• Silverleaf Whitefly and Cotton Lint Stickiness

      Henneberry, T. J.; Forlow Jech, L.; Hendrix, D. L.; Perkins, H. H.; Brushwood, D. E.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ; USDA-ARS, Cotton Quality Research Station, Clemson, SC (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Cotton plant densities of 10 or 40 thousand plants/acre had no effect on numbers of silverleaf whitefly, Bemisia argentifolii Bellows and Perring, adults, eggs, nymphs, extracted sugars from lint samples or thermodetector sticky cotton counts. Higher numbers of whitejlies occurred in early-season in Pima S-7 cotton than in DPL 50 or DPL 5415 cotton. Seasonal averages for sugars, percentages of total reducing sugars and thermodetector counts were higher for DPL 50 compared with Pima S-7 but not DPL 5415. Insecticide treatments reduced thermodetector counts and associated sugars extracted from lint.
    • 1996 Low Desert Upland Cotton Advanced Strains Testing

      Husman, S. H.; Jech, L. E.; Metzler, F.; Wegener, R.; Johnson, K.; Silvertooth, Jeff; Maricopa County Cooperative Extension, University of Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Upland cotton advanced strains and commercial check comparison varieties were evaluated in replicated field studies in 1996 on Cooperator fields in Queen creek, Buckeye, and Gila Bend, AZ. Eight seed companies submitted advanced strains plus a commercially available check of their choice for each site. The highest lint yields for advanced strains entries by location were: J & S Research JSX 12 (1890 lb./acre), Delta Pine and Land Co. DPX 1075 (1420 lb/acre) and Delta Pine and Land Co. DPX 1075 (2510 lb/acre) at Queen Creek, Buckeye and Gila Bend, Arizona respectively.
    • Commercial Field Performance of KNACK™ on Cotton in the Yuma Valley

      Palumbo, John C.; Hannan, Todd A.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      The insect growth regulator, Knack was evaluated for efficacy against sweetpotato whitefly in paired plots within three commercial cotton fields near Somerton, Arizona. A single application of Knack and Danitol/Orthene was made in July and the impact on whitefly populations, natural enemies and secondary pests was measured for 40 d. Knack appeared to act slowly during the first 2 weeks, but after 21 days nymph populations were greatly reduced. Populations of nymphs and adults began to return to their pre-test levels after 40 d. The Danitol/Orthene application resulted in a significant decrease in adult numbers. Initially nymph densities declined, but after 14 d densities appeared to increase at a much greater rate than was observed in the Knack plots. Under the conditions experienced in this study, a single application of Knack in early July provided protection against sweetpotato whitefly as good, or better than experienced with Danitol/Orthene. Reductions in yields or lint quality attributable to whitefly were not observed in either treatment regime. Although beneficial predators were measured throughout the season, insecticide sprays for lygus control prevented significant buildup of populations. However, the numbers of Liriomyza leafminer adults captured on sticky traps were significantly lower in Knack-treated plots.
    • Defoliation of Pima and Upland Cotton at the Safford Agricultural Center, 1996

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Nine defoliation treatments were applied to Pima and upland cotton to compare the treatment effects on percent defoliation of the plants, percent first pick values, percent gin trash and any effects they might have on fiber qualities. All of the treatments were beneficial compared to the untreated check, but differences between treatments were small.
    • Evaluation of Calcium Soil Conditioners in an Irrigated Cotton Production System

      Griffin, J. R.; Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      In 1996 a single field experiment was conducted at Paloma Ranch, west of Gila Bend in Maricopa County Arizona. Nucoton 33B was dry planted and watered -up on 15 April. Treatments consisted of various rates and times of application of nitrogen (N) and calcium (Ca) from two sources (N-Carm and CAN-17), as well as a standard N source, UAN-32, along with a Calcium (Ca) check which received no Ca. Treatments], 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 was a check plot and received only 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 while treatment 4 received a total of 300 lbs. Ca/acre. No significant differences were found among the various treatments in terms of plant growth, soil water content, ECₑ values, and sodium absorption ratios. Lint yields were significantly different (P < 0.07).
    • Management of Pyrethoid-Resistant Whiteflies in Arizona Cotton: Selection, Cross-Resistance, and Dynamics

