• Survey of Cotton Weeds and Weed Control Practice in Arizona Upland Cotton Fields

      McCloskey, William B.; Baker, Paul B.; Sherman, Will; Silvertooth, Jeff; Department of Plant Sciences, University of Arizona, Tucson, AZ; Department of Entomology, University of Arizona, Tucson, AZ; National Agricultural Statistics Service, USDA, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      The distribution of weed species and the herbicides and cultural practices used to control weeds in Arizona cotton fields were surveyed in 1995 and 1996. The most common weeds were purple nutsedge, bermudagrass, annual morningglory, Palmer amarnath, Wright groundcherry, common purselane, yellow nutsedge and Johnsongrass. The average statewide cost for hand weeding in 1995 was reported as $27.87 per acre in addition to other weed control costs. Statewide, most growers used preemergence herbicides before or at planting and used pre- and post-emergence herbicides later in the season. Most of these applications were broadcast applications suggesting that many of the postemergence herbicide applications were layby applications. Preemergence herbicides (usually applied preplant incorporated) such as Treflan, Prowl, and Prometryn were more commonly used than postemergence herbicides. Statewide, few growers banded preemergence herbicides or used electro- hydraulic quick-hitch guidance systems and in-row weeding tools with their cultivators.
    • 1997 Cottonseed Variety and Treatment Evaluation

      Knowles, Tim C.; Wakimoto, Del, 1947-; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Three upland cotton varieties (Deltapine 5415, Stoneville 474, and SureGrow 125) were subjected to three seed treatments (non or control, standard commercial triple treated, and standard commercial plus Prevail added to the hopper box at 1 lb product /100 lb cottonseed) to determine seed germination and vigor in a Mohave Valley field prone to Rhizoctonia infection of cotton seedlings.
    • 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.
    • Pima Cotton Regional Variety Trial, Safford Agricultural Center, 1997

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Sixteen long staple varieties were tested in a replicated small plot trial on the Safford Agricultural Center in Graham county at an elevation of 2950 feet. The highest yielding variety in 1997 was OA 325 with a yield of 746 pounds of lint per acre. It was followed by four other Olvey varieties yielding over 700 pounds per acre. 1997 was not a good Pima cotton year in this valley, weather problems early and insect problems late in the season both took their toll. Yields were more than 300 pounds lower than the previous year and 100 pounds less than in 1995. Yield and other agronomic data as well as fiber quality data are contained in this paper.
    • Non-chemical Control of Cotton Seedling Damping-off in the Field

      Misaghi, I. J.; Heydari, A.; Zoki, K.; Silvertooth, Jeff; Department of Plant Pathology, University of Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      We conducted four field trials in April 1995 and 1996 in Arizona to compare the effectiveness of the following treatments to reduce cotton seedling damping-off incidence: 1) a soil drench of an isolate of the bacterium, Burkholderia cepacia (DI), recovered by us from cotton plants; 2) isolate D1 barley meal formulation; 3) Deny® seed treatment (a peat moss -based formulation of another isolate of B. cepacia, CCT Corp. Carlsbad, California); 4) Deny® soil drench; 5) Kodiak® seed treatment (a formulation of the bacterium, Bacillus subtilis, Gustafson Inc., Dallas, Texas); 6) a mixture of three fungicides Metalaxyl, Triadimenol, and Thiram seed treatment; and 7) a mixture of Metalaxyl, Triadimenol, Thiram, and Kodiak® seed treatment. Except for DI, the other products are being marketed for the control of cotton seedling damping-off Only DI soil drench and a mixture of the three fungicides seed treatment increased cotton stand significantly (P ≤ 0.05) in three of four field trials.
    • Efficacy of Experimental Insecticides for Whitefly Control in Cotton, 1997

      Kerns, David L.; Tellez, Tony; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Whitefly populations in this trial were abnormally low relative to previous years experiences. M-25 provided excellent whitefly control and was equivalent to the commercial standard (Knack followed by Danitol + Orthene). However, there is some question concerning its adult activity late in the season, when it appeared to be weaker than Danitol + Orthene and Capture + Curacron. At low whitefly populations Thiodan tank -mixed with Knack appeared to extend control over Knack alone.
    • 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.
    • Efficacy of Insecticides for Pink Bollworm and Cotton Leaf Perforator Control in Cotton Grown in the Low Desert Region of Arizona, 1997

      Kerns, David L.; Tellez, Tony; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Neither Tracer nor Proclaim appeared to be effective pink bollworm materials whether applied at day or night. However against cotton leafperforator, both Tracer and Proclaim provided sufficient control. Although all three formulations of Karate equally provided statistically significant pink bollworm control, it was not commercially acceptable. Shortening the spray interval from 7 to 4 days may have helped alleviate this problem. None of the Karate formulations evaluated appeared to offer outstanding cotton leafperforator control.
    • Whitefly Management in Arizona: Looking at Whole Systems

