• 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.
    • 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.
    • 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.
    • A Comparison of Three Cotton Tillage Systems

      Coates, Wayne E.; Thacker, Gary W.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Over a three year study, two reduced tillage systems used significantly less energy than conventional tillage. The Sundance system averaged 46% of the energy used by the conventional system, and the Uprooter-Shredder-Mulcher (USM) averaged 65% of the energy used by the conventional system. These energy savings translate directly into cost savings of about the same proportions. Additionally, the Sundance and USM systems can plow down and prepare the next seedbed in about one-half the time that conventional tillage requires. In three years of testing we have not detected any significant differences in soil compaction, and we have not measured any yield reductions from these reduced tillage systems.
    • 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.
    • Control of the Sweetpotato Whitefly by Insect Growth Regulators

      Bartlett, A. C.; Lewis, L. J.; Hunter, B. A.; Silvertooth, Jeff; Bantlin, Marguerite; USDA-ARS-Western Cotton Research Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Two newly developed insect growth regulators were tested at two dose levels for control of the sweetpotato whitefly on cotton. The two chemicals showed some promise for control although the dose rate and application schedules were not optimal and plot sizes were too small to show a decrease in cotton stickiness or sugar content due to the treatments. In these tests a chitin synthesis inhibitor was more effective in controlling immature stages than a juvenile hormone mimic.
    • Cotton Lint Qualities of Varieties Grown in Southeastern Arizona, 1989

      Clark, Lee J.; Carpenter, Eddie W.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      High Volume Instrument (HVI) classing of eighteen cotton varieties grown at several elevations in southeastern Arizona are compared by location in this paper. Data presented herein would indicate that elevation does not affect fiber length nor strength, these factors are more a function of variety and management. Micronaire values were seen to be lower at the higher elevations and this was felt to be a function of lower maturity level because of reduced growing season coupled with production of fine fibered New Mexico acalas. This report also contains HVI values on lint from 47 varieties of short staple cotton grown on the Safford Agricultural Center during the 1989 season.
    • Cotton Response to Mutiple Applications of PIX, 1990

      Silvertooth, J. C.; Malcuit, J. E.; Husman, S. H.; Winans, W. S.; Hood, L.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Three field experiments were conducted in 1990 in Arizona to evaluate cotton crop response to several treatment regimes of multiple applications of PIX (an anti-gibberellic acid plant growth regulator). Treatment regimes used in 1990 employed higher rates of PIX/acre/application and extended times of applications later into the fruiting cycle than earlier experiments in 1988 and 1989. Similar to earlier experiments, results in 1990 demonstrated the ability of some PIX treatments to significantly reduce plant height, relative to the untreated check treatments. The 1990 cotton production season in Arizona consisted of conditions which led to excessive rates of fruit loss and abortion, and somewhat vegetative plants. Final fruit retention levels of 30 to 50% were realized in the three 1990 experiments after a period of fruit loss through July and August. Lint yield results revealed significant differences (P ≤ 0.05) between several selected treatments at only one of the locations in 1990.
    • 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.
    • 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.
    • Cottonseed Treatment Evaluations in Arizona, 1990

      Silvertooth, J. C.; Malcuit, J. E.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Field experiments were conducted at four locations in Arizona (Yuma, Maricopa, Marana, Safford) to evaluate 16 cottonseed treatments on cotton that included 12 on Upland (Q. hirsutum L.) and 4 on Pima (Gossvpium barbadense L.). Stand counts were taken to evaluate the effectiveness of each treatment. Statistical analysis showed no significant differences among the treatments used for the Upland cottonseed. Significant differences were found among the treatments used for the Pima cotton seed at the Marana and Safford locations only.
    • 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.
    • Defoliation Research on Pima Cotton at the Marana Agricultural Center in 1990

      Nelson, J. M.; Silvertooth, J. C.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      A field study was conducted at the Marana Agicultural Center to evaluate the effectiveness of selected defoliation treatments on Pima cotton under cool weather conditions. Defoliants were slow acting at this location, probably due to cool night temperatures and dry field conditions. The combination Dropp + Def 6 + Accelerate gave good defoliation results 18 days after application. The experimental defoliant SN 597 NA 243 shows promise as a defoliant for Pima when temperatures are cool.
    • Defoliation Research on Pima Cotton at the Maricopa Agricultural Center in 1990

      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 evaluate the effectiveness of selected defoliant treatments on Pima cotton under warm and cool weather conditions. Dropp was effective as a one application defoliant in September when air temperatures were in the high 90's. In October, when night temperatures were lower, no defoliant tested was effective in a single application.
    • Effect of Plant Growth Regulators Under Short-Season Conditions on Pink Bollworm Populations, Cotton Yields and Defoliation

