• Effect of Irrigation Termination Date on Defoliation and Yield of Upland Cotton

      Nelson, J. M.; Briggs, R. E.; Hart, G.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      A field study was conducted at the Maricopa Agricultural Center to determine the influence of plant water stress on the effectiveness of defoliants and yield of cotton. Irrigation termination dates of 12 August, 24 August, and 8 September were used to achieve different levels of plant water stress at the time defoliants were applied (22 September). The defoliants tested performed well on cotton, which had termination irrigations in August. Def 6 was not as effective as other defoliants in defoliating plants with an 8 September termination irrigation, unless used in combination with Prep. Cotton with an 8 September termination irrigation produced lint yields 9% higher than cotton with August irrigation termination dates.
    • Effects of Date of Planting on the Lint Yield of Several Cotton Varieties Planted at Four Locations in Arizona, 1988

      Silvertooth, J. C.; Malcuit, J. E.; Howell, D. R.; Else, P.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Field experiments were carried out at 4 locations in Arizona to evaluate the effects of planting date on the lint yield of several varieties of cotton. One pima and eleven upland varieties were planted on 5 dates at 2 locations and 1 pima and nine upland varieties were planted on 5 dates at a third location. At a fourth location, 1 pima and 3 upland varieties were planted on 4 dates. General trends in lint yields indicate an advantage in yield potential from full- season type varieties, particularly when they are planted early. Full-season varieties, however, diminish rather quickly with regard to yield potential, when planting is delayed in comparison to varieties that are considered mid-or shorter-season varieties.
    • Successes and Failures in Foliar Applications to Correct Zinc Deficiency

      Mauney, J. R.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
    • Irrigation Frequency During Fruiting as a Yield Determinant in Upland Cotton

      Radin, J. W.; Mauney, J. R.; French, O. F.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      When cotton is irrigated at long intervals, the root systems become less effective at absorbing water during heavy fruiting, even when the soil is moist. That ineffectiveness, if not counteracted by frequent watering can exaggerate water stress responses during fruiting and promote early cutout. Deltapine 90 cotton was grown at the Maricopa Agricultural Center in 1988 and watered either by daily drip irrigation or by level -basin flooding. In the flood-irrigated plots, various schedules for applying water during fruiting were compared with minimal differences in total water applied. The check treatment (9 postplant irrigations) yielded approximately 2 bales of lint per acre. Small supplemental irrigations on 13 July and 22 July, splitting the normal irrigation cycles, increased yield 45% for only 6% more applied water. Daily drip irrigation in the trials increased yield 63% above the check on 1% more applied water over the season. The results show that flood- irrigated yields can approach drip-irrigated yields without excessive water use, if the irrigation cycle is shortened during fruiting.
    • Strategies to Capture Higher Gross Revenues

      Firch, R. S.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Research on futures price behavior indicates that farmers may find it feasible to use selective hedging or forward contracting to increase gross receipts from the sale of their commodities. University economists have been telling farmers for many years that selective hedging-hedging only in some years rather than all years or no years -- should not be considered as an alternative to hedging every year or never hedging. If selective hedging is to be a feasible strategy for farmers, they must have some system for correctly predicting the direction of futures price changes during the production period in most years.
    • Tierra Prospera Farms CWSI Irrigation Scheduling Demonstration Test

      Garrot, D. J. Jr.; Stedman, S.; Benedict, D. B.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
    • The Effects of Methyl Bromide Fumigants on Verticillium Wilt on Two Varieties of Short Staple Cotton, Safford Agricultural Center, 1988

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Methyl bromid/chloropicrin formulations were applied to strips in the verticillium nursery at the Safford Agricultural Center where two varieties of short staple cotton were subsequently planted. More robust plant growth and reduced incidence of disease were noted with some of the treatments. Yield increases over the check plots were also seen. A study of the residual effects of the treatments will be performed in 1989.
    • Phosphate Sorption of Several Arizona Soils

