• The 1996 Arizona Cotton Advisory Program

      Brown, P.; Rusell, B.; Silvertooth, J.; Ellsworth, P.; Stedman, S.; Thacker, G.; Husman, S.; Cluff, R.; Howell, D.; Winans, S.; et al. (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Arizona Cooperative Extension generates and distributes weather -based Planting Date and Cotton Development Advisories for 14 cotton production areas (Marana, Laveen, Paloma, Litchfield Pk., Pinal Co., Parker, Mohave Valley, Queen Creek, Safford, Yuma Valley, Aguila, Cochise Co., Greenlee Co. and Harquahala). Planting Date Advisories are distributed from mid -February through the end of April and stress 1) planting cotton varieties according to heat unit accumulations rather than calendar date and 2) the importance of soil temperature to good germination. Cotton Development Advisories are distributed from early May through mid - September and provide updates on crop development, insects, weather and agronomy. The Cotton Advisory Program will continue in 1996 and growers may obtain advisories by mail or fax from the local county extension office, and by computer from AZMET or the University of Arizona College of Agriculture World Wide Web Page. Major program changes planned for 1996 include 1) adjusting the Crop Development Advisories to reflect the revised legal first planting dates in low elevation production areas and 2) the addition of an advisory for Harquahala.
    • Cotton Defoliation Evaluations, 1995

      Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      A single field experiment was conducted near Coolidge, AZ in 1995 to evaluate the effectiveness of a number of defoliation treatments on Upland cotton (var. DPL 5415). All treatments consisted of materials commercially available in Arizona, and each showed promise in terms of overall effectiveness. Results do provide reinforcement for current defoliation guidelines for Arizona which recommend using low rates (relative to the label ranges) under warm weather conditions, and increasing rates as temperatures cool.
    • Defoliation of Pima and Upland Cotton at the Safford Agricultural Center, 1995

      Clark, L. J.; Carpenter, E. W.; Odom, P. N.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Twelve defoliation treatments were applied to Pima and upland cotton to compare the treatment effects on percent defoliation of the plants, percent first pick values, percent gin trash and any effects they might have on fiber qualities. All of the treatments were beneficial compared to the untreated check, but differences between treatments were small.
    • Defoliation Tests with Ginstar at the Maricopa Agricultural Center in 1995

      Nelson, J. M.; Hart, G. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Defoliation tests were conducted on upland cotton at the Maricopa Agricultural Center to evaluate rates of Ginstar and tank mixes of Ginstar with Def, Prep, and spray adjuvants. In September when temperatures were high, good defoliation was obtained 14 days after treatment using Ginstar at 0.094 lb. a. i./acre. As temperatures cooled in early October, a higher rate of Ginstar was necessary to achieve defoliation. Under very cool temperatures in late October and early November, the tank mix of Ginstar + Def generally improved defoliation over Ginstar used alone. Several adjuvants appeared to improve the effectiveness of Ginstar when temperatures were cool.
    • Development of a Yield Projection Technique for Arizona Cotton

      Norton, E. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      A series of boll measurements were taken at several locations across the state in 1995 in an attempt to develop a yield prediction model. Measurements were taken out of two strip plot variety trials at the University of Arizona Maricopa Agricultural Center and in the Coolidge area, and also out of two commercial fields in Buckeye and Paloma Ranch over a period of approximately 2 months from peak bloom through cut-out. Data analysis revealed a best fit model that included seedcotton yield as a function of boll count, boll size, boll diameter, and heat units accumulated after planting (HUAP). A series of open boll counts were also taken from over 120 experimental units across the state within one week of harvest. The data revealed strongest relationships between final open boll counts and yield.
    • Effects of Combinations of Accelerate and Other Defoliants on Defoliation of Upland Cotton

      Nelson, J. M.; Silvertooth, Jeff; Maricopa Agricultural Center (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Field studies were conducted on upland cotton at the Maricopa Agricultural Center to evaluate the effectiveness of Accelerate when used in combination with other defoliants. In a September test, good defoliation was obtained in seven days using Ginstar or Dropp + Def + Accelerate and in 14 days using Accelerate + Prep. In October, under cooler conditions, no treatment provided acceptable defoliation in 14 days. In both tests, Ginstar used alone resulted in higher leaf drop percentages than Ginstar + Accelerate.
    • Evaluation of Irrigation Termination Management on Yield of Upland Cotton, 1995

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      A single field study was conducted in 1995 at the Maricopa Agricultural Center (1100 ft. elevation) to evaluate the effects of three dates of irrigation termination on yield a common Upland cotton variety (DPL 5415). Planting date was 3 April (469 HU /Jan 1 86/55° F thresholds). Following difficult establishment, crop vigor was generally low all season, with a relatively strong level of fruit retention. Three dates of irrigation termination an -1T3) were imposed based upon crop development into cut -out, with IT1 (21 August) set such that bolls set at the end of the first fruiting cycle would not be water stressed and could be fully matured. The third termination (IT3) date was 22 September, which was staged so that soil moisture would be sufficient for development of bolls set up through the first week of September. The second irrigation termination (IT2, 1 September) was intermediate to IT1 and IT3. Lint yield results revealed a 139 lb. lint/acre difference between IT1 and IT3, which was statistically significant (P < 0.05).
    • Research Note on Effects of Diurnal Temperature Extremes on Cotton Yields at the University of Arizona Maricopa Agricultural Center

      Warren, D. C.; Rauschkolb, R. S.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      An examination of the weather record for the University of Arizona Maricopa Agricultural Center revealed that short staple cotton yields were negatively affected by cool summers. Cool summers are here defined as June through August months with many days having cooler than average max temperatures for those months. No correlation to yield was found for nighttime temperature; nor was there a detectable effect of higher than average temperature affecting yields.
    • Row Spacing Studies, Safford Agricultural Center, 1994 and 1995

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Four varieties (or variety types) were tested over three row spacings in the two years reported in this study. Two barbadense varieties, S6 and S7 or OA 312, and two hirsutum varieties, DP 90 and a NM acala were planted in 30 inch, 36 inch and 40 inch row spacing environments. Optimal row spacing varied by variety over the two years but averaged over the two years, the 36 inch spacing provided the highest yields for all varieties except for the NM acatas.