• The 1994 Arizona Cotton Advisory Program

      Brown, P.; Russell, B.; Silvertooth, J.; Ellsworth, P.; Stedman, S.; Thacker, G.; Hood, L.; Husman, S.; Cluff, R.; Howell, D.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      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 (fax only in Yuma County only) from the local county extension office or by computer from the AZMET computer bulletin board.
    • Boll Sampling to Predict Lint Yield in Upland and Pima Cotton

      Unrah, Bryan L.; Norton, E. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Giving a cotton (Gossypium spp.) producer a method to predict lint yield, would be a useful management tool. The objective of this study was to determine if relatively simple measurements could be made near cut -out which could be used to adequately estimate lint yield for Upland (G. hirsutum L.) and Pima (G. barbadense L.) cotton. Data and samples were collected from the nitrogen (N) management study at Maricopa Ag. Center from two N treatments which were imposed on both Upland (var. DPL 5415) and Pima (var. S-7) cotton. The treatments were no added N and N added on an as- needed basis. Twenty hard -green bolls from the first or second fruiting positions were collected from each plot on 19 August 1993. The number of bolls expected to reach maturity prior to crop termination were then determined from five randomly selected plants in each plot. Measurements on each boll collected included fresh weight, diameter, number of locks, number of seeds, and dry seed cotton weight. Plant population was determined from early season stand counts. Seed cotton per boll was most highly correlated to boll weight for DPL 5415 and for Pima S-7 it was most highly correlated with boll diameter. These respective parameters were then used in linear regression to predict seed cotton /boll. Lint yield calculated from the regression models (using boll weight or diameter) and yield calculated from means of the data collected agreed quit well. Predicted yields from regression analysis overestimated the actual Upland yield by about 730 lb lint /acre and under estimated Pima yields to within about 150 lb lint /acre. It appears that this procedure has the potential to estimate lint yields to within about 150 lb lint /acre. However the sampling scheme will he refined especially in regard to estimation of plants /acre and bolls /plant which should improve yield estimate accuracy.
    • Cotton Defoliation Evaluations, 1993

      Silvertooth, J. C.; Stedman, S. W.; Cluff, R. E.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Three field experiments were carried out in several representative cotton producing areas of Arizona to evaluate the effectiveness of a number of defoliation treatments on Upland cotton. These experiments were conducted at Coolidge, Marana, and Safford and utilized defoliation treatments designed for their potential effectiveness finder cooler weather conditions commonly experienced later in the defoliation season and at higher elevations. The treatments employed also offer potentials for use in close proximity to urban areas due to not having offensive odors associated with them. All treatments showed promise in terms of effectiveness and the results provide a basis for use recommendations in 1994 as well further points of study in future experiments.
    • Cultural and Management Practices for Pima Cotton Production

      Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      The good use of cultural or agronomic practices is fundamental to the production of high yields and quality of American Pima cotton. In order for Pima farmers to maintain viable production operations, a continual review and improvement upon the existing set of cultural practices are in order. Basic aspects of crop production such as planting date management, soil fertility and plant nutrition, plant growth regulator use, crop termination, and defoliation are reviewed in this paper in relation to American Pima cotton production. Specific attention is also given to potassium (K) fertility management and Alternaria leaf spot regarding new aspects of potential management needs.
    • Defoliation of Pima and Upland Cotton at the Safford Agricultural Center, 1993

      Clark, L. J.; Carpenter, E. W.; Odom, P. N.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Experiments were effected on both Pima and upland cotton to compare the defoliation effects of Ginstar, Starfire 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 Pima and Upland Cotton at the Marana Agricultural Center in 1993

      Nelson, J. M.; Barney, G. F.; Hart, G. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      A field study was conducted at the Marana Agricultural Center to evaluate the effectiveness of ground rig applied defoliant treatments on Pima and upland cotton under cool weather condition. The experimental defoliant Ginstar and the combination treatment of Dropp + Def resulted in good defoliation 14 days after application.
    • Defoliation Research on Pima and Upland Cotton at the Maricopa Agricultural Center in 1993

      Nelson, J. M.; Hart, G.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      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. Weather conditions during September tests were warm and dry while in late October tests weather was very cool. Defoliation treatments resulted in a high percentage of leaf desiccation in a test on 10 September. Ginstar and Dropp + Def treatments gave good defoliation of cotton in a 23 September test. In October tests, defoliation treatments were effective on Pima cotton but upland cotton as difficult to defoliate. Ginstar defoliant was generally as effective as the Dropp + Def treatment at the rates tested.
    • Effect of Plant Water Status on Defoliation and Yield of Pima Cotton

      Nelson, J. M.; Hart, G. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      A field study was conducted at the Maricopa Agricultural Center to determine the influence of plant water status at the time of defoliation on the effectiveness of defoliants and the yield of Pima cotton. Irrigation termination dates of 3 and 20 September and 8 October were used to achieve different levels of plant water stress at the time defoliants were applied (26 October). A single application of defoliants was not adequate to defoliate the cotton under the conditions of this test. The 3 September irrigation termination date resulted in the highest percentage of defoliation (63 %). CWSI and plant water content (RWC) measurements indicated that the irrigation termination treatments resulted in large differences in plant water stress at defoliation time. There was a significant increase in the percent defoliation as the CWSI values increased from 0.54 to 0.99.
    • Evaluation of Date of Planting on the Yield of Several Upland Varieties at Marana, 1993

      Silvertooth, J. C.; Brown, P. W.; Norton, E. R.; Unrah, B. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      A single field experiment was conducted in 1993 at Marana, Arizona (2,000 ft. elevation) to evaluate the response of three Upland cotton varieties to three dates of planting. Planting dates ranged from as early as 6 April to 11 May. Planting date was a significant effect for all varieties and revealed a substantial drop in yield with delays past 20 April in 1993, which corresponded to 568 heat units (HU, 86/55 °F thresholds) accumulated since 1 January.
    • Plant Population Evaluation for Upland Cotton

      Silvertooth, J. C.; Norton, E. R.; Stedman, S. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
    • Practical Uses of Crop Monitoring for Arizona Cotton

      Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
    • Upland Cotton Variety Resposne to Row Spacing

      Husman, S. H.; Silvertooth, J. C.; Jech, L. E.; Wegener, R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      An Upland cotton row spacing study evaluation 30 in. vs. 38 in. rows was conducted in the Gila Valley of western Maricopa County in 1993. In addition, six Upland varieties were also evaluated on both the 30 and 38 in. row configurations. There were no row spacing differences in yield among five of the six varieties. Sure Grow 1001 had significantly lower lint yields when produced on 30 In. rows. DPL 5415 had significantly higher lint yields that the other five tested varieties on 38 in. rows. There were no variety differences in the 30 in. rows.