      Silvertooth, J. C.; Gardner, B. R.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Phosphate (P) adsorption of 6 agriculturally- important Arizona soils was studied by use of adsorption isotherm experiments and with conventional Langmuir and Freundlich adsorption models. Adsorption experiments were conducted at 25°C where each soil was placed in a 10:1 (solution:soil) ratio using 0.01M CaCl₂ as a background solution. Each soil was subjected to 4 levels of inorganic P addition using Ca(H₂PO₄)₂H₂O as the P source. Use of the Langmuir model was significant in all cases (P ≤ 0.05) with r² values ranging from 0.93 to 0.99. Capacity parameter estimates obtained from the models indicated P adsorption potentials of up to 357 lb. acre⁻¹ (818 lb. P₂0₅ acre⁻¹) for the soils studied. Application of the Freundlich model revealed r² values of 0.88 to 0.99 with all models proving to be significant (P ≤ 0.05).
    • Short Staple Variety Demonstration, Graham County, 1988

      Clark, L. J.; Cluff, R. E.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Cotton lint yields in the variety trials in Graham county were higher than the 1987 yields by close to 200 pounds per acre. Two varieties, BR 110 and NK KNX 111 (now KC 311) yielded more than DP 90 at the Thatcher site, the highest yield being 1,569 pounds of lint per acre. In Eden, DP 90 was the highest yielding variety with 1,237 pounds of lint per acre. The New Mexico acalas didn't yield as much lint per acre as the top yielding varieties, but with 1988's premium, produced substantial income per acre. In Thatcher the highest yielding acala produced $861 per acre compared with BR 110's $910, whereas in Eden the highest yielding acala produced $736 per acre against DP 90's $717.
    • Variety and Date-of-Planting Test

      Pegelow, E. J. Jr.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Three upland cotton varielies--Stoneville 506, Deltapine 20, and Deltapine 77--were planted on 4 dates in 1988 at the Maricopa Agricultural Center and observed for flowering boll opening and lint yield. Results from the 1988 studies and those from similar tests in 1985-1987 are being used to determine the relationship of accumulated heat units to the timing of key stages in crop development.
    • Application of Zinc Chelate and Ammonium Sulphate Supplements: Increased Damage to Cotton Foliage from Beet Armyworm and Cabbage Looper

      Akey, D. H.; Flint, H. M.; Mauney, J. R.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Foliar applications of zinc as a chelate or sulphate with ammonium sulphate to plots of cotton resulted in beet armyworm infestations with leaf damage that was 2.3 to 3.1 times greater than that in control plots.
    • Pima Cotton Genetics

      Percy, R. G.; Turcotte, E. L.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Seed increase of 104 accessions and data collection on 65 accessions were obtained in 1988 to further the maintenance and evaluation of the Gossypium barbadense L. germplasm collection. In a program of conversion of tropical non flowering cottons to a day-neutral flowering habit, 63 accessions were advanced 1 generation by backcross. A systematic screening of the G. barbadense collection for bacterial blight resistance involving 200 accessions from 21 countries yielded 8 accessions resistant to races 1, 2, 7, and 18 of the pathogen. Genetic inheritance and linkage investigations of a male sterile and a foliar mutant progressed. An investigation of the geographic and taxonomic distribution of the ovate leaf trait was concluded with negative results. The frequency of the 2 mutant genes ov₁ and ov₂ proved to be too rare to yield meaningful taxonomic or geographic information about the species. Preliminary results from a performance evaluation of interspecific hybrid cottons conducted at Maricopa and Safford AZ, indicated strong environmental influences on hybrids, but generally favorable yield earliness and plant height data were obtained from the higher -elevation Safford location.
    • Comparison of Irrigation Termination Dates on the Yield of Upland and Pima Cotton

      Silvertooth, J. C.; Terry, L. I.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Field experiments were conducted in 1988 to begin an assessment of both the agronomic and entomological implications from differences in irrigation termination dates imposed on both upland and pima cotton. Nine study sites were established with non-replicated treatment arrangements. Two replicated experiments were established at Marana, AZ on both upland and pima comparing early and late irrigation terminations. The upland (DPL 20) field was planted 26 April 1988 and irrigation terminations of 18 August (early) and 5 September (late) were imposed. The pima S-6 field was also planted 26 April and irrigation was terminated on 13 August (early) and 1 September (late). Yield measurements showed no significant differences (P ≤ 0.05) between early or late termination with the DPL 20, but quite substantial and significant differences were observed between treatments in the pima experiment.
    • Short Staple Variety Demonstrations, Pinal County

