• Planting Date and Susceptibility to Pink Bollworm

      Brown, P.; Silvertooth, J.; Moore, L.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      The susceptibility of cotton to spring emergence of pink bollworm (PBW) was evaluated for a variety of planting dates in Pinal, Maricopa, LaPaz and Yuma counties using historical climate records and heat - unit -based models that predict PBW emergence and cotton development. Early planted cotton proved most susceptible to the PBW emergence, however, springtime weather conditions also played an important role in determining overall susceptibility. Growers wishing to incorporate planting date as one aspect of PBW management should keep abreast of early season weather conditions.
    • Cotton Variety Trial, Safford Agricultural Center, 1990

      Clark, Lee J.; Carpenter, Eddie W.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Forty four short staple varieties and Pima S-6 were grown in a replicated trial on the Safford Agricultural Center in Graham county. Most of the varieties were commercially available in the cotton belt, however, a few experimental varieties from the New Mexico acalas, ChemBred and from Delta Pines were included. Seventeen varieties produced more than 4000 pounds of seed cotton per acre with the top variety, BR 110, yielding 4921 pounds per acre. The second variety, HS Sal 10, is a new variety developed by Bill Salmons. 1990 contained some record breaking high temperatures in the month of June which were detrimental to yields in other parts of the state. In this area, this heat spell was not as devastating and in some respects this year was a better cotton year than even 1989.
    • Defoliation of Pima Cotton, 1990

      Silvertooth, J. C.; Husman, S. H.; Thacker, G. W.; Howell, D. R.; Winans, S. S.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Five 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. Variable conditions were encountered among the experimental locations in 1990 for treatment comparisons. However, it appears that consistencies in the effectiveness of several treatments for Pima defoliation offer a basis for recommendations across the state.
    • Short Staple Variety Trial, Cochise County, 1990

      Clark, Lee J.; Schwennesen, Eric; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Seven New Mexico acala varieties and one non-acala short staple variety were evaluated for yield and other agronomic variables. 1517-88 produced the most seed cotton but HS 46, the non-acala produced slightly more lint. Both varieties yielded slightly less than three bales of lint per acre. Yields of most of the varieties in the trial were 100 to 200 pounds less than in the previous year. It is felt that the yield reductions were probably more due to lack of heat units during the growing season than the heat spell in June.
    • Comparative Development and Reproduction of Pink Bollworm on Upland and Pima Cotton Cultivars

      Naranjo, Steven E.; Martin, Jeanette M.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Development and reproduction of pink bollworm were studied in relation to four cotton cultivars. Larval developmental times were shortest on pima cotton and longest on a resistant okra-leaf variety (WC-12NL). Prepupal and pupal developmental times were generally unaffected by cultivar. Larval establishment and survival did not differ significantly among cultivars. Female moths laid fewer eggs on pima bolls early in the season and fewer eggs on the okra-leaf cultivar on a season -long basis in comparison with two conventional upland cultivars. Fecundity of adults from the four cultivars varied little but was generally highest in adults from larvae reared on pima cotton. Results have implications for predicting pink bollworm phenology and population development in different cultivars.
    • Water Stress Effects on Upland Cotton Lint Yields Using Infrared Thermometry to Schedule Irrigations

      Husman, S. H.; Garrot, D. J. Jr.; Moore, M.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      The Crop Water Stress Index (CWSI) was used to schedule irrigation on D + PL 90 cotton on a large scale commercial basis in Waddell, Az. The test consisted of sixteen one acre surface irrigated plots. There were four treatments with four replicates arranged in a randomized complete block design. Highest lint yields were attained when irrigations were scheduled at 0.28 CWSI units.
    • Short Staple Variety Demonstration, Maricopa Agricultural Center, 1990

      Malcuit, J. E.; Silvertooth, J. C.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      A short staple variety trial was conducted on the demonstration farm, at the Maricopa Agricultural Center in 1989. Nineteen varieties, received from various seed companies, were entered into the test. Yields ranged from 829 to 1428 lbs. lint acre⁻¹ for STY 110 and STV 1324 respectively. Results from the statistical analysis showed significant differences among varieties. Those varieties that were medium to short - season maturity types yielded higher than long, full season maturity types. This difference in yield was most probably due to the hot and humid weather conditions experienced in the 1990 growing season and the varietal differences associated with heat tolerance.
    • Laboratory Tests Designed to Improve Cotton Planting Seed Quality

      McDaniel, Robert G.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      A number of representative seed lots of both upland and Pima cotton cultivars and experimental strains have been evaluated utilizing two instruments which measure relative seed coat strength. Seed coat strength was found to have a strong genetic component of determination, with relatively minor influence of environment and year of production being observed Greater seed coat strengths should contribute to the relative resistance to seed damage and cracking during picking ginning and conditioning operations. It may be possible to incorporate this trait into cotton cultivars by mass selection techniques.
    • Aflatoxin Contamination: Variability and Management

