• Effects of Entomopathogentic Nematodes on Pink Bollworm Mortality

      Henneberry, T. J.; Forlow Jech, L.; Burke, R. A.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Steinernema riobravis Cabanillas, Poinar & Raulston infected pink bollworm Pectinophora gossypiella (Saunders), larvae over a temperature range of 15.6 - 38.0° C. Temperatures of 32.2° C and higher and exposure for 48 h or more often resulted in decreased numbers of nematode killed larvae with living nematodes and increased numbers of dead larvae with dead or no nematodes.
    • Defoliation of Pima and Upland Cotton at the Safford Agricultural Center, 1997

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Nine defoliation treatments were applied to Pima and upland cotton to compare the treatment effects on percent leaf drop and percent green leaves left and any effects they might have on yield or fiber qualities. All of the treatments were beneficial compared to the untreated check, the treatments including Ginstar performed better than those without.
    • Late Season Pink Bollworm Pressure in the Top Crop of Bt and Non-Bt Cotton

      Knowles, Tim C.; Dennehy, Tim J.; Rovey, Albert; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Green bolls (100/field) were sampled from the uppermost internodes within adjacent fields of Bt (Deltapine 33B) and non-Bt (Hyperformer HS 44) cotton experiencing severe pink bollworm pressure late in the growing season. Average top crop lint yield reductions ranging from 30 to 70% were observed in the uppermost bolls of the non-Bt cotton variety. Average top crop lint yield reductions ranging from 0 to 40% were observed in the uppermost bolls of the transgenic Bt cotton variety.
    • Whitefly Management in Arizona: Conservation of Natural Enemies Relative to Insecticide Regime

      Naranjo, Steven E.; Hagler, James R.; Ellsworth, Peter C.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ; University of Arizona, Maricopa, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Field studies were conducted in 1997 to evaluate strategies for management of whitefly (Bemisia tabaci). We evaluated the effects of different insecticide regimes (conventional and insect growth regulators [IGR]) on the abundance of native parasitoids and predators associated with whitefly in Arizona cotton. Immature parasitoids were most abundant in untreated control plots and there was little difference among insecticide regimes. Percentage parasitism was low overall (< 30 %), but was highest in Knack plots and lowest in untreated control and Applaud plots. Predator populations were lowest in plots treated with conventional insecticides, and there were several instances where weekly or season -long populations of several predator species/groups were slightly depressed in IGR plots compared with the untreated check. Overall, results are encouraging and indicate that use of IGRs helps to conserve populations of native natural enemies.
    • Evaluation of a Nitrogen-15 Microplot Design in a Furrow Irrigated Row Crop System

      Silvertooth, J. C.; Navarro, J. C.; Norton, E. R.; Sanchez, C. A.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Two field experiments were conducted in Arizona in at two locations, Maricopa in 1991 (Casa Grande sandy loam) and Marana (Pima clay loam) in 1995. The purposes of the experiments were to evaluate the dimensions of an ¹⁵N microplot design used in a furrow irrigated row crop system. The experiments each utilized ammonium sulfate fertilizer with 5 atom % ¹⁵N enrichment applied at a rate of 56 kg N/ha in simulated side-dress band application during the early bloom stage of development of Upland cotton (Gossvpium barbadense L). At each location, microplots were 4, 1.02 m rows wide and 1.00 m in length. Whole plant samples were collected at specific locations within and near the microplots. Uptake of ¹⁵N by plants was uniform within microplots but declined symmetrically in relation to microplot borders. Collection of plant materials within 25 cm of microplot borders provided uniform ¹⁵N enrichment levels for determining fertilizer N uptake and recovery. Use of microplots with the dimensions of those used in this study are sufficient for collecting plant materials from a 1 m² area; consisting of two, 50 cm segments from the interior two rows of the four row microplot. This also allows for sufficient distance from the perimeter of the microplot to account for border effects.
    • Whitefly Management in Arizona: Contribution of Natural Enemies to Whitefly Mortality

