• Selecting for Cotton Seedlings Under Cool and Saline Conditions

      Hofmann, W. C.; Else, P. T. (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      A breeding program aimed at increasing the ability of long and short staple cotton strains to emerge in saline soils under cool springtime soil conditions has now completed the second cycle of selection. Cycle II emergence results show evidence of progress.
    • Effect of Calcium Nitrate and Calcium Chloride on the Primary Root Growth of Cotton Seed Imbibed at Low Temperatures

      Lehle, Fredric; Hofmann, W. C.; Guhy, Bonnie (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      The effect of various concentrations of calcium nitrate and calcium chloride on the primary root (radicle) growth of cotton seed at a suboptimal temperature was evaluated 14 days after imbibition onset under laboratory conditions. Both forms of calcium at concentrations up to 10 mM enhanced cotton seed radicle growth at 15 C.
    • Application of Systemic Fungicides Through Subsurface Drip Irrigation for Control of Phymatotrichum Root Rot

      Olsen, Mary W.; George, Steven; Heathman, Stanley (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      Application of two systemic fungicides, propiconazole (Tilt) and triadimenol (Summit), through subsurface drip irrigation resulted in a significant reduction in the number of dead plants in a Phymatotrichum-infested cotton field. The percent reductions in Tilt treatments were 72% in 1985 and 66% in 1986 and in Summit treatments were reduced 90% in 1985 and 70% in 1986.
    • Drip Irrigated Cotton Responses to Fertilizer Levels, Varieties and Plant Population

      Stroehlein, J. L.; Hofmann, W. C.; Michaud, C.; Scheuring, E. P.; Knowles, T. C. (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      Three cotton cultivars (DPL 41, 90 and 775) were planted at 3 seeding rates (5, 10 and 20 lbs/A). These variables were evaluated under 5 fertilizer treatments which included increasing nitrogen levels and one treatment with nitrogen (N), phosphorus (P), potassium (K) and zinc (Zn). Residual soil N was high and variable and no clear response to applied N was found, although generally higher yields were found with the high N rate. The plots receiving P, K and Zn yielded less than plots receiving an equal amount of N. Increased seeding rates significantly increased yields which was probably an effect of early weed competition. Delta Pine 90 produced significantly more than 41 which was greater than 775. Petiole and soil nitrate values reflected the high and variable available soil N.
    • Scheduling Irrigations on Cotton Based on the Crop Water Stress Index

      Garrot, Donald J. Jr.; Fangmeier, Delmar D.; Husman, Stephen H. (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      The Crop Water Stress Index (CWSI) was used to schedule irrigations on drip irrigated cotton research plots in Tucson and on eight acre furrow irrigated fields at the Marana and Maricopa Agricultural Centers. Scheduling irrigations when plots reached 0.30 CWSI units resulted in highest yields with 1403 lbs/acre cotton lint using 33.8 inches of water. The Marana and Maricopa fields yielded 1322 lb/acre on 28 inches and 1767 lb/acre on 58 inches of water, respectively.
    • The Effects of Cotton Leaf Crumple on Greenhouse-Grown Cotton Incoulated at Five Growth Stages

      Mihail, J. D.; Brown, J. K.; Nelson, M. R. (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      The effects of cotton leaf crumple disease on components of yield and on symptom expression were examined for cotton inoculated at five growth stages. As a result of virus infection, the total leaf area was reduced and significant reductions in yield were observed, regardless of plant age at time of inoculation. Yield reductions resulted from a smaller number of bolls set and/or a decrease in boll weight. Foliar symptoms were associated with plants inoculated at all five growth stages, but were observed sooner and were more severe for plants inoculated at the 2-3, 5-8, and 8-10 leaf stages than those inoculated at the 14-16 or 18-20 leaf stages.
    • Effects of PREP on Cotton Fruiting, Boll Opening and Boll Weevil Populations

      Henneberry, T. J.; Meng, T.; Deeter, B.; Price, P.; Western Cotton Research Laboratory; Union Carbide (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      Prep applied to cotton on 15, 23, and 29 September reduced numbers of squares, immature green bolls < 1 inch in diameter, and accelerated mature boll opening. Reduced cotton fruiting forms in Prep- treated plots resulted in reduced boll weevil population development.
    • Regional Variety Test