      Sivasupramaniam, Saku; Dennehy, Timothy J.; Williams, Livy III.; Silvertooth, Jeff; Extension Arthropod Resistance Management Laboratory, The University of Arizona, Department of Entomology, Tucson, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      In 1995, silverleaf whitefly, Bemisia argentifolii Bellows and Perring, resistance to the widely -used mixture of Danitol® (fenpropathrin) + Orthene® (acephate) was shown to be severe and widespread in Central Arizona cotton. Thereafter, laboratory experiments were undertaken to identify the other major insecticides that were affected by this resistance. Whiteflies were collected in November of 1995 from Maricopa (highly resistant) and Yuma (relatively susceptible) County locations in Arizona. A composite colony was established by combining Yuma and Maricopa whiteflies in a 4:1 ratio. After six generations of adult selection of this population with Danitol + Orthene, appreciable shifts in the concentration responses for pyrethroid, organophosphate, and carbamate insecticides were observed, indicating heritable variation for resistance in the source populations. From this we obtained definitive proof that resistance to Danitol + Orthene confers cross-resistance to Asana® (esfenvalerate), Capture® (bifenthrin), Danitol, Decis® (deltamethrin), Decis + Orthene, and Karate® (lambda-cyhalothrin). Additionally, selection with Danitol + Orthene resulted in statistically significant reductions in susceptibility to Curacron® (profenofos), Lannate® (methomyl), Monitor® (methamidaphos), and Ovasyn® (amitraz). Studies were performed to assess tolerance of Maricopa (pyrethroid- resistant) and Yuma (pyrethroid-susceptible) populations to a diversity of conventional insecticides currently registered for use in Arizona cotton, with the intention of finding compounds that showed promise for overcoming pyrethroid resistance. Of the materials evaluated, Curacron, Lannate, Lorsban® (chlorpyrifos), Ovasyn, Supracide® (methidathion), and Vydate® (oxamyl) were most promising. To determine to what degree pyrethroid resistance in cotton influenced resistance in winter vegetables and melons, and vice versa, whitefly populations were collected from a succession of these crops in Western and Central Arizona regions. In most instances, the whiteflies in Western Arizona were significantly more susceptible to Danitol + Orthene than those in Central Arizona. Significant decreases were found in susceptibility to Danitol + Orthene during the 1996 season at three of the four locations in which multiple crops were monitored. This emphasizes that pyrethroid resistance levels can be increased in whitefly populations from any of the cotton, melons, or other winter vegetable crops evaluated. Therefore, management of pyrethroid resistance in Arizona cotton will require harmonizing resistance management efforts and specifically limiting pyrethroid use in the entire crop complex.
    • Side-Dress Temik® Effects on Lint Yields

      Husman, S. H.; Deeter, B.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Temik 15G was side -dressed at a rate of 7 lb./acre and 14 lb./acre and compared to an untreated check in two experiments in Buckeye, Az.. Treatments were made prior to the second in- season irrigation (June 3 and June 5) which was just prior to early bloom. Lygus counts were taken using a sweep net on weekly intervals for six weeks post application. The first experiment resulted in a significant increase of 123 lb. and 1241b. lint in both the 7 and 14 lb. rate treatment respectively over the untreated check. The second experiment resulted in a significant 102 lb. lint increase for the 7 lb. treatment with no significant difference for the 14 lb. treatment to the check.
    • Lint Yield Response to Varied Levels of Water Stress and Consumptive Water Use Requirements of Upland Cotton

      Metzler, F.; Husman, S.; Wegener, R.; Silvertooth, Jeff; University of Arizona, Maricopa County Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Lint yield response to varied Management Allowed Depletion Levels (MADL), and consumptive water use rates were determined for four upland cotton varieties (D&PL 5415, D&PL NuCotn 33B, D&PL 5816, and STV 474) at the Maricopa Agricultural Center. Four irrigation treatments based on MADL of 35% (Very Wet), 50% (Wet), 75% (Medium) and 90% (Dry) of available moisture were used to schedule irrigations after May 16. The Very Wet and Wet treatments showed statistically similar yields which were much greater than the Medium and Dry treatments. Irrigation return intervals of six to ten days from early June thru late July appeared to provide the greatest lint yields. Consumptive water use appears to reach its maximum during the peak bloom period of the fruiting cycle. Following peak bloom, water use gradually diminishes.
    • Conservation of Natural Enemies Relative to Use of Insect Growth Regulators for Control of Sweetpotato Whitefly

      Naranjo, Steven E.; Hagler, James R.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      As part of a large-scale, multi-institutional experiment in 1996 to examine and demonstrate strategies for management of Bemisia tabaci involving the use of two insect growth regulators (IGRs), we evaluated effects on the abundance and activity of native natural enemies. For parasitoids there were significant differences between insecticides regimes on 4 of 10 sampling dates. In general, parasitoid abundance and rates of parasitism were depressed in treatment plots receiving a rotation of conventional chemistry in comparison with those receiving IGRs. There was no apparent effect of any of the treatment variables on parasitoid emergence (immature survival). Results for arthropod predators are still preliminary, but densities were generally depressed in plots receiving a rotation of conventional insecticides in comparison with those receiving IGRs. These preliminary results suggest that use of IGRs for suppression of B. tabaci may help conserve populations of important natural enemies.
    • Evaluation of a Feedback Approach to Nitrogen and Pix Application

