• Changes in Free and Bound Auxin with Development of Squares and Bolls in Relation to Shedding

      Guinn, Gene; Brummett, Donald L. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Hormone analyses were conducted to determine why large squares seldom shed while young bolls do. Large squares contained five times as much free auxin as flowers, and they contained 16 times as much bound auxin. The high auxin content of large squares is probably a major reason that they almost never shed unless injured (for example, by insects). Free and bound auxin both decreased to very low levels at flowering and remained low for four days thereafter. This low concentration of auxin at, and just after, flowering is probably a major reason that bolls are likely to shed during the week after flowering. Both free and bound auxin increased rapidly between 7 and 9 days after flowering, possibly accounting for the decrease in boll shedding rate at this stage of development. Amide-linked IAA was the major form of auxin in squares, whereas ester IAA (presumably bound to sugars) was the major form of auxin in bolls.
    • Controlling Purple Nutsedge in Fallow Soil with EPTC and Butylate

      Heathman, E. S.; Chernicky, J. P.; Barstow, B.; Farr, C.; Tickes, B.; Howell, D. R. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
    • Cotton Seed Treatment, Greenlee County, 1986

      Clark, Lee J.; DeRosa, Edith (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Six different seed treatments and one in furrow granular treatment were used in a field with a history of black root rot, caused by Thielaviopsis basicola. The treatment was a follow-up on the study done the previous year (1). Stand counts, root lengths and seed cotton yields were taken to see if any of the treatments increased stand counts or stimulated root growth. Thielaviopsis was not isolated in the plants this year, so the effect of the fungicides on this pathogen were not evaluated. Stand counts were, however, significantly influenced by the seed treatments.
    • Cotton Variety Observation, Safford Agricultural Center, 1986

      Clark, Lee J.; Carpenter, Eddie W. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      The check variety, Delta Pine 90, produced more than any of the new varieties in this unreplicated strip test. However, three new varieties produced yields within 10 % of the Delta Pine 90 yields; they were BR 110, Northrup King 111 and Germains GC 365.
    • Cotton Variety Trials, Greenlee County, 1987

      Clark, Lee J.; DeRosa, Edith (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Four short staple variety trials were harvested in Greenlee county in 1987, covering long season varieties, early maturing varieties, acala varieties and a regional variety trial which was duplicated in Cochise county. Germains GC 510 and Delta Pine 90 yielded equally with acala 1517-75 in the long season trial. Delta Pine 20 out-yielded acala 1517-SR1 in the trial of earlier maturing varieties. An experimental acala, B 510, out-yielded the other acalas in the trial, but required more time to produce the yield. Wider experience with this new acala and others in the trials will be necessary before recommendations can be made. The better yielding varieties produced more than two bales of lint this season.
    • Decline in Water Uptake by Irrigated Cotton During Boll Filling, and its Amelioration by Daily Drip Irrigation

      Radin, John W.; Mouney, Jack R.; Kerridge, Peter C. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      In 1984,1985, and 1986, leaf water potentials of irrigated cotton declined markedly as the crop approached cutout. Midday transpiration rates also declined, indicating a water-stressed condition. The water stress occurred despite the fact that measurements were made only when the soil was fully charged with water. In 1986, plant hydraulic conductances were estimated. The conductance was high early in the season, declined to a low value during cutout, and increased during regrowth to the high value of the early season. It is suggested that root length and efficiency of water uptake, or both, decrease during boll filling as most assimilates are partitioned into the bolls. Daily drip irrigation prevented this susceptibility to stress during boll filling. In 1984 and 1986, drip irrigation decreased the length and severity of cutout, resulting in an increased boll load at the end of the season.
    • Defoliation of Pima Cotton

      Silvertooth, Jeff; Howell, Don R. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Afield study was conducted in Yuma County to evaluate the relative effects of a plant growth regulator application and several defoliation treatments on Pima cotton. There were no statistically significant effects recorded with regard to the plant growth regulator application. There was a significant difference among defoliation treatments by analysis of percent leaf drop estimates. Promising results were recorded for DROPP as a defoliant material for Pima cotton under the given test conditions.
    • Development and Validation of a Simulation Model of Pink Bollworm Population Dynamics

      Huntchinson, Bill (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      A process- oriented simulation model of pink bollworm population dynamics in commercial cotton has been developed. The model, written in FORTRAN, is driven primarily by temperature and crop phenology. In addition to key ecological parameters, the model incorporates the impact of multiple insecticide applications. The model is presently being validated and modified for use as an on-line management tool.
    • Douple Cropping with Controlled Traffic Tillage

      Thacker, Gary; Ottman, Mike (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Double cropping barley and cotton, using a system of controlled traffic tillage, was compared to conventionally tilled, full-season cotton. In this test, the yields of the barley and late planted cotton were too low to be competitive with the full season cotton.
    • Effect of Bractedness on Early Season Square Shed Due to Thrips, Frankliniella occidentalis, in Cotton in Arizona

      Flint, Hollis M.; Wilson, F. Douglas; Cutice, Nancy J. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Populations of the western flower thrips, Frankliniella occidentalis (Pergande), were observed in field plots of cotton, Gossypium hirsutum L., Deltapine-61 (DPL-61) and WC-12NL, a nectariless, okra -leaf variety in the DES -56 germplasm line, and in fields of Stoneville-825 (ST-825), DPL-61, and DP -77 in Maricopa, AZ, during June - August 1987. The thrips were collected from plant terminals; square shed was observed on the upper five nodes of plants; and the bractedness (three-bract = normal) of matchhead-size squares was determined from samples of squares picked from the plants and from shed squares beneath the plants. Shed squares were microscopically examined to determine the cause of shedding. Populations of Lygus hesperus Knight were determined from sweep-net samples.
    • Effect of Ethphon (PREP™) on Short Staple Cotton in Marana, 1987

