• Susceptibility of Lygus Bug Populations in Arizona to Acephate (Orthene®) and Bifenthrin (Capture®), with Related Contrasts of Other Insecticides

      Dennehy, T. J.; Russell, T. J.; Silvertooth, Jeff; Extension Arthropod Resistance Management Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Adult lygus bugs, Lygus hesperus (Knight), were collected from alfalfa fields in 11 different cotton producing areas of Arizona. A standardized glass vial method was used to estimate susceptibility of the collected populations to the organophosphate insecticide, acephate (Orthene®), and the pyrethroid bifenthrin (Capture®). Overall, lygus from throughout the state were significantly less susceptible to acephate and bifenthrin in 1995, than in 1994. Resistance of lygus to acephate continues to be widespread and intense, but not uniform in Arizona. In 1995, all populations possessed individuals capable of surviving exposure to vial treatments of 10,000 μg/ml acephate. Lygus bugs from Safford and Maricopa represented the most and least susceptible populations, respectively, to both acephate and bifenthrin. These two populations were tested for susceptibility to nine other insecticides: aldiaarb (Temik®), dimethoate (Gowan Dimethoate E267®), endosulfan (Gowan Endosulfan 3EC®), imidacloprid (Admire 2F®), malathion (Gowan Malathion 8®), methamidophos (Monitor 4®®), methomyl (Lannate LV®), oxamyl (Vydate 3.77L®), apt oxydemeton- methyl (Metasystox-R SC®). The Maricopa population was significantly less susceptible to six of these insecticides. Our findings support the hypothesis that the intensive use of pyrethroid and organophosphate insecticides for whitefly control in cotton has selected for resistance in lygus. This result portends increased problems with lygus control in the future, points to the need for developing new tools for controlling lygus bugs in Arizona cotton, and underscores the urgent need to find alternatives to the current heavy reliance on insecticides for managing whiteflies in cotton.
    • Telone II® and Temik® Efficacy on Root-knot Nematodes in Cotton

      Husman, S.; McClure, M.; Deeter, B.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      A field plot in western Maricopa county was established in 1995 to determine the ability of Temik® brand aldicarb pesticide to suppress root-knot nematode when Temik 15G was applied as a seedling side-dress and moved into the root zone by irrigation. Telone II® was used for comparative purposes and Gaucho-treated seed, following a preplant application of Telone, was included to determine if additional benefits could be realized by systemic control of insects during early stages of plant growth. Plans to include foliar applications of Orthene® were abandon when early season thrips populations failed to develop. Temik 15G, applied as a side-dress at 10 lbs. did not suppress nematodes or increase lint yield Telone, alone and in combination with Gaucho -treated seed, reduced nematode populations and increased lint yield, but differences between the two Telone treatments were not significant. Insect pressure was not a contributing factor. Greenhouse studies showed that both timing of the application and its placement in the row will be of critical importance when Temik is applied for nematode control in furrow irrigated cotton.
    • Tillage Energy Savings from Zone Burial of Shredded and Whole Cotton Stalks

      Carter, Lyle; Chesson, Joe; Thacker, Gary; Penner, Vic; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Two prototypes of a stalk burial implement were tested for energy requirements at the University of California, Shaffer Research Station. Both versions of the implement are designed to bury the cotton stalks in a concentrated zone and reform the bed in the same location. To plow under shredded stalks, both versions of the implement required less energy than a conventional tillage systems typical of the San Joaquin Valley of California. Both stalk burial implements were also used to plow under whole cotton stalks. This offers additional energy savings by eliminating the stalk shredding operation.
    • Upland Advance Strains Cotton Variety Test at the Maricopa Agricultural Center, 1995

      Hart, G. L.; Nelson, J. M.; Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Eighteen upland cotton advance strains were grown in a replicated trial at the Maricopa Agricultural Center. Lint yield, boll size, lint percent, plant population, plant height and fiber property are presented in this report.
    • Upland Cotton Water Stress Sensitivity By Maturity Class

      Husman, S.; Metzler, F.; Wegener, R.; Johnson, K.; Schnakenberg, L.; Brown, P.; Martin, E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Lint yield response to three irrigation treatments based on allowable soil moisture depletion regimes of 50, 75, and 100% depletion of available soil moisture was tested on both a determinate (D&PL 5415) and an indeterminate (D&PL 5816) upland cotton. Arizona Meteorological Weather Networks' (AZMET) potential evapotranspiration (ETo) estimates in combination with cotton crop coefficients were used in a summation manner until targeted depletion thresholds were reached which then triggered the desired irrigation event. The experiment consisted of three irrigation treatments with each main irrigation treatment containing both the determinate and indeterminate variety selection resulting in a randomized complete block split plot design. Actual irrigation volume delivered was 46, 42, and 32 acre inches /acre in 1994 and 52, 48, and 36 acre inches /acre in 1995 for the wet, medium, and dry treatment respectively. Lint yields were significantly reduced in 1994 when available soil moisture depletion exceeded 75% in the determinate variety with no significant yield differences in the indeterminate variety in 1994 across all irrigation treatment regimes. In 1995, lint yields were down across all treatments and varieties with the only statistically significant reduction in lint yield (relative to all 1995 yields) occurring in the dry indeterminate block
    • Upland Regional Cotton Variety Test at the Maricopa Agricultural Center, 1995

      Hart, G.; Nelson, J. M.; Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Twenty-seven upland cotton varieties were grown in a replicated test at the Maricopa Agricultural Center as part of the National Cotton Variety Testing Program. Lint yield, boll size, lint percent, plant population, plant height and fiber property data are presented in this report.
    • Weed Control in Roundup Ready® Cotton: Preliminary Experiments

      McCloskey, William B.; Dixon, Gary L.; Moffett, Jody E.; Silvertooth, Jeff; Department of Plant Sciences, University of Arizona, Tucson, Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      The efficacy of Roundupm herbicide for the control of common Arizona weeds in Roundup Ready® cotton was evaluated in field studies conducted at the Maricopa Agricultural Center in 1995. Promising results were obtained with 1 lb a.i./A (1 quart/A) over-the-top band applications of Roundup when cotton had 1 to 2 true leaves followed by a second, "sloppy", post-directed application ofRoundup at 1 lb a.i./A when cotton had 4 to 5 true leaves. Excellent control of small Palmer Amaranth, Wright Groundcherry, and annual morningglory seedlings was obtained with each 1 lb a.i./A Roundup application in the broadleaf weed study. The two sequential 1 lb a.i./A Roundup applications kept plots free of broadleaf weeds until layby. In the nutsedge weed control study, it was found that nutsedge plants treated with a single 1 lb a. i./A application of Roundup were stunted and exhibited leaf chlorosis, but efficacy was marginal with weed control ratings of only 40 to 50 percent. Nutsedge control ratings for an application of norflurazon (i.e., Zorial) alone or combined with Roundup applied at the 1 to 2 true leaf stage of cotton were 63 and 75 percent, respectively. Two sequential applications of Roundup at 1 lb a.i./A, both with or without norflurazon, resulted in about 90 percent nutsedge control. Roundup Ready cotton exhibited good tolerance to two sequential early season 1 lb a.i./A Roundup applications, as made in these studies, with no apparent seed cotton or lint yield reductions.