      Fisher, W. D.; Pegelow, E. J. (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
    • A New Egg Sampling Plan for Pink Bollworm Reduced Insecticide Use by 35 Percent

      Hutchinson, Bill; Beasley, Bud; Henneberry, Tom; Martin, Jeanette; Western Cotton Research Laboratory; Cooperative Extension, University of California (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      During the past two years we developed an egg sampling plan for the pink bollworm (PBW) to provide a more accurate index of moth (target stage) activity than conventional larval sampling. The plan requires that only the presence or absence of eggs laid on bolls be determined to decide when insecticide treatments are needed. Our objective in 1986 was to determine whether egg sampling vs. conventional treatment criteria (e.g., larval infestations, trap catches of male moths, and /or fixed -spray intervals) provided more optimal timing of insecticide applications in a 640-ac field test. Implementation of the egg sampling method in 8 of the 16 fields resulted in an average 35 percent seasonal reduction in insecticide use when compared to conventional methods. Despite the reduction in insecticide use, PBW larval infestations were not significantly different (P = 0.45) in fields samples for eggs vs. fields sampled for larvae from June to September. Yields were also not significantly different (P = 0.40) between the two sets of fields.
    • A Predictive System for Disease Incidence of Black Root Rot of Cotton

      Mauk, P. A.; Hine, R. B. (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      A quantitative technique has been developed to assay cotton soils for populations of Thielaviopsis basicola, a soil occurring fungus that causes the seedling disease of cotton known as Black Root Rot. The procedure utilizes a soil dilution technique with a carrot extract agar containing etridiazol, Mystatin, streptomycin sulfate, chlortetracycline, calcium carbonate and PCNB. Populations of the fungus have been monitored from April to December, 1986 in a heavily infested Pima S-6 field in cooperation with Bob Cockrill, a Coolidge grower. When field soils containing approximately 600 propagules of the fungus per gram of air dry soil were planted to Pima S-6 in the laboratory, 75-100% and 50-75% cortical decay occurred at 20 and 28 C, respectively. This seedling damage was related to subsequent reduced seedling vigor.
    • Thiocarbamates for Selective Control of Purple Nutsedge in Arizona Cotton

      Heathman, E. Stanley; Chernicky, John P.; Farr, Charles; Stedman, Sam (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      Purple nutsedge Cyperus rotundus is an important weed in cotton (Gossypium spp.) production in Arizona. It is estimated that 15% of the crop acreage is infested. The technology available for selective control of purple nutsedge is not adequate and the infestation level of this weed is increasing. In 1986, the thiocarbamate herbicides, vernolate (Surpass), EPTC (Eptam, Genep) and butylate (Swan +, Genate plus) were evaluated as preplant and postemergence incorporated applications for selective control of purple nutsedge in cotton. There were 25 different trials conducted in Arizona cotton fields. Butylate was more selective to seedling cotton than EPTC and vernolate but all were capable of unacceptable cotton injury. Where preplant irrigations require every furrow irrigation, this concentrated the thiocarbamates in the seed row and resulted in less selectivity. Preplant treatments controlled purple nutsedge for 1 or 2 postemergence irrigations. Postemergence applications were most effective following preplant treatments but were not consistent in controlling nutsedge season -long. This research indicates that purple nutsedge lowered yields only when the cotton was stunted in growth by severe early season infestations. Wherever cotton established dominance over the weeds, yields were not affected. Preplant applications of butylate, if carefully adjusted for the growing conditions, can provide early season control of purple nutsedge.
    • Irrigation and Nitrogen Effects on Plant Hormones, Boll Retention, and Growth of Fruiting Branches

      Guinn, Gene; Brummett, Donald L.; Western Cotton Research Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      An experiment was conducted in Phoenix in 1986 to determine effects of water and N deficits on ABA and IAA concentrations in young bolls and their abscission zones in relation to boll retention, and to determine the effects of N on growth of fruiting branches through the season. Water deficit decreased boll retention, decreased the concentration of free IAA in bolls and their abscission zones, and increased ABA in bolls and abscission zones. But, the concentration of ester IAA increased with water deficit (in contrast to free IAA). Because ester IAA resists degradation during stress, it may facilitate recovery when stress is relieved and some of it is converted to free IAA. N-deficiency symptoms were mild and did not appear early in the season. N had no effect on the ABA and IAA contents of bolls and their abscission zones, and had only a small effect on growth of fruiting branches. The N test is to be repeated in 1987 when N deficiency should be more severe.
    • Drip Irrigated Cotton Responses to Water Level, Varieties and Plant Population