      Cotty, Peter J.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Mapping aflatoxin contamination in the field reveals that most toxin occurs in relatively few, highly contaminated, bolls. Several studies suggest that protection of early bolls from pink bollworm damage will eliminate many of these highly contaminated bolls. Early harvest will also help reduce aflatoxin contamination. However, the crop must still be carefully managed after harvest because toxin content of mature bolls can increase very rapidly.
    • Cotton Yields as Affected by Pheromone Treatments for Pink Bollworm

      Sears, John; Hood, Larry; Moore, Leon; Winans, S. Sherwood; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Cotton fields treated with Gossyplure pheromone for pink bollworm, Pectinophora gossypiella (Saunders), management were surveyed to evaluate the effectiveness of the pheromone treatments. Fields were randomly chosen within four separate areas of the Parker Valley and Palo Verde Valley and sampled weekly for presence of pink bollworm (PBW ) larvae. No differences were found in cotton yields between fields treated with pheromone and non- treated fields.
    • Comparison of Three Irrigation Scheduling Methods and Evaluation of Irrigation Leaching Characteristics

      Scherer, Tom; Slack, Don; Watson, Jack; Fox, Fred; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Three methods were used to schedule irrigations during the 1990 growing season on replicated plots at the Maricopa Ag Center using DPL 90 cotton. This is the final report of the research initiated in 1988. The three methods were: a soil water balance model based on historic consumptive use curves (ERIE), a soil water balance model (AZSCHED) based on the Modified Penman Equation and daily weather (AZMET), and infrared thermometry using the Crop Water Stress Index (CWSI). A potassium- bromide conservative tracer was applied at selected sites in the plots to evaluate leaching characteristics. The irrigation scheduling test was again duplicated at the Safford Experiment Station and is presented in another report. Results from this years data indicate that there was no significant difference in yield between the 3 methods. Also, there was no significant difference in the amount of applied irrigation water. The AZSCHED and ERIE methods will be developed into Extension educational tools and released for use by growers.
    • Short Staple Variety Demonstration, Pinal County, 1990

      Malcuit, J. E.; Stedman, S.; Silvertooth, J. C.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Short staple variety trials were conducted for three years at Prechel Farms near Coolidge At. Six varieties were included in 1988, twelve in 1989, and eight in 1990. Results from the statistical analysis showed significant differences among varieties in each of the three tests. Lint yields ranged from 908 to 1313 lbs. lint acre⁻¹ in 1988, 2844 to 4827 lbs. seedcotton acre⁻¹ in 1989, and 695 to 1059 lbs. lint acre⁻¹ in 1990. Those varieties that were medium to short-season maturity types yielded higher than long season maturity types in the 1988 and 1990 seasons. The reverse was true in the 1989 season.
    • Pima Cotton Genetics

      Percy, R. G.; Turcotte, E. L.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      An isozyme study of the diversity and structure of Goss_vpium nii revealed levels of genetic variation within the species which were high for an island endemic. Infraspecific diversity of G. darwinii was observed among populations of the various Galapagos Islands. Evidence of introgression of other Gossypium species into darwinii was noted. An investigation into the effects of altered Pima (G. barbadense) fiber genotypes on interspecific hybrid fiber characteristics indicated that parent genotype could significantly affect hybrid fiber length, strength, uniformity, and micronaire. However, hybrid heterosis for fiber length and micronaire greatly exceeded the influence of parent genotype. Hybrid fiber characteristics were unique, fitting within neither the extra -long staple nor long staple classifications. A conversion program to convert photoperiodic short-day accessions of a Gossvpium barbadense germplasm collection to day neutrality continues.
    • Basic Cotton Crop Development Patterns

      Silvertooth, J. C.; Brown, P. W.; Malcuit, J. E.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Summaries of cotton crop phenology, as a function of heat units (HU, 86/55°F limits) have been developed across a wide range of production conditions in Arizona. Optimum ranges in HU accumulations since January 1 are used to describe planting dates to maintain optimum yield potentials with full season varieties. Basic events such as the occurrence of pinhead squares, squares that are susceptible to pink bollworm, and first bloom are described in terms of HU accumulations since planting. Also, the expected ranges of HU's accumulated since planting that are required to accomplish crop cut -out are shown for three general maturity types of Upland cotton.
    • Uptake and Reside of 3, 4-Dichloro-5-Isothiazole Carboxylic Acid in Cotton Plants and Soils Under Field Conditions

      Bartels, P. G.; Olvey, J.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      DICA (3, 4-dichloro-5-isothiazole carboxylic acid) is being used as a chemical hybridizing agent in the cotton breeding program of Chembred Seed Company. This compound produces male sterile flowers. Registration of this compound by EPA requires that a plant residue study be conducted to provide data on the quantitative amounts of residues in F₁ plants and seeds, F₂ seeds and in the soil. This study was carried out in Arizona because the hybrid F₂ cotton seeds will be grown in Arizona.
    • Pima Cotton Improvement

