• 1993 Parker Valley & Mohave Valley Short Staple Cotton Variety Trial

      Hood, L. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Two short staple cotton variety trials were conducted in the Colorado River Basin. One trial was located in the Parker Valley and one in the Mohave Valley. Ten varieties from various seed companies were entered in each test. Yields varied considerably among varieties and locations. However, these trials among others provides evidence that current variety choices are viable components of Arizona cotton production.
    • 1994 Cottonseed Treatment Evaluations

      Norton, E. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Cottonseed was treated with several fungicide treatments in an effort to protect the seed and seedling from disease. Seed germination and vigor was evaluated in three Arizona locations; Maricopa, Marana, and Safford. Stand counts were taken on two separate dates after emergence at both Safford and Marana and once at Maricopa and percent emergence was calculated. Among the three locations two, Marana and Safford, showed significant differences among treatments. Treatment number 5 placed first at both locations where significant differences were found. The untreated control placed last in the ranking at both Marana and Safford for all dates of sampling.
    • 1994 Low Desert Upland Cotton Advanced Strains Testing Program

      Husman, S. H.; Jech, L. E.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Forty eight , non -commercially available advanced strains cotton varieties were tested in 1994 on a commercial farm in Gila Bend, AZ. D &PL 5415 and Sure Grow 501 were included as commercial checks for comparison purposes. Ten participating cotton seed breeding companies entered five lines each of materials which were felt to show promise for potential commercialization. Lines were specifically chosen for their potential for yield performance under low desert environmental conditions. Each plot was six rows wide by 38 feet long replicated four times. The test was planted on April 1, 1994 and harvested on November 17 and November 29, 1994 for both the first and second pick respectively.
    • 1994 Weather Conditions

      Brown, P.; Russell, B.; Silvertooth, J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      The 1994 cotton production season began with near optimal weather conditions. Temperatures and precipitation during planting and early vegetative growth were near optimal levels and were generally near normal. Summer brought an extended period of high day and night temperatures which began in June and continued through September at most locations. The period of high temperature associated with the monsoon (July and August) coincided with a rapid decline in fruit retention across much of the state. While the monsoon provided the usual rise in night temperature and humidity, summer rainfall was relatively light at most locations. Early fall weather was warm and dry, providing generally good conditions for finishing the crop. Weather conditions then cooled dramatically in the late fall prior to the onset of heavy rains in December. The wet December conditions limited post harvest field work in many locations.
    • The 1995 Arizona Cotton Advisory Program

      Brown, P.; Russell, B.; Silvertooth, J.; Ellsworth, P.; Stedman, S.; Thacker, G.; Husman, S.; Cluff, R.; Howell, D.; Winans, S.; Grumbles, R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Arizona Cooperative Extension generates and distributes weather -based Planting Date and Cotton Development Advisories for 11 cotton production areas (Marana, Laveen, Paloma, Litchfield Pk., Pinal Co., Parker, Mohave Valley, Queen Creek, Safford, Yuma Valley, and Aguila). Planting Date Advisories are distributed from mid- February through the end of April and stress 1) planting cotton varieties according to heat unit accumulations rather than calendar date and 2) the importance of soil temperature to good germination. Cotton Development Advisories are distributed from early May through mid -September and provide updates on crop development, insects, weather and agronomy. The Cotton Advisory Program will continue in 1994 and growers may obtain the advisories by mail or fax from the local county extension office, and by computer from the AZMET computer bulletin board. Improved normal weather statistics and the addition of an advisory for Cochise County are the main changes planned for the 1995 program.
    • Arizona Upland Cotton Variety Testing Program

      Silvertooth, J.; Norton, R.; Clark, L.; Husman, S.; Cluff, R.; Stedman, S.; Thacker, G.; Grumbles, R.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Ten field experiments were conducted in many of the cotton growing areas of Arizona in 1994 for the purpose of evaluating Upland cotton varieties in terms of adaptability and performance. Seven commercial cottonseed companies participated in the program. Two varieties were submitted from each company at each location. Experiments were conducted on grower- cooperator fields in each case. Locations used in the program spanned the range of conditions common to cotton producing areas of the state from about 500 ft. to 4,000 ft. elevation. Results indicated a broad range of adaptability and competitiveness on the part of each of the participating companies and their representative varieties. Each of the companies offers a compliment of varieties that can serve to match various production strategies commonly employed in the state as well as showing a strong capacity to be regionally adaptive.
    • Bioassay Results in Field Persistence of Two Pink Bollworm Parasitic Nematodes