      Hofmann, W.; Stroehlein, J.; Michaud, C.; Else, P.; Dahlberg, J. (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      Three cotton cultivars (DPL 41, 90 and 775) were planted at 3 seeding rates (5, 10 and 20 lbs/A). These variables were evaluated under 5 drip irrigation treatments, which included 23.3, 25.7, 28.0, 30.7 and 31.4 inches of water applied over the growing season. There were 3" of precipitation over the growing season. Only the lowest irrigation level showed significantly reduced yields. DPL 90 had superior yields as compared to DPL 775, with DPL 41 having an intermediate response. The 10 lb/a seeding rate resulted in higher yields as compared to the other 2 rates.
    • Lint Yield of Four Seed Qualities of Stoneville 825 Upland Cotton Planted at 3 Locations, 3 on Planting Dates and at 3 Planting Rates in Arizona in 1986

      Kittock, D. L.; Hofmann, W. C. (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      Low quality Stoneville 825 seed produced reduced stands and, in most cases, reduced lint yields when planted at 3 dates and 3 planting dates at 3 locations in Arizona. Reduced lint yields were explained by reduced stands. Highest lint yield was obtained from the second plantings, 24 and 21 April at Marana and Safford, respectively.
    • Whitefly Adults in Okra-Leaf and Normal-Leaf Cotton

      Wilson, F. D.; Butler, G. D. Jr.; Western Cotton Research Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      The sweet potato whitefly, Bemisia tabaci (Gennadius) continues to be a serious pest of cotton and an important vector of several virus diseases of fall vegetables. In our search for resistant germplasm, we counted adult whiteflies on cotton cultivars and breeding stocks in AZ and Israel. At Maricopa (MAC), seven of 19 cottons had significantly fewer whiteflies than the check, 'Stoneville 825'. Five of the seven were okra-leaf and two were normal-leaf cottons. In another experiment at MAC, an okra-leaf cotton did not have fewer whiteflies than a normal-leaf one. At several locations in Israel, the okraleaf cotton, BD-12, had significantly fewer whiteflies than a number of normal-leaf cottons.
    • Pink Bollworm Resistance and Lint Yield of a Nectariless, Okra-Leaf Germplasm Line

      Wilson, F. Douglas; Flint, Hollis M.; Western Cotton Research Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      A nectariless, okra -leaf germplasm line of cotton, Gossvpium hirsutum L., designated WC-12NL, was compared with a nectaried, regular leaf commercial cultivar, 'Deltapine 61' (DPL-61) at two locations, Maricopa, AZ and Brawley, CA. At Maricopa, two and three insecticide applications were required for control of pink bollworm, Pectinophora gossypiella (Saunders), on WC-12NL and DPL-61, respectively. At Brawley, six and nine applications were required. Lint yield of WC-12NL was 30% higher than that of DPL-61 at Maricopa, while at Brawley, lint yields were about equal.
    • Short Staple Variety Trial, Cochise County, 1986

      Clark, Lee J.; Young, Deborah (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
    • Cotton Variety Observations, Safford Agricultural Center, 1986

      Clark, Lee J.; Thatcher, L. Max (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
    • High Yielding Short Season Cotton Production in Arizona

      Tollefson, Scott (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
    • Lint Yield of Several Cotton Varieties Planted on 5 Dates at 3 Locations in Arizona in 1986

      Kittock, D. L.; Hofmann, W. C. (College of Agriculture, University of Arizona (Tucson, AZ), 1987-03)
      There were some wide variations in cotton variety performance at five planting dates among locations and years. However, on an average, DP 90 and DP 77 performed best when planted between 28 March and 24 April. Stoneville 506 and DP 50 averaged best for May plantings and DP 20, Stoneville 112, and DP 50 averaged best for early June plantings.