• The 1995 Arizona Cotton Advisory Program

      Brown, P.; Russell, 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), 1995-03)
      Arizona Cooperative Extension generates and distributes weather -based Planting Date and Cotton Development Advisories for 11 cotton production areas (Marana, Laveen, Paloma, Litchfield Pk., Pinal Co., Parker, Mohave Valley, Queen Creek, Safford, Yuma Valley, and Aguila). 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 1994 and growers may obtain the advisories by mail or fax from the local county extension office, and by computer from the AZMET computer bulletin board. Improved normal weather statistics and the addition of an advisory for Cochise County are the main changes planned for the 1995 program.
    • Cotton Defoliation Evaluations, 1993

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Two field experiments were carried out in representative cotton producing areas of Arizona to evaluate the effectiveness of a number of defoliation treatments on Pima cotton. These experiments were conducted at Coolidge and Marana. The treatments employed principally consisted of relatively new materials available in Arizona, and were compared to current standard treatments. All treatments showed promise in terms of effectiveness and the results provide a basis for use recommendations in 1995.
    • Defoliation of Pima and Upland Cotton at the Safford Agricultural Center, 1994

      Clark, L. J.; Carpenter, E. W.; Odom, P. N.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Experiments were effected on both Pima and upland cotton to compare the defoliation effects of different rates of Ginstar, Ginstar + Prep and sodium chlorate with an untreated check. Weather conditions after treatment applications were recorded and observations taken after one week and two weeks. Grab samples were taken from the picker to determine percent trash and to run HVI analyses.
    • Defoliation Research on Upland and Pima Cotton at the Maricopa Agricultural Center in 1994

      Nelson, J. M.; Hart, G. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Field studies were conducted at the Maricopa Agricultural Center to evaluate the effectiveness of selected defoliation treatments on Pima and upland cotton under warm and cool weather conditions. Air temperatures were high for tests conducted on 16 and 22 September and cool for tests conducted on 14 October. In September tests, Pima cotton was more susceptible to leaf desiccation after applications of defoliants than upland cotton. Single applications of Ginstar or Dropp + Def gave good defoliation in September tests. In October, Pima cotton was effectively defoliated by chemical treatments but a single application of defoliants did not provide acceptable defoliation of upland cotton.
    • Development of a Yield Projection Technique for Upland and Pima Cotton

      Norton, E. R.; Silvertooth, J. C.; Unruh, B. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A series of boll measurements were taken at two locations in 1994 on 5 different varieties in an attempt to develop a yield prediction model. Measurements were taken in strip plot variety trials at Maricopa Agricultural Center and Marana Agricultural Center over a period of approximately 2 months from peak bloom through cut-out. Measurements taken included boll weight, boll diameter, bolls/meter, plants/meter, and final yield from each specific measurement area. Stepwise linear regression resulted in a yield prediction model expressing yield as a function of heat units accumulated after planting, boll diameter or boll weight, and bolls/meter.
    • Does a Preharvest Application of Roundup® Improve Cotton Defoliation?

      McCloskey, William B.; Husman, Stephen H.; Silvertooth, Jeff; Department of Plant Sciences, University of Arizona, Tucson, Arizona; Cooperative Extension, Maricopa County, Phoenix, Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Preharvest applications of Roundup improved defoliation and regrowth suppression when used in conjunction with an application of Dropp +Def on Upland cotton in experiments conducted in Buckeye, Maricopa, and Queen Creek, AZ. However, all treatments used provided commercially acceptable defoliation. Preharvest Roundup applications made about two weeks (or one irrigation interval) before the application of Dropp +Def did not reduce seed cotton yields, lint yields, or affect color-grade and fiber characteristics.
    • Effect of Combinations of Accelerate and other Defoliants on Defoliation and Yield of Pima and Upland Cotton

      Nelson, J. M.; Hart, G. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Field studies were conducted at the Maricopa Agricultural center to evaluate the effectiveness of Accelerate when used in combination with other defoliants. In addition, an experimental compound was tested as a boll opener. Air temperatures were very high at the time these tests were conducted and most defoliant treatments caused desiccation of Pima leaves 7 days after treatments were applied. Several treatments did result in acceptable defoliation of Pima cotton 14 days after application. In the upland test, Ginstar used alone resulted in higher defoliation percentages than any combination of defoliants. Boll opener treatments had no effect on boll opening of Pima or upland cotton. In these tests, there were no differences among treatments in lint yield or fiber properties.
    • Effect of Plant Water Status on Defoliation of Pima Cotton

      Nelson, J. M.; Hart, G. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A study was conducted at the University of Arizona Maricopa Agricultural Center, Maricopa, AZ in 1994 to determine the influence of plant water status at the time of defoliation on effectiveness of defoliants and yield of Pima cotton. Several irrigation termination dates were used to achieve different levels of plant water stress at the time defoliants were applied. A single application of defoliants did not provide adequate defoliation under the conditions of this test. The earliest irrigation termination date resulted in the highest defoliation percentage. High CWSI values at the time defoliants were applied were related to the highest defoliation percentages, but were not necessarily related to satisfactory defoliation. The CWSI appears to have limited value as a guide to determine when to defoliate Pima cotton.
    • Effect of Planting Date on Yield of Upland and Pima Cotton Varieties at Marana

      Unruh, B. L.; Silvertooth, J. C.; Brown, P. W.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A single field experiment was conducted at Marana Agricultural Center (2000 fl elevation) to evaluate the response of one Pima (G. barbadense L) and two Upland (Gossypium hirsutum L.) cotton varieties to three different planting dates. Planting dates ranged from 12 April to 16 May. In general there was decreasing lint yield with later planting dates.
    • Plant Population Evaluation for Upland Cotton

      Norton, E. R.; Silvertooth, J. C.; Stedman, S. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Plant population management is an important aspect of cotton production. Recommendations for optimum plant densities range from 25,000 - 45,000 plants per acre (ppa). A study was conducted in Pinal county in 1994 to evaluate the recommendations already given. Plant densities for this study ranged from approximately 18,000 - 65,000. Yields increased with populations of 18,000, 28,000, and 39,000 ppa. For populations of 43,000 and 65,000 ppa a corresponding decrease in yield from 39,000 ppa was observed. This study serves to reconfirm the recommendations for optimum plant densities.