      Ellsworth, P. C.; Naranjo, S. E.; Castle, S. J.; Hagler, J.; Henneberry, T. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Whiteflies remain a threat to production of cotton in Arizona. Looking at a series of commercial-scale trials, levels last season were delayed compared to previous years, but at higher densities than in 1995, an outbreak year. Efforts must be expended to optimize insect growth regulator (IGR) use and integrate these tactics with other aspects of crop and pest management. Broad spectrum insecticide use prior to treatment for whiteflies with IGRs alters the ecology of the system. Whitefly densities consistently increased after disruption with a Lygus insecticide relative to Lygus -untreated areas. While Lygus control is a production imperative, guidelines are presented for minimizing the impact of this disruption. The modes of action for the two IGRs differ substantially and result in subtle changes in population age structure and dynamics. The consequences of these changes impact natural enemies and should be noted by producers when selecting an IGR or monitoring populations after treatment. Re- treatment after initial IGR sprays depends on many factors. While apparently similar levels of suppression are possible when only one IGR is used, regimes using both available IGRs resulted in the fewest number of damaging large nymphs late in the season, just prior to defoliation. Conventional insecticides rotated according to pre-IGR introduction guidelines (`95IRM') also suppressed populations significantly and comparably to IGR regimes until late in the season. Then, whitefly densities rose aggressively just prior to defoliation and pyrethroid susceptibility was significantly reduced in the 951RM regime. Full adoption of IGR -based technology along with `Bt' cotton allows growers to better manage whiteflies with fewer disruptions which can lead to secondary pest outbreaks, pest resurgence, and insecticide resistance.
    • Can Resistance to Chloronicotynl Insecticides be Averted in Arizona Field Crops?

      Williams, Livy III; Denney, Timothy J.; Palumbo, John C.; Silvertooth, Jeff; Department of Entomology, The University of Arizona; Extension Arthropod Resistance Management Laboratory, Tucson, AZ; Yuma Agricultural Center, Yuma, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      A resistance management program was initiated in Arizona in 1995, the initial goal of which was to sustain the efficacy of imidacloprid (Admire®) against Bemisia in vegetable crops. Due to the anticipated registration of additional chloronicotinyl (and related neonicotinyl) insecticides in Arizona, project objectives were subsequently broadened to address management of this entire class of insecticides in Arizona field crops. Results from three years of statewide monitoring of whiteflies from cotton indicated that whitefly populations in Arizona have become significantly less susceptible to imidacloprid in each of the past two years and significant geographical differences were described. However, no evidence was found of reduced field performance of imidacloprid in vegetables. Additionally, laboratory studies subjecting Arizona whiteflies to selection with imidacloprid did not increase levels of resistance beyond those occurring in the field. A study exploring the influence of cropping system differences on imidacloprid use (Admire® and Provado®) revealed no major differences in susceptibility to this insecticide between populations of whiteflies in central and southwestern Arizona. However, distinct seasonal shifts to lower susceptibility from 1996 to 1997 were observed in the Dome Valley of southwestern Arizona. Susceptibility of Arizona whitefly populations to imidacloprid was highly correlated with susceptibility to acetamiprid but was unrelated to susceptibility to CGA-293343. There is an urgent need to harmonize chemical use and resistance management efforts in Arizona cotton, vegetables and melons to avoid conflicts resulting from movement of pests between crops.
    • Correlation between Early Season Insecticide Control of Pink Bollworm and Other Pests and Subsequent Whitefly Applications near Gila Bend, AZ, 1997

      Jech, L. E.; Husman, S. H.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Cotton pesticide application histories in the Gila Basin were followed from 27 April through 20 September. The main interest was the effect of early season applications to control pink bollworm, Pectinophora gossypiella, and other pests on subsequent whitefly applications. Categories explored include, transgenic and non transgenic cotton, planting dates, and location within the valley. Regression analysis shows a significant effect due to the early season control for either P. gossypiella, or other pests (P > 0.009) but lower for them together (P > 0.026). Early applications for either PBW or other pest resulted in increased application for whitefly.
    • 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 Calcium Soil Conditioners in an Irrigated Cotton Production System, 1997

      Griffin, J. R.; Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      A single field experiment was conducted at Paloma Ranch, west of Gila Bend in Maricopa County Arizona in 1996 and 1997. NuCotn™ 33B was dry planted and watered -up on 15 April and 1 April in 1996 and 1997. Various rates and times of application of nitrogen (N) and calcium (Ca) from two sources [N-Cal™ (CO(NH₂)₂•CaC1₂) and CAN-17 (CaNO₃)] as well as a standard N source, UAN-32 [NH₄NO₃•CO(NH₂)₂] were used to evaluate the check In 1996 treatments 1, 2,and 3 each received a total of 280 lbs. N/acre, treatment 4 received a total of 210 lbs. N/acre, while treatment 5 received a total of 301 lbs. N/acre. Treatment 1 received only farm standard applications of UAN-32. Treatments 2 and 4 each received a total of 72 lbs. of Ca/acre. Treatment 5 received a total of 79 lbs. Ca/acre from N-Cal™ while treatment 3 received a total of 301 lbs. Ca/acre from CAN -17. Treatment 4 used a conservative N approach (UA guidelines). 1997 was similar to 1996 in the general nature of the experimental design, but different in its actual treatments. Treatments 2, 3, 4, and 5 each used N-Cal™ for the first two irrigation applications then UAN -32 for continued crop N needs. Treatment 4 used a conservative N approach (U A guidelines). Treatments 3 and 5 each received two foliar applications of N-Cal™ Foliar applications consisted of N-Cal™ mixed with urea for a 15-0-0-8 formula and applied on 22 July and 29 July via a high cycle applicator at a 5 gal/acre rate of N-Cal™ (carrier rate = 40 gal /acre). No significant differences were found among the various treatments in terms of plant growth, soil water content, ECₑ values, and sodium absorption ratios in 1996 or 1997. Lint yields were not significantly different in 1996 (P < 0.05) or 1997 (P < 0.05).
    • Integrated Lygus Management in Arizona

