needs the best information possible for selecting and timing chemical controls. This study examines the array of Lygus chemical control options currently available as well as experimental compounds that may or may not be available in the future. While identifying the best chemical controls is the major objective of this study, insights into proper timing and duration of control are also discussed. In short, there are few, yet effective, Lygus insecticides available to growers currently. However, with proper rates and timing, significant yield protection can be achieved with Orthene® or Vydate®. To a lesser extent, Thiodan® (endosulfan) was also effective against Lygus, though higher rates than used in this study may be necessary to achieve acceptable control. The use of mixtures did not enhance control of Lygus over our two standards (Orthene or Vydate). Newer compounds were also studied; however, Mirids (plant bugs) are not worldwide targets for development by the agrochemical industry. Thus, most new compounds are effective on some other primary pest (e.g., whiteflies, boll weevil, thrips, aphids), and control of Lygus is merely a potential collateral benefit. Of these, the chloronicotinyls (e.g., Provado®, Actara®) were not practically effective against Lygus hesperus, in spite of their existing or pending labelling. Their labels are based on demonstrated efficacy against a related species present in cotton outside of the West (Lygus lineolaris). One compound shows excellent promise as a Lygus control agent, Regent® (fipronil). Under development by Rhône- Poulenc, this insecticide provides as good or better protection against Lygus than our best materials. In a system demanding multiple applications to control chronic Lygus populations, Regent could be key to the development of a sustainable use strategy that does not over rely on any single chemical class. None of the insecticides tested significantly controlled adult Lygus, except after repeated use and time. Even then, this effect was likely the result of generational control of the nymphal stage which thus produced fewer adults over time. Nymphal control was excellent for Orthene, Vydate, and Regent. Yields were up to five times higher in the best treatments relative to the untreated control. Other effects were also documented for the best treatments which have additional positive impact on grower profitability: shorter plants (better defoliation), higher lint turnouts, less gin trash, and a lower seed index.
    • Evaluation of Planting Date Effects on Crop Growth and Yield for Upland Cotton, 1998

      Norton, Eric R.; Silvertooth, Jeffrey C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      A field study was conducted in 1998 at the University of Arizona Marana Agricultural Center (1,974 ft. elevation) to evaluate the effects of three planting dates on yield and crop development for three Upland varieties. Planting dates ranged from 9 April to 28 May and 342-885 heat units accumulated since Jan 1 (HU/Jan 1, 86/55o F thresholds). Crop monitoring revealed early season fruit loss leading to increased vegetative growth tendencies with all three planting dates. General trends also showed decreasing lint yield with the later dates of planting for all varieties. The more determinate variety (STV 474) was able to set and a fruit load more rapidly than the other varieties in this study at several dates of planting, which resulted in higher yields.
    • Evaluation of the Effects Added Nitrogen Interaction on Nitrogen Recovery Efficiency Calculations

      Norton, Eric R.; Silvertooth, Jeffrey C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Two studies were conducted in 1996 and 1997 at the University of Arizona Maricopa Agricultural Center (MAC) to evaluate the added nitrogen interaction (ANI) or ‘priming effect’ on the determination of nitrogen recovery efficiencies (NRE). The method employed was to compare NRE’s as calculated by two different methods; the difference technique and the isotopic technique. The difference in NREs observed between the two methods indicates the extent of an ANI. Results demonstrated no statistical differences between NRE’s calculated by the two methods. Therefore, no ANI was observed in the field. These results indicate that the less expensive method of calculating NREs (difference technique) is sufficient under irrigated cotton production systems in the desert Southwest.
    • Fertility Management and Calibration Evaluations on Upland and Pima Cotton

      Thelander, A. S.; Silvertooth, Jeffrey C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Various field experiments were conducted during the 1997 and 1998 cotton season involving macro and micronutrient fertilization. A total of six experiments were conducted at various locations in Arizona. Each of the field experiments studied the effects of different nutrients and nutrient combinations on both Upland and Pima varieties. The purpose of these experiments were to evaluate University of Arizona fertility guidelines with respect to soil test results and to possibly fine-tune or calibrate these guidelines for common Arizona soils and cotton growing regimes. Results from these experiments based on soil test information, quantitative plant measurements, and lint yield showed no significant difference due to treatments for all the studies except for a phosphorus study conducted in Graham County.
    • How to Obtain Cotton Advisories from the Internet

      Brown, P.; Russell, B.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Weekly advisories developed by the Arizona Cotton Advisory Program are now available from the Internet. Nineteen location-specific advisories are developed each Monday morning and then transferred to the Main AZMET Internet Web Page located at URL address http://ag.arizona.edu/azmet. To retrieve advisories from the Internet users must 1) log on to the Internet using the procedures required by your Internet service provider; 2) enter the URL for the Main AZMET Web Page; 3) move to the Cotton Advisory sub-page; and 4) select the advisory of interest. Advisories for the most recent week, this year to date, and all of 1998 are available at this Internet address.
    • Integrated Morningglory Control Strategies: Transgenic Cotton and Precision Cultivation

      Knowles, Tim C.; McCloskey, Bill; Wakimoto, Vic; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      A field demonstration was conducted in Mohave Valley to compare cotton morningglory control programs that combined the use of over the top herbicides Roundup Ultra on Roundup Ready cotton (Deltapine 436 RR) or Staple on non-transgenic cotton (SureGrow 125) with and without precision cultivation.
    • Late Season Nitrogen Fertilizer for Cotton

      Knowles, Tim C.; Watson, Jack; Wakimoto, Vic; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1999)
      Field experiments were conducted during the 1996 and 1997 growing seasons in Mohave Valley to determine the effect of late season nitrogen (N) fertilizer applications on top crop yield potential of upland cotton. A long season production system utilizing late season nitrogen (N) applications through peak bloom (August) was compared to a short season production system in which N was applied through mid-bloom (June). Mid-season N applications were based on UA guidelines utilizing plant mapping and petiole nitrate data for the short season production system.