      Lindegren, J. E.; Henneberry, T. J.; Forlow Jech, L. J.; Burke, R. A.; Silvertooth, Jeff; USDA-ARS, HCRL, Fresno, CA; USDA-ARS, WCRL, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Steinernema carpocapsae (Weiser) and S. riobravis Cabanillas, Poinar and Raulston applied in the field at the rate of 1 billion nematodes /acre equivalent persisted in the soil for 63 and 6 days, respectively. Persistence of S. riobravis in the field may offer the potential for introduction and permanent establishment of this nematode for pink bollworm (PBW), Pectinophora gossvpiella (Saunders), control in southwestern cotton growing areas.
    • Chemical Control of the Sweetpotato Whitefly in Cotton

      Watson, T. F.; Tellez, M. A.; Peña, M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Various registered and experimental insecticides were evaluated for sweetpotato whitefly (Bemisia tabaci Gennadius) control in several field experiments at Yuma, Arizona in 1994. Best controls were obtained with insecticide mixtures, particularly a pyrethroid and an organophosphate, rather than with individual materials. Results of these experiments indicate that severe population densities can be controlled using insecticide combinations, even though sustained use of these insecticides would probably lead quickly to the development of resistance.
    • Community-wide Implementation of Samplin and Action Thresholds for Whiteflies in Cotton

      Diehl, J. W.; Ellsworth, P. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Sampling and decision-making plans for managing sweetpotato whiteflies were implemented within 8,000 acres of cotton within the Laveen-Tolleson area of central Arizona. On the average, thresholds utilized for the first whitefly treatment were lower than those recommended, but subsequent treatments were made at about recommended thresholds.
    • Comparative Analysis of Two Sampling Methods for Estimating Abundance of Adult Bemisia tabaci in Cotton

      Naranjo, S. E.; Flint, H. M.; Henneberry, T. J.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      The leaf turn method and the black pan method, two sampling methods for estimating the abundance of Bemisia tabaci (Strain B) on cotton, were compared over a two year period in Maricopa and Phoenix, AZ Both methods were highly correlated with the density of immature stages prior to the use of insecticides, but more poorly correlated after insecticide use began. The two methods were highly correlated with one another, however, leaf turn counts were better predictors of immature infestation. The leaf turn method was also much less variable between individual samplers than the black pan method. Finally, in terms of cost-efficiency it takes, on average, 71% less time to estimate population density with an acceptable precision using the leaf turn method. Based on these criteria, the leaf turn method is a more reliable and efficient technique for estimating adult abundance.
    • Comparison of Irrigation Scheduling Methods in Cotton Production

      Martin, E. C.; Pegelow, E. J.; Stedman, S.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Three different irrigation scheduling techniques were compared in this study; aerial infrared, hand -held infrared, and neutron moisture gage measurements. There were four treatments with three replications of each. Treatment one was scheduled using aerial infrared imaging and analyzes performed by Agrometrics, Inc. Treatment two was scheduled using a hand -held infrared gun. Irrigations for this treatment were initiated at a crop water stress index value of 0.3. Treatments three and four were scheduled using neutron probe measurements. Treatment three was irrigated at 45% depletion of the available soil water. Treatment four was irrigated at 45% depletion of the available soil water until mid-bloom, when the strategy was changed to irrigate at 35% depletion. Yield results showed no significant difference between the treatments.
    • Cotton Defoliation Evaluations, 1993

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Two field experiments were carried out in representative cotton producing areas of Arizona to evaluate the effectiveness of a number of defoliation treatments on Pima cotton. These experiments were conducted at Coolidge and Marana. The treatments employed principally consisted of relatively new materials available in Arizona, and were compared to current standard treatments. All treatments showed promise in terms of effectiveness and the results provide a basis for use recommendations in 1995.
    • Cotton Leaf Curl Virus, A Threat to Arizona Cotton?

      Nadeem, Athar; Xiong, Zhongguo; Nelson, Merritt; Silvertooth, Jeff; Department of Plant Pathology, University of Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A serious virus disease of cotton in Pakistan is distantly related to cotton leaf crumple in Arizona. It is much more destructive on cotton than leaf crumple, and has never been found in the western hemisphere. Cotton leaf crumple in Arizona causes only modestly damaging midseason infections, while leaf curl, has had a major impact on the crop in Pakistan. Modern transportation and the increasing movement of living plants in global trade has resulted in them recent introduction of a similar disease of another crop to the western hemisphere.
    • Crop Water Use Estimates

