• Progress of Cotton Harvesting in 1987

      Farr, Charles (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Cotton growers began cotton harvest earlier in 1987 than during the previous three years, but they fell behind the other years by December first. Rainfall in late October, particularly November 2, slowed harvest and reduced quality of cotton dramatically in some operations.
    • Natural Resistance of Cotton to Cotton Leaf Crumple Virus

      Wilson, F. Douglas; Brown, Judith K.; Butler, G. D. Jr. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Cultivars and germplasm lines of cotton, Gossvpium hirsutum L., differed in response to infection by the cotton leaf crumple virus (CLCV). The most widely grown cultivars in Arizona and southern California, 'Deltapine 90' and 'Deltapine 61', are susceptible, while ' Cedix', developed in El Salvador, and 'Coral', developed in Nicaragua, are highly resistant or immune. Nineteen other lines from a resistance breeding project in Nicaragua showed highly variable responses.
    • 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.
    • 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.
    • Irrigation Termination of Cotton with Boll Weevil Infestations

      Farr, Charles (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Two irrigation termination trials at Buckeye and two at Laveen determined that irrigation the last four days of August produced as much lint as irrigation seven to ten days later. Pima S-6 and a late planting of DP 90 after oats responded to water in the same way as the early April plantings of Deltapine 77.
    • Response of Texas Root Rot to a Soil Sterilant in Marana in 1987

      Thacker, Gary; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Methyl bromidelchloropicrin, a soil sterilant, was deep-injected into cotton beds ten days before planting. Within the kill areas of the Texas Root Rot, the soil sterilant had some significant effects on the mortality and yield of the cotton.
    • Preplant Zinc Applications to Short Staple Cotton in Marana, 1987

      Thacker, Gary; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      A preplant application of zinc was made to a short staple cotton field where the soil analysis had shown a zinc concentration of 0.64 ppm. No significant yield response was measured.
    • 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.
    • 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.
    • 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.
    • Short Staple Variety Trial, Cochise County, 1987

      Clark, Lee J.; Schwennesen, Eric (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Eleven varieties of short staple cotton, containing four varieties of Acala 1517 (including two new releases from New Mexico State University) were grown near the town of Cochise, which is at an elevation of 4,180 feet and has an average growing season of 232 days. Northrup King's KC 380 (the same as the experimental variety 2019) was the high yielder for the second year in a row, with 954.6 pounds of lint per acre. One of the new Acala' s, 1517-77BR was second in yield, with 936.5 pounds per acre. With the current premium structure, 1517-77BR would produce about $50 more gross farm income per acre than KC 380.
    • 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.
    • 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.
    • Lint Yield of Planting Pima S-6 at Three Dates

      Farr, Charles (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Planting Pima S-6 at 12-day intervals starting April 2 produced more than 70 pounds of lint loss for each delay in planting.
    • Preplant and Pre-harrow Cyanazine (Bladex) Trials

      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 in 1986 and 1987 to measure cotton and weed control response to preplant applications of cyanazine (Bladex) and prometryn (Caparol). Cyanazine was applied in combination with pendimethalin and trifluralin as either preplant incorporated or preharrow treatments. Neither cyanazine or prometryn significantly reduced cotton stands or yields.
    • Field Evaluation of a Presence-Absence, Sequential Sampling Plan for Pink Bollworm Eggs

      Hutchinson, Bill; Stroschein, Debra; Beasley, Bud; Martin, Jeanette; Henneberry, Tom (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      During 1987, a sequential sampling plan for pink bollworm eggs was field-tested in eight 40-acre fields in the Palo Verde Valley, CA. Final analysis of the sequential procedure, including the time necessary to collect and check all bolls, required an average sampling time of 16 minutes/field, approximately a 70% savings over the fixed sample size of 160 bolls/field. Using the sequential plan, the number of bolls examined averaged 46.75/field. The sequential sampling plan error rate for making no-treat recommendations when a field actually required treatment (i.e., actual egg infestation 6%) averaged only 6.4% throughout the season. A final sequential sampling chart, based on the field validation data, is presented.
    • Lint Yield, Earliness and Pink Bollworm Resistance of Cottons Treated with Ethephon and Untreated

      Wilson, F. Douglas; Flint, Hollis M.; Bariola, Louis A. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      An early -maturing, nectariless, okra-leaf germplasm line of cotton, Gossypium hirsutum L., designated WC-12NL, was compared with a full- season, nectaried, regular -leaf cultivar, 'Deltapine 61' (DPL-61) over two locations, Maricopa, Arizona (AZ) and Brawley, California (CA), and two seasons, 1986 and 1987. Half of each plot was treated with ethephon ( =Prep) when the crop was approximately 60% open. Lint yields were higher in WC-12NL than in DPL-61 at AZ, but not at CA. WC-12NL was earlier maturing than DPL-61, but the difference was greater in untreated than in ethephon-treated plots and at AZ than at CA. From 33 to 67% less insecticide was needed to control pink bollworm, Pectinophora gossypiella (Saunders), on WC-12NL than on DPL-61. Pink bollworm infestations were also significantly lower in bolls of WC-12NL.
    • 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.
    • Growth and Development of the Beet Armyworm, Spodoptera exigua, on Carbon Dioxide Enriched Cotton

      Akey, David H. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Growth and development was studied in the beet armyworm (BAW), Spodoptera exigua, reared on cotton seedlings at high (650 ppm) or ambient (325 ppm) carbon dioxide (CO₂) levels and at 2 fertilizer levels. Under high fertilization, female BAW reared on CO₂-enriched seedlings weighed significantly less (873 mg) than controls (101.0 mg) and had a significantly longer developmental time (14.2 vs. 12.4 days for controls). Male BAW followed the same pattern but the data were not statistically significant. Combined (male & female) survival rates for BAW reared on CO₂-enriched cotton seedlings on a high fertilizer level were 19.1 compared to 41.6 % for controls; more females survived than males by a significant ratio of 2:1.