• Plant Growth Regulator Studies at the Safford Agricultural Center, 1994

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Methanol, Cytokin and PGR IV plant growth regulators were tested on long and short staple cotton on the Safford Agricultural Center in 1994. It was a follow up study on Methanol and Cytokin and a first time look at PGR IV.
    • 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.
    • 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.
    • Evaluation of a Leaf-turn Method for Sampling Whiteflies in Cotton

      Diehl, J. W.; Ellsworth, P. C.; Naranjo, S. E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Plans for sampling sweetpotato whiteflies in cotton were evaluated within 8,000 acres of cotton within central Arizona. These plans were found to be a practical and efficient way to track whitefly populations. In general they should add about 8 minutes to a pest sampling regime. Neither time of day nor sampler experience were found to have a significant effect on the number of whiteflies counted. Therefore, this method provides a common currency for growers, PCAs and others to compare whitefly numbers among fields and through time.
    • 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.
    • Short Staple Variety Trials in Cochise County, 1994

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Variety trials were grown at two locations and with two different sets of short staple varieties. One dial on the Robbs farm, north of Kansas Settlement, tested eight acolas varieties from New Mexico and California. The other trial on the Curry farm, southwest of Kansas Settlement and north of Sunsites, tested twelve upland varieties as part of the statewide testing program. The latter trial was grown under drip irrigation. Yields were exceptionally high at these high elevation trials due to the record breaking heat experienced during the summer. Top yielding varieties were Prema in the acala trial and DP 5409 in the upland trial with lint yields of 892 and 1791 pounds per acre, respectively.
    • Practical Considerations of Precision Guidance and Weed Control in Cotton

      Thacker, Gary W.; Coates, Wayne E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      This paper offers practical advice to growers interested in precision guidance technologies. Various types of guidance systems are described, along with their potential applications and benefits in a farming operation. Also discussed are some of the techniques which can be employed with precision guidance, including mechanical removal of weeds in the row, improved nutsedge control, and precision herbicide applications.
    • 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.
    • Irrigation Frequency and Cotton Yield in Short-Season Cotton Systems

      Chu, Chang-chi; Henneberry, Thomas J.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      We tested the hypothesis that small frequent irrigations during the July cotton peak fruiting stage would result in better fruiting and higher cotton yields than the same amount of water applied less frequently. Over three years under a short - season production system, irrigation intervals of every 5-d with 42 mm of water applied at each irrigation increased cotton lint yield by 5-11 % compared to irrigation intervals of 10- and 15-d with 80 and 130 mm of water applied at each irrigation, respectively. The results show that small, frequent furrow irrigations during cotton fruiting are highly effective in reducing water deficit during critical growth stages and improved lint production in a short - season cultural system. Soil salt content in the top 15 cm of soil was not increased after three years of study.
    • Nitrogen Management Experiments for Upland and Pima Cotton, 1994

      Silvertooth, J. C.; Norton, E. R.; Unruh, B. L.; Navarro, J. A.; Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Three field experiments were conducted in Arizona in 1994 at three locations ( Maricopa, Marana, and Safford). The Maricopa and Safford experiments have been conducted for six consecutive seasons, with consistent plot locations; the Marana site was initiated in 1994. The purposes of the experiments were to validate and refine nitrogen (N) fertilization recommendations for both Upland and Pima cotton. The experiments 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. 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 effects of N fertility levels have been consistently evident in crop maturity and its relationship to lint yields.
    • Community-wide Implementation of Samplin and Action Thresholds for Whiteflies in Cotton

      Diehl, J. W.; Ellsworth, P. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Sampling and decision-making plans for managing sweetpotato whiteflies were implemented within 8,000 acres of cotton within the Laveen-Tolleson area of central Arizona. On the average, thresholds utilized for the first whitefly treatment were lower than those recommended, but subsequent treatments were made at about recommended thresholds.
    • 1994 Low Desert Upland Cotton Advanced Strains Testing Program

      Husman, S. H.; Jech, L. E.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Forty eight , non -commercially available advanced strains cotton varieties were tested in 1994 on a commercial farm in Gila Bend, AZ. D &PL 5415 and Sure Grow 501 were included as commercial checks for comparison purposes. Ten participating cotton seed breeding companies entered five lines each of materials which were felt to show promise for potential commercialization. Lines were specifically chosen for their potential for yield performance under low desert environmental conditions. Each plot was six rows wide by 38 feet long replicated four times. The test was planted on April 1, 1994 and harvested on November 17 and November 29, 1994 for both the first and second pick respectively.
    • 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.
    • Short Staple Variety Trial, Greenlee County, 1994

      Clark, Lee J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Nine short staple cotton varieties including five New Mexico acalas, four California acalas were tested in the 1994 variety study. The highest yielding variety was 1517-91 with a lint yield of 1009 pounds per acre. The average yield was nearly 200 pounds per acre higher than the previous three years. In addition to lint yields; percent lint, plant heights, height to node ratios and plant populations are shown. A lint yield comparison for 1991, 1993 and 1994 is included in this paper.
    • Evaluation of Late Season Pix™ Applications

      Norton, E. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      The effects of late -season Palm on the growth characteristics and yield of Upland cotton was examined in this study. Three treatments were imposed late-season (3447 HUAP), 1, a check plot, receiving no Pix™, 2 receiving 0.75 pt/acre, and 3; receiving 1 pt/acre. The imposed treatments did not have a statistically significant effect on plant growth characteristics or earliness nor were there any significant overall yield differences detected among treatments.