      Watson, J.; Sheedy, M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Irrigation scheduling, by keeping track of irrigation applications, soil storage and crop water use, has been computerized by a number of different individuals. A key component of the computerized methods is the estimation of a reference crop evapotranspiration rate. Complaints about one such method, AZSCHED, led the authors to compare the reference crop evapotranspiration values calculated by AZSCHED with those calculated by a second procedure available used by AZMET. Results of the comparison indicated that no significant difference existed between methods, for either a traditionally "long season", or a contemporary "short season" growing period. AZSCHED did estimate crop water use to be about 5% - 8% more than AZMET, an amount that is not of importance considering the irrigation inefficiencies created by field non-uniformities. Experience by the authors indicates that inappropriate selection of irrigation efficiencies and/or soil water holding capacity may be the main cause of user complaints.
    • Defoliation of Pima and Upland Cotton at the Safford Agricultural Center, 1994

      Clark, L. J.; Carpenter, E. W.; Odom, P. N.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Experiments were effected on both Pima and upland cotton to compare the defoliation effects of different rates of Ginstar, Ginstar + Prep and sodium chlorate with an untreated check. Weather conditions after treatment applications were recorded and observations taken after one week and two weeks. Grab samples were taken from the picker to determine percent trash and to run HVI analyses.
    • Defoliation Research on Upland and Pima Cotton at the Maricopa Agricultural Center in 1994

      Nelson, J. M.; Hart, G. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Field studies were conducted at the Maricopa Agricultural Center to evaluate the effectiveness of selected defoliation treatments on Pima and upland cotton under warm and cool weather conditions. Air temperatures were high for tests conducted on 16 and 22 September and cool for tests conducted on 14 October. In September tests, Pima cotton was more susceptible to leaf desiccation after applications of defoliants than upland cotton. Single applications of Ginstar or Dropp + Def gave good defoliation in September tests. In October, Pima cotton was effectively defoliated by chemical treatments but a single application of defoliants did not provide acceptable defoliation of upland cotton.
    • Determining Soil Moisture for Irrigation Management

      Martin, E. C.; Husman, S.; Wegener, R.; Brown, P.; Johnson, K.; Schnakenberg, L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      One key component in good irrigation management is the measurement of soil moisture to help determine when to irrigate. In this study, resistance blocks and tensiometers were compared to neutron probe readings to assess how well these devices followed soil moisture and whether the resistance blocks and /or tensiometers could be used to schedule irrigation in cotton production. The resistance blocks were placed at 6, 18, and 30 inches. Tensiometers were placed at 18 and 30 inches. The readings from the resistance blocks and tensiometers were compared to neutron probe readings taken at 6, 18, and 30 inches. The resistance blocks compared well with the neutron probe readings at the 6 inch and 30 inch depth. At the 18 inch depth, there was much scatter in the data. The tensiometers also showed good comparisons at 30 inches and poor comparisons at 18 inches.
    • Development of a Yield Projection Technique for Upland and Pima Cotton

      Norton, E. R.; Silvertooth, J. C.; Unruh, B. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A series of boll measurements were taken at two locations in 1994 on 5 different varieties in an attempt to develop a yield prediction model. Measurements were taken in strip plot variety trials at Maricopa Agricultural Center and Marana Agricultural Center over a period of approximately 2 months from peak bloom through cut-out. Measurements taken included boll weight, boll diameter, bolls/meter, plants/meter, and final yield from each specific measurement area. Stepwise linear regression resulted in a yield prediction model expressing yield as a function of heat units accumulated after planting, boll diameter or boll weight, and bolls/meter.
    • Does a Preharvest Application of Roundup® Improve Cotton Defoliation?

      McCloskey, William B.; Husman, Stephen H.; Silvertooth, Jeff; Department of Plant Sciences, University of Arizona, Tucson, Arizona; Cooperative Extension, Maricopa County, Phoenix, Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Preharvest applications of Roundup improved defoliation and regrowth suppression when used in conjunction with an application of Dropp +Def on Upland cotton in experiments conducted in Buckeye, Maricopa, and Queen Creek, AZ. However, all treatments used provided commercially acceptable defoliation. Preharvest Roundup applications made about two weeks (or one irrigation interval) before the application of Dropp +Def did not reduce seed cotton yields, lint yields, or affect color-grade and fiber characteristics.
    • Effect of Combinations of Accelerate and other Defoliants on Defoliation and Yield of Pima and Upland Cotton

      Nelson, J. M.; Hart, G. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Field studies were conducted at the Maricopa Agricultural center to evaluate the effectiveness of Accelerate when used in combination with other defoliants. In addition, an experimental compound was tested as a boll opener. Air temperatures were very high at the time these tests were conducted and most defoliant treatments caused desiccation of Pima leaves 7 days after treatments were applied. Several treatments did result in acceptable defoliation of Pima cotton 14 days after application. In the upland test, Ginstar used alone resulted in higher defoliation percentages than any combination of defoliants. Boll opener treatments had no effect on boll opening of Pima or upland cotton. In these tests, there were no differences among treatments in lint yield or fiber properties.