      Naranjo, Steven E.; Ellsworth, Peter C.; Diehl, Jonathon W.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ; University of Arizona, Maricopa, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Direct-observation studies were conducted to identify causes and estimate rates of mortality of whiteflies over the course of four generations between late June to early September in replicated experimental plots. In plots receiving no whitefly insecticides. predation and dislodgment were major sources of egg and nymphal mortality and overall survival from egg to adult ranged from 1-8.5%. Similar patterns were observed in plots treated with insect growth regulators. except that Knack caused high levels of egg inviability and Applaud was a major source of mortality in small nymphs during the second generation immediately following single applications of these materials. Mortality due to predation was generally lowest for eggs and nymphs in plots treated with a rotation of conventional insecticides reflecting disruption of the predator fauna. Parasitism was a very minor source of mortality throughout. The selective action of the IGRs enhances the abundance and activity of natural enemies resulting in high levels of whitefly control with minimal use of disruptive insecticides. Natural enemies likely contribute to the "extended" residual effects of IGRs so commonly reported by growers.
    • The 1998 Cotton Advisory Program

      Brown, P.; Russell, B.; Silvertooth, J.; Ellsworth, P.; Husman, S.; Knowles, T.; Clark, L.; Dunn, D.; Schneider, M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Arizona Cooperative Extension generates and distributes weather -based Planting Date and Cotton Development Advisories for 19 cotton production areas (Aguila, Buckeye, Cochise Co., Coolidge, Eloy, Greenlee, Co., Harquahala, Laveen, Litchfield Pk., Marana, Maricopa, Mohave Valley, Paloma, Parker, Pinal Co., Queen Creek, Roll, Safford and Yuma Valley). Planting Date Advisories are distributed from legal first planting date until the end of April and provide updates on heat-unit-based planting windows, recent and forecasted weather conditions, heat unit accumulations, variety selection, soil temperatures, recommended plant population, and early insect management and control. Cotton Development Advisories are distributed from early May through the end of August and provide updates on crop development, insects, weather and agronomy. The Cotton Advisory Program will continue in 1998, and growers may obtain advisories by mail/fax from local extension offices or by computer from the AZMET Internet Web Page (http://ag.arizona.edu/azmet) and AZMET Computer Bulletin Board System. Program changes planned for 1998 include 1) an expanded weather information update and 2) the addition of an advisory for the Buckeye area.
    • Marana Pima Test, 1997

      Hart, G. L.; Nelson, J. M.; Barney, Glen; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Nine pima cotton varieties were grown at Marana Agricultural Center as part of the national cotton variety testing program. Lint yield, boll size, lint percent, and plant population are presented in this report.
    • Cotton Defoliation Evaluations, 1997

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Three field experiments were conducted near Yuma, Coolidge, and Marana, AZ in 1997 to evaluate the effectiveness of a number of defoliation treatments on Upland (var. DP NuCotn 33b) cotton. All treatments consisted of materials commercially available in Arizona. Results reinforce general recommendations regarding the use of low rates (relative to the label ranges) under warm weather conditions and increasing rates as temperatures cool.
    • Nitrogen Management Experiments for Upland and Pima Cotton, 1997

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Two field experiments were conducted in Arizona in 1997 at two locations (Maricopa and Marana). The Maricopa experiment has been conducted for eight consecutive seasons, the Marana site was initiated in 1994. The purposes of the experiments were to validate and refine nitrogen (N) fertilization recommendations for both Upland and Pima cotton. The experiments each utilized N management tools such as pre- season soil tests for NO₃⁻-N in- season plant tissue testing (petioles) for N fertility status, and crop monitoring to ascertain crop fruiting patterns and crop N needs. At each location, treatments varied from a conservative to a more aggressive approach of N management. Results at each location revealed a strong relationship between the crop fruit retention levels and N needs for the crop. This pattern was further reflected in final yield analysis as a response to the N fertilization regimes used. The higher, more aggressive, N application regimes did not benefit yields at any location.
    • IPM/BMP Practices in Arizona Cotton