      Chu, Chang-chi; Henneberry, Thomas J.; Bariola, Louis A.; Deeter, Brian; Silvertooth, Jeff; Bantlin, Marguerite; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ; Rhone Poulenc Ag Co., Wickenburg AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Plant growth regulators (PGR's) [thidiazuron (Dropp®) N-phenyl-N' -1,2,3-thiadiazol -5 ylurea, 50% wettable powder, Nor-Am Agricultural Products, Inc., Naperville, IL, and ethephon (Prep®) a- chloroethyl phosphonic acid Rhone - Poulenc Ag Co., Research Triangle Park NC] were applied to reduce late- season fruiting forms as a source of host material for developing overwintering PBW populations. Combinations of ethephon and thidiazuron or thidiazuron alone were more effective than ethephon alone for reducing late -season immature green bolls. None of the PGR's alone or in combination affected yields. Highest rates of defoliation occurred after applications of thidiazuron. The data suggest that temperature thresholds for highest plant growth regulator activity occur.
    • 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.
    • Effect of Plant-Derived Oils on Sweetpotato Whitefly on Cotton

      Butler, G. D. Jr.; Coudriet, D. L.; Henneberry, T. J.; Silvertooth, Jeff; Bantlin, Marguerite; USDA-ARS-Western Cotton Research Laboratory, Phoenix AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Cottonseed oil applied to cotton repelled sweetpotato whitefly (SPW) adults up to 8 days in greenhouse tests. Soybean oil (5 %) resulted in reduced numbers of adults and numbers of eggs laid. SPW egg hatch was reduced 84% after treatment with 10% crude cottonseed oil solutions as measured by the number of first instar larval emergence. Also, numbers of whitefly larvae were reduced 99, 91 and 83% on day 6 following treatment with 10% cottonseed oil, S and 1.5% soybean oil, respectively. Negligible plant leaf phytotoxicity occurred from the plant-derived oil treatments.
    • Effects of 3 Irrigation Termination Dates on a Full Season Type of Upland Cotton in Mohave Valley, Arizona

      Grumbles, R. L.; Hood, L.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      A single field experiment was conducted in 1990 on a grower cooperator field to evaluate the response of a full season maturity type of Upland Cotton (DPL 90) to three dates of irrigationtermination. The crop was planted 26 and 27 of March, managed uniformly in all respects until August 1 when earliest irrigation termination wsa imposedThe dates for the second and final irrigationtermination treatments were 15August and 15 September. Each irrigationtermination treatments were given an additional 8 acre inches of water (approximate). Harvest results revealed no significant differences in lint yield on the first two dates but the last date yielded 110 pounds more. All plots received a 2 inch rain 18 August.
    • Evaluation of Date of Planting and Irrigation Termination on the Yield of Upland and Pima Cotton

      Silvertooth, J. C.; Watson, T. F.; Terry, L. I.; Malcuit, J. E.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Four flea experiments were conducted in 1990 in Arizona to evaluate the response of Upland and Pima cotton to dates of planting and dates of irrigation termination. Planting dates ranged from as early as 27 February in the Yuma Valley (150 ft. elevation) to 8 May at Marana (2,000 ft. elevation). Dates of irrigation termination ranged from 18 July in the Yuma Valley to 8 September at Maricopa and Marana.
    • Fat Content and Reproductive Condition of Migrating and Dispausing Boll Weevils in South Carolina and Arizona

      Leggett, J. E.; Silvertooth, Jeff; Bantlin, Marguerite; USDA-ARS-Western Cotton Research Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1991)
      Overwintered female boll weevils, Anthonomus grandis Boheman, collected in grandlure- baited traps were significantly leaner than weevils taken from winter habitat. Weevils that emerged from naturally infested cotton bolls tended to be fat as adults regardless of subsequent adult diet, but adult diet can affect gonadal development. Weevils that emerged from bolls in 1975 in South Carolina had a higher winter survival rate and emerged from winter habitat earlier than the total population. Migrant weevils appear to be mainly colonizers that have some body fat and medium size gonads. The physiological condition of migrants was fairly consistent over time and location in South Carolina but not in Arizona. The time of migratory flight was related mainly to plant maturity and population levels in South Carolina. Weevils collected from cotton plants in South Carolina and Arizona had significantly more body fat than weevils trapped at the cotton field but oogenesis was variable between the two locations.