      Malcuit, J.; Stedman, S.; Silvertooth, J.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
    • Response of Cotton to Various Fertilization Histories

      Hofmann, W. C.; Else, P. T.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Effects of various fertilization histories on cotton yield were investigated for the fourth consecutive year in the same field at the Maricopa Agricultural Center. Treatments included: 1) no fertilizers added for the past 4 seasons, 2) aggressive nitrogen fertilization in the 1988 season, no fertilization for the previous 3 seasons, 3) standard nitrogen fertilization in 1988 similar treatment for the previous 3 seasons, 4) aggressive nitrogen fertilization in 1988 same history as treatment #3 for previous 3 seasons, and 5) a commercial alternative fertilization program (BioHumaNetics, Inc.). Yields in 1988 were significantly different with treatment 2 having the highest yield followed by treatments 3 and 4, followed by treatment 5; treatment 1 had the lowest yield.
    • Final Irrigation Timing of Upland and Pima Cotton

      Farr, C.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Irrigation termination trials were continued in 1988 to evaluate a newer, popular upland variety and pima S-6. Irrigation in the first week of September increased the yield of a May planting of DP 77, but not of two trials in 1988 with early April planting dates. A March planting of pima S-6 failed to respond to a 10 September irrigation on Coolidge sandy loam.
    • Hormonal Changes in Relation to Cutout

      Guinn, G.; Brummett, D. L.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Experiments were conducted in 1987 and 1988 to determine whether hormonal changes may be involved in the decreases in growth and boll retention commonly referred to as cutout. Nitrogen deficiency decreased the auxin content and growth of fruiting branches. The auxin contents of fruiting branches, squares, and bolls decreased during the season as the plants entered cutout. ABA in bolls increased slightly, but the ABA content of squares and fruiting branches showed no consistent changes. The results indicate that decreases in auxin (IAA) may be involved in cutout.
    • The Probability of Temperature Thresholds for Defoliation

      Farr, C.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      The probability of favorable temperatures for some cotton defoliants decreases importantly in the month of October. More effective and earlier defoliation is crucial to advancing the cotton harvest to reduce rainfall damage and diapausing boll weevil numbers. Probabilities indicate more defoliation should be carried out earlier.
    • Effects of Banded Phosphorus Fertilizer on Cotton

      Silvertooth, J. C.; Doerge, T. A.; Thacker, G. W.; Stedman, S. W.; Malcuit, J. E.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Four field experiments were established in 1988 in Arizona to evaluate the effects of banded phosphorus (P) fertilizers on cotton. 2 sites involved upland cotton (Gossypium hirsutum L.) and 2 sites with pima (G. barbadense L. var Pima S-6), with 1 of each located near Marana, AZ (Vinton Anthony sandy loam). A site with 1 of each kinds was also located near Coolidge, AZ (Mohall sandy loam). At the Marana studies, P was applied 6 inches directly below the zone of seed placement at the time of listing and at the Coolidge sites, P was applied 6 inches below and 2 inches to the side of the zone of seed placement after listing but before planting. In all cases, the P source was 10-34-0 at rates of 0, 30, and 65 lb. P₂O₅ acre⁻¹. At the Marana location, a treatment of banded 10-34-0 at 30 lb. P₂O₅ acre⁻¹ plus a foliar application of 10 lb. P₂O₅ acre⁻¹ (early bloom) as 10-34-0 was included in both the upland and the pima experiments. Plant measurements for plant height, flower numbers, node numbers, boll numbers, and nodes to first fruiting branch were taken to evaluate plant response throughout the season. Plant tissue samples were also taken for leaf petiole PO₄-P and leaf blade total P analysis. Lint yield measurements were also taken. No statistically significant (P < 0.05) differences were found among any of the treatments for any of the measured parameters, except in the petiole PO₄-P levels from the upland study at Coolidge on the second sampling date.
    • Profenofos as an Ovicide for Heliothis spp. In Short Staple Cotton and Comparison of the Ovicidal and Commercial Efficacy of Profenofos and Two Tank Mixes

      Dick, G. L.; Moore, L.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)