      Turcotte, E. L.; Percy, R. G.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Pima experimental strains P67, P69, P71, P73, P74, and Pima S -6 were grown in Regional tests at 11 locations across the Pima belt in 1990. P73 averaged highest in mean yield across locations followed by P74, P69, P67, Pima S-4 and P71. The experimental strains, in comparison with Pima S-6, had longer, stronger, finer, and more whitish fiber. Experimental strains P45, PSI, P53, P62, P66, and EIS were released jointly by the USDA ARS and the Arizona Agricultural Experimental Station, and registered in Crop Science.
    • Effect of Plant Nitrogen Status on Effectiveness of Defoliants for Short Season Cotton Production

      Nelson, J. M.; Hart, G.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      A field study was conducted at the Maricopa Agricultural Center to determine the influence of nitrogen fertility level on the effectiveness of defoliants for short-season cotton production. Increasing the nitrogen fertility level from 30 to 130 lbs N/A decreased lint yields from 3.2 to 26 bales /A. High residual soil N favored the use of a low N fertility rate. Defoliation treatments were most effective at the 30 lbs. N/A fertility level. Increasing the application rate of Dropp from 0.2 to 0.4 lbs. a.i./A increased the percent defoliation. There was a significant linear decrease in the effectiveness of defoliants as the petiole NO₃-N content increased from 300 to 7000 ppm.
    • Irrigation Scheduling on Long and Short Staple Cotton Safford Agricultural Center, 1990

      Clark, L. J.; Carpenter, E. W.; Scherer, T. F.; Slack, D. C.; Fox, F. Jr.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Three irrigation scheduling techniques are compared on both long and short staple cotton in replicated small plot trials on the Safford Agricultural Center. The Erie method uses historical evapotranspiration data developed in the Mesa area but mathematically adjusted for the elevation in Safford and incorporated in a computer spreadsheet. The AZSCHED method is a near real -time irrigation scheduling program using AZMET weather date, a modified Penman equation and heat unit based crop coefficients to calculate water deficits. This program will schedule irrigations on up to 60 fields. The third method utilizes infrared thermometry to determine crop water stress indices from foliage temperatures, ambient temperature and relative humidity. This latter method was used to track the crop stress throughout the growing season on all treatments. All three methods were considered successful for both long and short staple cotton with the Erie method yielding higher than the other two for both types of cotton. Further refinements will be made on the AZSCHED method until it performs at or above the Erie method
    • Microplitis sp. From Australia (Hymenoptera: Braconidae): Development in the Beet Armyworm and Adult Longevity in Relation to Temperature

      Butler, G. D. Jr.; Henneberry, T. J.; Silvertooth, Jeff; Bantlin, Marguerite; USDA ARS- Western Cotton Research Laboratory, Phoenix AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      The effects of temperature on development and longevity of a Microplitis sp. from Australia on the beet armyworm, Spodoptera erigua (Hübner) was studied in the laboratory. Time of development ranged from 25 days at 15°C to 6.2 days at 27.5 °C. The parasite developed twice as fast as its beet armyworm host. Average longevities of male and female parasites were not significantly different.
    • Field Performance of Cotton Genetically Modified to Express Insecticidal Protein from Bacillus thuringiensis

      Wilson, F. Douglas; Flint, Hollis M.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Five transgenic lines of cotton, Gossypium hirsutum L., carrying the delta-endotoxin gene from Bacillus thuringiensis Berl., and two control cultivars, Coker 312 (the parent stock) and MDS1N (an adapted nectoriless line) were evaluated at the Maricopa Agricultural Centerfor resistance to attack by several insect pests and for agronomic properties. The transgenic lines were highly resistant to pink bollworm (PBW), Pectinophora gossypiella (Saunders), as shown by 90% fewer rosetted blooms, 96% fewer PBW recovered from incubated bolls, and 92% less seed damage than in the control cultivars. The transgenic lines were highly resistant to saltmarsh caterpillar, Estigmene acres (Drury), and beet annyworm, Spodoptera exigua (Hbn.), as shown by minimal damage to transgenic leaves and almost complete defoliation of control leaves. The transgenic lines were virtually immune to cotton leafperforator, Bucculatrix thurberiella Busch as shown by no apparent damage to transgenic leaves, and many mines, "horseshoes", and feeding areas on the control leaves. Compared to Coker 312, one transgenic line yielded more lint, and one yielded less. Four transgenic lines had higher lint percentages and all five had smaller bolls and were later maturing than Coker 312. Compared to MD51N, no transgenic line yielded more lint and one yielded less. All five transgenic lines had lower lint percentages, three had smaller bolls, and three were earlier maturing than MDS1N (USDA, ARS, Western Cotton Research Laboratory in cooperation with Monsanto Co. and Arizona Agricultural Experiment Station).