      Thacker, Gary; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Ethephon was applied to Deltapine 55 cotton with 35% of the bolls open. Ethephon significantly increased the percent first pick yield of the cotton. There was no significant difference in the total yield.
    • Effect of Pix on Three Tall Statured Short Staple Cotton Varieties and One Short Statured Cotton Variety, in Graham County, 1987

      Clark, Lee J.; Cluff, Ronald E. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Four short staple cotton varieties were grown with and without an application of PIX to see its affect on their growth, maturity and yield. PIX is a plant growth regulator thatmodifies plant architecture, Two of the tall -statured varieties, Delta Pine 90 and Acala 1517-75, showed increases in lint yield of 5.8 and 13.7%, respectively, coupled with a hastening of their maturity. Stoneville 506, a short- statured, medium- maturing variety was unaffected by the plant growth regulator. A tall, gangly variety, Germains GC 365, was shortened in height and in maturity, but exhibited a small decrease in yield.
    • The Effect of Soil Temperature and Inoculum Levels of Thielaviopsis basicola on Black Root Rot of Cotton

      Hine, R. B.; Mauk, P. A.; Tedla, Tesfaye (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Two planting dates, March 28, and April 28 were used to study the effect of soil temperature during planting on black root rot of cotton. Also, several cotton varieties were evaluated for response to the disease under varying soil temperatures and inoculum levels.
    • Effect of Spray Dilution and Rate of Pix Application on Long and Short Staple Cotton, Safford Agricultural Center, 1987

      Clark, Lee J.; Carpenter, Eddie W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      PIX was applied to long and short staple cotton in 5, 10 and 20 gallons of water in an incomplete factorial design involving 0.5, 1 and 2 pints of the product per acre. Plant heights were significantly shortened and the percent of lint obtained in the first picking was significantly increased when Piz was applied on the short staple cotton. No statistically significant yield differences were observed between the volumes of dilution or the rates of application for either long or short staple cotton. A factor underlying the experiment was that the monsoon rains. They kept the surface of the ground moist and the plants looking good; however, the subsurface moisture had apparently been depleted, and the plants were under some stress. This stressed condition offset what good the FIX might have done for yield.
    • Effects of Sewage Sludge on Cotton Lint Quality

      Day, A. D.; Taylor, B. B.; Pepper, I. L.; Minnich, M. M. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Three field experiments were conducted in Avra Valley, Arizona, in 1986, to compare the lint quality of upland cotton fertilized with liquid sewage sludge with the lint quality of cotton fertilized with commercial inorganic fertilizer. Most lint quality components were similar for cotton fertilized with sewage sludge or inorganic nitrogen. Fertilization of cotton with sewage sludge tended to increase lint yield and decrease lint quality. Fertilization of cotton with sewage sludge increased vegetative growth and delayed lint maturity.
    • Effects of Sewage Sludge on Heavy Metals in Cotton Seed

      Day, A. D.; Taylor, B. B.; Pepper, I. L.; Minnich, M. M. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      In 1987, seed samples from three cotton fields in Avra Valley, Arizona, grown with liquid sewage sludge and inorganic nitrogen fertilizer, were analyzed for five heavy metals. Concentrations of cadmium, copper, lead, nickel, and zinc were similar in cotton seeds fertilized with either sewage sludge or inorganic nitrogen fertilizer. The levels of all five metals were well below the allowable EPA limits.
    • Effects of Two New Dropp™ Formulations on Cotton Defoliation

      Briggs, R. E.; Nelson, J. M. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Two new Dropp formulations show promise as cotton defoliants. In addition to excellent leaf drop, most squares, flowers, and young bolls were also shed, removing the food source for late season insects.
    • Effects of XE-1019 and Pix on Upland Cotton in Arizona, 1987

      Briggs, R. E.; Nelson, J. M. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      The plant regulators XE-1019 and PIX were tested at the Maricopa and Marana Agricultural Centers. Few yield responses were found in 1987, apparently due to the short stature of the crop at both locations.
    • An Evaluation of an Alternative Commercial Fertilization Program for Cotton

      Hofmann, W. C.; Else, P. T. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Plant growth products manufactured by BioHumaNetics, Inc. (BHN) were evaluated at the Maricopa Agricultural Center for the third consecutive year in the same field. Treatments included: 1) no fertilizers added; 2) standard fertilization used on cotton at the farm; and 3) a treatment schedule prescribed by BHN. Yields in 1987 were significantly different; the BHN treatment produced the highest yield, and the unfertilized treatment produced the lowest yield. Yields from all three treatments were substantially lower than corresponding 1986 yields.
    • Factors Affecting the Response of Cotton to Preplant Application of EPTC (EPTAM) and butylate (Sutan +)

      Chernicky, J. P.; Heathman, S.; Hamilton, K. C.; Barstow, B. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Research was conducted at Maricopa, AZ with EPTC (S-ethyl dipropyl carbamothioate) (1.0 lb/a) and butylate (S-ethyl bis (2-methylpropyl)carbamothioate) (2.0 and 3.0 lb/a) in 1986 and 1987 to measure the response of cotton to preplant application methods. Butylate and EPTC were applied as either a preplant incorporated or preharrow treatments. The greatest injury to cotton and poorest weed control resulted when butylate or EPTC were applied on flat ground and incorporated to a depth of 2 inches or 4 to 6 inches. Adequate weed control and minimal injury to cotton was observed when these two thiocarbamates were applied preharrow.