• 1993 Parker Valley & Mohave Valley Short Staple Cotton Variety Trial

      Hood, L. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Two short staple cotton variety trials were conducted in the Colorado River Basin. One trial was located in the Parker Valley and one in the Mohave Valley. Ten varieties from various seed companies were entered in each test. Yields varied considerably among varieties and locations. However, these trials among others provides evidence that current variety choices are viable components of Arizona cotton production.
    • 1994 Cottonseed Treatment Evaluations

      Norton, E. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Cottonseed was treated with several fungicide treatments in an effort to protect the seed and seedling from disease. Seed germination and vigor was evaluated in three Arizona locations; Maricopa, Marana, and Safford. Stand counts were taken on two separate dates after emergence at both Safford and Marana and once at Maricopa and percent emergence was calculated. Among the three locations two, Marana and Safford, showed significant differences among treatments. Treatment number 5 placed first at both locations where significant differences were found. The untreated control placed last in the ranking at both Marana and Safford for all dates of sampling.
    • 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.
    • 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.
    • 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.
    • 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.
    • Effect of Soil and Foliar Applied Potassium on Pima and Upland Cotton at Two Arizona Locations

      Galadima, A.; Silvertooth, J. C.; Unruh, B. L.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Due to increasing emphasis and interest being placed on cotton (Gossypium spp.) fiber quality as well as yield benefits associated with potassium (K) fertilization, two studies were conducted in 1994. These studies with those before them were aimed at assessing the agronomic necessity of K fertilization in Arizona cotton production. The locations of the trials included Maricopa Agricultural Center (Casa Grande sandy loam) and Safford Agricultural Center (Pima clay loam). At the Safford location, both Upland (G. hirsutum L., var. DPL 90) and Pima (G. barbadense L., var. S-7) cotton were planted with treatments that included both soil and foliar K applications. The trials at Maricopa Agricultural Center included four foliar K applications over the growing season on Pima (G barbadense L., var. S-7) cotton. The results of the experiments at both locations indicated no lint yield responses to K fertilization by either Upland or Pima cotton.
    • Evaluation of a Feedback Approach to Nitrogen and Pix Application

      Silvertooth, J. C.; Norton, E. R.; Unruh, B. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A single field experiment was conducted in 1994 at Maricopa, AZ to compare a scheduled approach (based on stage of growth) versus a feedback approach (based on vegetative status) to both nitrogen (N) and mepiquat chloride (PIX™) applications on Upland cotton (Gossypium hirsutum L.). PIX feedback treatments were based upon fruit retention (FR) levels and height: node ratios (HNRs) according to established baselines. Scheduled PIX applications were made for a total of 1.0 pt./acre over two applications, with feedback PIX treatments receiving a single 0.5 pt./acre application near peak bloom (approx. 2200 heat units after planting (HUAP), 86/55 °F threshold) Scheduled applications of fertilizer N totaled 225 lbs. N/acre from four applications and feedback N treatments received a total of 135 lbs. N/acre from three 45 lb. N/acre applications. Treatments consisted of all combinations of scheduled or feedback applications of both N and PIX. The highest lint yields were from a treatment receiving feedback N and PIX and a treatment receiving scheduled N and PIX, which were not significantly differencent (P ≤ 0.05) from one another. From a practical standpoint, however, these treatments were very different in terms of the magnitude in differences of fertilizer N and PIX required to produce comparable yields.
    • 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.
    • Evaluation of Soil Conditioners and Water Treatments for Cotton Production Systems

      Unruh, B. L.; Silvertooth, J. C.; Sanchez, C. A.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Advanced technologies to produce synthetic polymers such as polyacrylamide (PAS, and polymaleic anhydride (PMA) have produced products which may be economically feasible alternatives to traditional treatments such as gypsum in the desert Southwest. In 1994 three field studies were initiated, two identical studies were located in the Yuma Valley and one at Paloma Ranch. At Yuma Valley the experiments included 0, 1, and 2 tons gypsum/acre, over which, various soil-applied treatments were made; including, a check, soluble PMA (Sper Sal™), and PAM (Hydro-Growth™). Upland cotton 'DPL 5461' was grown in both Yuma Valley studies. At Paloma Ranch, Upland 'DPL 5415' planted. Prior to planting, two gypsum applications were made at 0 and 2 tons/acre. Also included as treatments were various methods and rates of Sper Salt™. No differences among treatments were detected in either of these locations relative to crop yield. At Paloma Ranch there were some early-season differences in soil crusting among the various soil amendment treatments, however, these differences dissipated as the season progressed and did not result in lint yield differences.
    • 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.
    • 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.
    • Timing Initial Post-plant Irrigation Based upon Plant-Water Status

      Steger, A. J.; Silvertooth, J. C.; Brown, P. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A two year study was conducted to determine the optimum timing of the initial post plant irrigation using leaf water potential (LWP) measurements. A short - season Upland cotton (Gossvpium hirsutum L.), variety DPL 20, was planted on 19 April 1993 and 15 April 1994 at the Marana Agricultural Center on a Pima clay loam (Typic Torrifluvent) soil. Treatments, designated Tl , 72, and T3, were such that the initial post plant irrigation would be applied when the midday LWP of the uppermost, fully- developed leaf exposed to full sunlight measured -15, -19, and -23 bars, respectively. All treatments received the same irrigation regime following the initial post plant irrigation. Basic plant measurements, including plant height, mainstem node number, fruit retention, number of nodes above the uppermost white bloom, fresh bloom count within a 166 -ft1 area, and percent canopy cover, were taken weekly from each plot. Soil -water data was collected at 10 inch depth increments, to a depth of 60 in. , from access tubes located in each experimental unit. Yields were 1112, 1095, and 977 lbs lint/acre in 1993 and 1082, 1035, and 964 lbs lint /acre in 1994 for T1, 72, and T3, respectively. Yields were reduced when the midday LWP was allowed to fall below -19 bars, however, reduction was significant (P 5 0.05) only in 1993. At the time of the initial post plant irrigation for each treatment, approximately 83, 62, and 32 % of the total plant available water was present in the upper 60 in. of the soil profile for Ti, 72, and T3, respectively.