• 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.
    • 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.
    • 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.