      Ellsworth, Peter C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Integrated Lygus management depends on the same fundamentals of management for any pest. There needs to be a system of monitoring (sampling), understanding of the density-yield relationship (thresholds) and other insecticide optimization practices (e.g., resistance management), and a plan for reducing the chance of infestation and need for remedial measures (avoidance). While all these guidelines are under current study, current recommendations represent a fundamental base on which to build an integrated Lygus management program that will also manage for susceptibility to our current insecticides. Key to this sustainable susceptibility system is limiting insecticide use to the lowest practical levels. This is best accomplished by careful sampling, careful assessment of thresholds and selection of the right compound for the job, but, most of all, avoidance of the problem from the start. Current recommendations are detailed below in light of the most recent research findings.
    • Efficacy of Experimental Insecticides for Insect Control in Cotton Grown in the Low Desert Region of Arizona, 1997

      Kerns, David L.; Tellez, Tony; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Experimental insecticides were evaluated for control of lygus bugs relative to commercial standards in cotton. These products were also evaluated for activity towards whiteflies and pink bollworms. CGA293343 was not effective when used as a side-dress material at layby, but was effective toward whiteflies, and towards lygus at higher foliar rates. Regent, Vydate and Mustang + Thiodan were highly effective for lygus control, while EXP61096A and Mustang alone performed poorly. Against whiteflies, CGA293343, Acetamiprid, and Mustang + Thiodan were most efficacious, while Mustang alone and with Thiodan were most effective towards pink bollworms.
    • Potassium Fertilization of Upland and Pima Cotton (1991-1995, a five year project review)

      Galadima, A.; Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      In an effort to provide information on the agronomic necessity of potassium (K) fertilization in Arizona cotton (Gossypium spp.) production, a five-year study was initiated in 1991 with a single field study located near Gila Bend. Subsequent study sites selected ranged from western (Yuma) to eastern (Safford) Arizona, which totaled 11 site years. Both Upland (G. hirsutum L.) and American Pima (G. barbadense L.) cotton were cultivated, using soil and foliar applications of K. In 1992, study sites included the Safford Ag. Center (SAC), Maricopa Ag. Center (MAC), and a Cooperator site at Coolidge. In 1993, the experiment stations sites were maintained (SAC and MAC) and Yuma Valley was added. The 1994 study sites included only the two experiment stations (SAC and MAC). In 1995, SAC and MAC were maintained, and a third location was a farmer cooperator site at Buckeye. The results from all studies (12) indicated no lint yield increases due to K fertilization at any of the locations with either Upland or Pima cotton. However, in 1995, at the Buckeye location, the result revealed a significant yield reduction due to the K foliar treatments. There were, however, no significant differences among soil as well as the soil-plus-foliar treated plots in the 1995 study at Buckeye.
    • 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.
    • 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.
    • Short Staple Variety Trial, Greenlee County, 1997

      Clark, Lee J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Six short staple cotton varieties including two New Mexico acalas varieties and one advanced strain, two Australian varieties and a SureGrow variety with higher yield potential were tested in this study. The SureGrow variety, SG 125 had the highest lint yield with a yield of 875 pounds of lint per acre, out producing the following varieties by 80 pounds per acre. The average yield was about 100 pounds per acre lower than the previous year, and 50 pounds less than the 5 year average due to a cold spring and an early frost. In addition to lint yields; percent lint, plant heights, height to node ratios, plant populations and lint hvi values are shown. A lint yield comparison for 1993 through 1997 is included in this paper.
    • Infection of Sorghum Varieties by the Cotton Root-knot Nematode, Meloidogyne incognita

      McClure, M.; Husman, S.; Schmitt, M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Twentythree varieties of sorghum, Sorghum bicolor, were evaluated for susceptibility to the cotton root -knot nematode, Meloidogyne incognita race 3. Eggs per gram of root were used as a measure of nematode reproduction and host susceptibility. The nematode reproduced on all varieties tested Mean egg counts were lowest on the varieties Northrup King (NK) KS-737, MF.; NK 1580,M; NK Ks-735 M.F.; NK 714Y MF.; NK Lt. Bronze X 609 M; Ciba-NK C-1506, M; and Pioneer 8877, but these varieties are still considered to be hosts capable of sustaining or increasing nematode populations in cotton fields. All varieties were better hosts than cotton.