• 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.
    • 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.
    • 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.
    • Greenhouse and Field Studies with Plant-Derived Oils for Control of the Sweet Potato Whitefly on Cotton

      Butler, G. D. Jr.; Henneberry, T. J.; Coudriet, D. L.; Broza, M. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Plant derived oils (cottonseed and soybean) in greenhouse and field studies were promising for sweet potato whitefly, Bemisia tabaci (Gennadius) control. Cotton seedlings treated with oil in the greenhouse repelled whiteflies up to 7 days and high mortality of treated larvae, pupae and adults occurred. In the field, application of crude cottonseed oil to cotton with high air-blast, ground spray equipment suppressed whitefly populations thoughout the season.
    • 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.
    • 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.
    • 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.
    • Pest Control Advisors' Recommendations for Cotton Insecticides: A Historical Review

      Baker, Paul B.; Brew, Tasha M. (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      A survey of agricultural pest control professionals showed that certain compounds have consistently been recommended to control cotton pests for more than 40 years. Over that same period, the number of preferred materials available for recommendation has greatly increased. Other trends are toward greater use of compounds using lower application rates and biological insecticides.
    • Pink Bollworm Egg-Larval Survivorship in Cotton Treated with Insecticides

      Hutchinson, Bill; Beasley, Bud; Henneberry, Tom (College of Agriculture, University of Arizona (Tucson, AZ), 1988-03)
      Pink bollworm egg -larval survivorship in insecticide -treated fields averaged (± SE) 19.8% (± 2.3) for the F2 and F3 generations developing during the primary boll producing time of the year (July and August). These observations have been useful in developing a simulation model of pink bollworm population dynamics.