• Pima Cotton Improvement

      Percy, R. G.; Turcotte, E. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Pima experimental strains P73, P74, P75, P76, P77, and P78 and the varieties Pima S-6 (PS-6) and Pima S-7 (PS-7) were grown in Regional tests at seven locations across the Pima belt in 1991. When yields were averaged across five test locations below 2,500 feet, the strains P73, P74, P75, and P76 ranked higher than PS-6, but lower than PS-7. At two test locations above 2,500 feet the strains P76 and P73 ranked higher in yield than PS-6 and PS-7. There was a trend across all locations for the strains P73, P74, P75 and P76 to be shorter in height than PS-6. The strain P76, which was the highest yielding strain across all locations, was the shortest strain at five of the seven locations. Strains included in all tests tended to have whiter, stronger fiber than PS-6. The above was not the case for P77 and P78, which were present in only two tests.
    • Effect of PIX (Mepiquat Chloride) on the Growth, Development, and Yield of Pima S-7 (P-69) and Deltapine (90) Cotton

      Bartels, Paul G.; Easley, Jack; Nelson, John; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Plant Growth Regulators (PGR's) are used in cotton production to reduce excessive vegetative growth. This study was conducted to determine the effect of mepiquat chloride (PIX) on growth, and yield of Pima S7 and Deltapine 90 cotton. Single and multiple applications of PIX were conducted over the growing season. Plant mapping measurements were performed 13 times. Seed cotton yield estimates were obtained with a mechanical picker. Analysis of the mapping data showed that vigor index for control and PIX treated Pima and Deltapine plants was linear for the first 9 weeks, then leveled off as flowering and boll set occurred. PIX treated Pima plants were approximately 5cm shorter than the control after the 9th week. Heights of PIX treated Deltapine were similar to the controls. The number of nodes above white bloom in the FIX treated plants was not modified. PIX treatment of Pima cotton reduced the seed cotton yield compared to controls but yield of PIX treated Deltapine was similar to the controls.
    • Use of Treated-vial Technique to Determine Efficacy of Several Insecticides against the Sweetpotato Whitefly, Bemisia tabaci (Gennad.)

      Sivasupramaniam, S.; Kelly, S. E.; Cross, D.; Brown, J.; Watson, T. F.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      A treated -vial technique was used to bioassay insecticide susceptibility of sweet potato whitefly populatons occurring on different hosts and at different locations in southern Arizona. All insecticides tested proved to be efficacious against the sweetpotato whitefly. Combinations improved efficacy, for example, Orthene to Danitol and DEF to Baythroid. Three important factors appeared to affect efficacy: 1) geographic site; 2) host plant of SPWF; and, 3) time of season. Further detailed experimentation needs to be done to elucidate the reasons for this.
    • Dissolved Nitrogen Compounds in Integrated Aquaculture Effluent

      Brooks, George Benjamin Jr.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Integrated aquaculture utilizing pre- irrigation water will hypothetically increase the levels of dissolved nitrogen products in the resulting effluent. Research was performed to assess the levels of additional nutrients added. The results suggest however, that integrated aquaculture may reduce the amount of nitrogen as nitrate applied to the fields.
    • Community-wide Insect Management Program in Pima County, 1991

      Moore, Leon; Thacker, Gary; Watson, Theo; Ellsworth, Peter; Combs, Jack; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      The Marana-Avra Growers' Task Force and Arizona Cooperative Extension worked together to implement a comprehensive, community-wide insect management program. Growers worked in unison to implement a number of Integrated Pest Management techniques; including uniform optimal planting dates, trap cropping, pinhead square spray applications, in-season insect management, and late season management. This strategy focused on the area's primary pest, the pink bollworm (PBW). This program delayed the need to treat for PBW until late August and minimized secondary pest problems. However, research results on the effectiveness of trap crops were inconclusive.
    • Evaluation of Transgenic Cotton Lines for Resistance to Pink Bollworm and Leaf Feeding Lepidoptera

      Wilson, F. D.; Flint, H. M.; Parks, N. J.; Stapp, B. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Four Monsanto transgenic lines of Coker -312 containing the gene for endotoxin from Bacillus thuringiensis were compared to Coker-312 and MD51ne for resistance to the pink bollworm (PBW) and leaf-feeding lepidopterans. In 11 samples of 50 bolls per plot, 12 plots per line, collected 7/16 to 8/24, the transgenic lines averaged 0.13 PBW /100 bolls while the controls averaged 5.92 PBW /100 bolls. None of the bolls collected from the transgenic lines on 11/18 contained diapausing PBW larvae, while the control lines averaged 57 diapausing larvae /100 bolls. The transgenic lines generally had less leaf damage caused by beet armyworm, cabbage looper and saltmarsh caterpillar.
    • Defoliation of Pima Cotton, 1991

      Silvertooth, J. C.; Husman, S. H.; Stedman, S. W.; Brown, P. W.; Howell, D. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Four field experiments were carried out in several representative cotton producing areas of Arizona to evaluate the effectiveness of a number of defoliation treatments on Pima cotton. Somewhat variable but generally hot and dry conditions were encountered among the experimental locations in 1991 for treatment comparisons. It appears that consistencies in the effectiveness of several treatments for Pima defoliation offer a basis for further refinement of recommendations across the state.
    • Leafminers, Liriomyza trifolii, on Cotton in Arizona

      Palumbo, John C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Liriomyza leafminers have occurred in Arizona for several years. It has only been recently that a new species, Liriomyza trifolii, has been reported on vegetable crops such as melons and lettuce. During the 1991 growing season, L. trifolii was observed causing damage to cotton for the first time in Central Arizona. Infestations occurring in Coolidge, had reached damaging levels and required control, whereas populations occurring in Yuma were very low. The impact of management and environmental factors responsible for the outbreaks of L. trifolii on cotton are discussed.