      Baker, Paul B.; McCloskey, William B.; Sherman, Will; Dennehy, Timothy D.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Arizona cotton growers were surveyed regarding the importance of Integrated Pest Management (IPM) and Best Management Practices (BMP). Telephone surveys reached 249 individuals over a ten-day period. The survey asked growers to rate the importance of each IPM/BMP tactic on a scale of 1 (not important) to 5 (very important). Of the 14 practices /tactics listed for IPM, eight had significant chi-square values. These included scouting, crop rotation, variety selection, petiole testing for nitrogen, pheromone use, equipment calibration, and stalk destruction. Of the eight practices /tactics listed for BMP, six had significant chi -square values. These included crop rotation, timing and splitting of nitrogen applications, petiole testing, time of planting and variety selection for specific suppression (Bt cotton). In general, whether it was an IPM, weed management, or a BMP practice/tactic, the growers scored a majority of the tactics as important. It could be inferred from the growers' responses that they agree that the practices listed as important were, in fact, important grower practices.
    • Evaluation of Irrigation Termination Affects on Upland Cotton, 1997

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      A single field study was conducted in 1997 at the Maricopa Agricultural Center (1,175ft. elevation) to evaluate the effects of three dates of irrigation termination on the yield of a common Upland cotton variety (DP NuCOTN 33b). Planting date was 9 April (668 HU /Jan 1 86/55° F thresholds. Three dates of irrigation termination (IT1, IT2, and IT3) were imposed based upon crop development into cut -out. The earliest irrigation termination date, IT1 (7 August) was made as early as possible in an attempt to provide sufficient soil - water such that bolls set at the end of the first fruiting cycle would not be water stressed and could be fully matured. The second termination (IT2) date was 20 August, and provided one additional irrigation over IT1. The final (IT3) date was 17 September, which was staged so that soil moisture would be sufficient for development of bolls set up through the last week of September and provide full top-crop potential. Lint yield results revealed no differences among any of the IT treatments. Mirconaire values increased slightly with later IT dates.
    • Irrigation Efficiencies and Lint Yields of Upland Cotton Growth at the Maricopa Agricultural Center, 1997

      Sheedy, Mike; Watson, Jack; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      A field trial was conducted at the Maricopa Agricultural Center to observe the effects of four irrigation efficiencies (65%, 75%, 85%, and 95%) on the lint yield produced from two upland cotton varieties (DP 5409 and SG 125). Nitrogen requirements for the crop were determined using pre- season soil samples and in season petiole samples in conjunction with crop monitoring data collected at weekly intervals. AZSCHED was used as a guide to the irrigation timing and amount of water applied during the season. This year there was a lint yield response to the different irrigation efficiencies, and a slight difference in yield between the two varieties. Lint yields were significantly lower in the 95% irrigation efficiency plots. Lint Yields ranged from 1448 # lint /acre (SG125 at 75%) to 1220 # lint/acre ( DP5409 at the 65% irrigation efficiency).
    • Evaluation of Planting Date Effects on Crop Growth and Yield for Upland and Pima Cotton, 1997

      Silvertooth, J. C.; Norton, E. R.; Brown, P. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Three field studies were conducted in 1997 at the Maricopa (1,175 ft. elevation) and Marana (1,974 ft. elevation Agricultural Centers to evaluate the effects of three planting dates on yield and crop development for three representative Upland varieties. Planting dates ranged from 13 March to 8 May and also 312-1159 HU/Jan 1 (86/55° F thresholds). Crop monitoring revealed increased vegetative growth tendencies with later plantings. General trends also showed decreasing lint yield with the later plantings for all varieties at each location.
    • Short Staple Regional Cotton Variety Trials, Graham County, 1997

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Two on farm, replicated short staple variety demonstrations were planted in 1997. Twelve varieties were evaluated on the Carpenter farm in Central and on the Colvin farm in Eden. Several new varieties were planted in both studies, including 2 transgenic varieties, DP 35B and BXN 47, 2 varieties from Australia and four other varieties seen for the first time. DP 35B and Stoneville 474 were the highest yielding varieties in Central and the Australian variety, IF 1003, had the highest yield in Eden with yields over 2 bales per acre. Other agronomic data from the varieties and 11111 values from the lint are also included in this report.
    • Evaluation of B. T. Cotton Deployment Strategies and Efficacy against Pink Bollworm in Arizona

      Simmons, A. L.; Dennehy, T. J.; Tabashnik, B. E.; Antilla, L.; Bartlett, A.; Gouge, D.; Staten, R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      A multi- agency team in Arizona in 1997 evaluated B.t. cotton deployment strategies in a large field trial; conducted statewide monitoring of pink bollworm (PBW) susceptibility to the Cry1Ac endotoxin, and established a Rapid Response Team that investigated claims of unacceptable performance of B.t. cotton. Though needing further evaluation, in-field refuges of one row of non-B.t. cotton for each five rows of B.t. cotton showed promise as an alternative to the current recommendation of external refuges for planting B.t. cotton. Preliminary results of statewide monitoring showed that four field populations were more susceptible to Cry1Ac than were two reference susceptible laboratory strains. A strain of PBW previously reported to be resistant to CrylAc was confirmed to be significantly less susceptible to this toxin than were the two susceptible laboratory strains or the four field populations tested. The Rapid Response Team, based at the Arizona Cotton Growers Association, investigated nine reports of unusual larval survivorship in B.t. cotton. Only one of these, which has been placed in culture, was confirmed to have resulted in substantial numbers of large larvae surviving in bolls of putatively B.t. cotton. Further investigations of this population and the plants from which it was derived are underway.
    • Arizona Upland Cotton Variety Testing Program, 1997

      Silvertooth, J.; Norton, R.; Clark, L.; Husman, S.; Knowles, T.; Gibson, R.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Eleven field experiments were conducted in major cotton growing areas of Arizona in 1997 for the purpose of evaluating Upland cotton varieties in terms of adaptability and performance. Six commercial cottonseed companies participated in the program. A maximum of two varieties were submitted by each company at each location. Experiments were conducted on a commercial level on grower-cooperator fields in most cases. Locations used in the program spanned the range of conditions common to cotton producing areas of the state from about 100 ft. to 4,000 ft. elevation. Results indicated a broad range of adaptability and competitiveness. Each of the participating seed companies offer a compliment of varieties that can serve to match various production strategies commonly employed in the state. Many varieties commercially available performed well at several locations demonstrating good adaptation to Arizona conditions.
    • Marana Upland Test

      Hart, G. L.; Nelson, J. M.; Barney, Glen; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Twenty four upland cotton varieties were grown at the Marana Agricultural Center. Lint yield, boll size, lint percent, plant population and fiber property data are presented in this report.
    • Silverleaf Whitefly Cotton Cultivator Preference

      Chu, C. C.; Natwick, E. T.; Henneberry, T. J.; Cohen, A. C.; Castle, S. J.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      All of nine cotton cultivars tested were susceptible to silverleaf whitey, Bemisia argentifolii Bellows and Perring in Imperial valley, CA in 1995 and 1996. Using 4.1 adults per leaf turn as an insecticide- treatment action threshold, Deltapine (DPL) 5409 and 5415 required 5.5 applications of insecticide, DPL 50, 5461, and 5517 required 6 applications, DPL 5432 and 5690 required 65 applications, Louisiana (LA) 887 required 7 application, and Stoneville (ST) 474 required 7.5 applications. Results indicate the potential to reduce insecticide application by selecting appropriate cultivars that are commercially available.
    • Short Staple Variety Trials in Cochise County, 1997

      Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Variety trials were grown at two locations and with two different sets of short staple varieties. One trial on the Robbs farm, north of Kansas Settlement, tested one acala variety from New Mexico two varieties from Australia and SureGrow 125, the highest yielding variety in Curry trial in 1996. The other trial on the Ed Curry farm, near Sunsites, tested twelve upland varieties as part of the statewide testing program. The highest yielding variety in the Robbs trial was SG 125 with a yield approaching 1.7 bales per acre. In the Curry trial, SureGrow 404, the highest yielding variety in the 1995 trial, had the highest yield approaching 2.5 bales per acre.