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      A single field experiment was conducted in 1996 at Maricopa, AZ to compare a scheduled approach (based on stage of growth) versus a feedback approach (based on vegetative status) to both nitrogen (1V) and mepiquat chloride (PIX™) applications on Upland cotton (Gossypium hirsutum L.). PIX feedback treatments were based upon fruit retention (FR) levels and height to node ratios (HNRs) with respect to established baselines. Scheduled and feedback PIX applications were made for a total of 0.75 and 1.25 pt./acre, respectively, with the scheduled treatments being initiated earlier in the fruiting cycle (early and peak bloom). Feedback PIK treatments consisted of a single 0.75 pt./acre application near peak bloom (approx. 2200 heat units after planting (HUAP), 86/55°F threshold). Scheduled applications of fertilizer N totaled 225 lbs. N/acre from three applications and feedback N treatments received a total of 135 lbs. N/acre from three applications. Treatments consisted of all combinations of scheduled or feedback applications of both N and PIX The highest lint yields were from a treatment receiving feedback N and PIX, but all treatment yields were not significantly different (P ≥ 0.05) from one another. From a practical (economic) standpoint, however, these treatments were different in terms of the differences of fertilizer N and the timing of the PIX applications required to produce comparable yields. Results from 1996 are consistent with 1993, 1994, and 1995 results from the same study.
    • Review of Irrigation Timing Stufies Conducted in 1995 and 1996

      Norton, E. R.; Silvertooth, J. C.; Brown, P. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Timing of the first, post plant irrigation is a critical management decision. With the more common reduced season type varieties being grown today water management becomes increasingly important and water stress must be avoided in order to obtain optimum yields In an effort to look at the effects of the timing of the first post plant irrigation two studies were established at both the Maricopa Ag. Center and the Marana Ag. Center in 1995 and 1996. Two treatments were established based upon evapotranspiration and soil water depletion with treatment one being the optimum irrigation timing and treatment two being delayed by approximately 7-10 days. Results showed decreased plant vigor and fruit retention as a result of the delayed irrigation treatment that continued the entire season. Yield reductions associated with the delayed irrigation were also observed in all four site years, two of which were significant.
    • Status of Whitefly Resistance to Insecticides in Arizona Cotton

      Dennehy, T. J.; Williams, L. III; Li, X.; Wigert, M.; Birdwell, E.; Silvertooth, Jeff; University of Arizona, Department of Entomology; Extension Arthropod Resistance Management Laboratory, Tucson , AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      We summarize a whitefly resistance crisis that culminated in 1995 in Arizona cotton and that prompted the development of an integrated resistance management strategy. The strategy incorporated two new major elements: once-per-year use of the insect growth regulators (IGRs), Knack® (pyriproxyfen) and Applaud® (buprofezin), and measures to delay use of pyrethroids for as long into the growing season as possible. A three-stage chemical use recommendation was formulated comprising IGRs (Stage I), other non-pyrethroid insecticides (Stage II), and synergized pyrethroid insecticides (Stage III). Results from use of the strategy in the 1996 season were very promising. Insecticide use for control of whiteflies was reduced substantially where IGRs were used. Statewide monitoring of whitefly susceptibility to key insecticides revealed significant reductions in resistance to synergized pyrethroids as well as to non-pyrethroid insecticides. Resistance to Danitol® + Orthene® was shown to decline sharply from the end of the 1995 season to early in the 1996 season at the Maricopa Agricultural Center. Use of Stage I materials (Knack® and Applaud®) and specific Stage II (non-pyrethroid) insecticides in 1996 resulted in only small reductions in susceptibility to synergized pyrethroids. However, one application of Danitol® + Orthene® yielded a large increase in resistance. These findings confirmed the value of the newly formulated resistance management strategy and indicated that resistance to the synergized pyrethroids can be managed if these insecticides are used sparingly. Additionally, evidence was obtained of collateral resistance buildup and decline in lygus bugs and whiteflies. Substantially reduced susceptibility of lygus bugs was documented in 1995, relative to 1994, coinciding with elevated insecticide use to control resistant whiteflies. Implementation of the 1996 whitefly resistance management program was correlated with increased lygus bug susceptiblity to the insecticides Orthene® and Capture® at most locations monitored throughout Arizona.
    • Whitefly Control Using Insect Growth Regulators

      Jech, L. E.; Husman, S. H.; Ellsworth, P. C.; Diehl, J. W.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Management of whiteflies with two insect growth regulators was compared with standard practices in grower managed cotton near Gila Bend, AZ. The IGRs, Knack (pyriproxyfen) and Applaud (buprofezin) were tested in a randomized complete block experiment with seven replicates. University ofArizona recommendations were followed to time insecticide applications. Following IGR applications, the nymphal populations remained near or below action thresholds (≤ 0.5-1.0 large nymphs per 3.88 cm² disk) from early August through early October. The standard practices treatments maintained the nymphal population through only early September, when populations sharply increased IGR treatments resulted in adult populations below University of Arizona action thresholds nearly as long as the nymphs. There was an adult population peak that followed a nymphal peak near the middle of September.
    • Evaluation of Late Season Pix™ Applications

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      The effects of late-season Pix™ on the growth characteristics and yield of Upland cotton was examined in this study. Three treatments were imposed late season (3447 HUAP), 1, a check plot, receiving no Pix™; 2 receiving 0.75 pt/acre, and 3; receiving 1 pt/acre. The imposed treatments did not have a statistically significant effect on plant growth characteristics or earliness, nor were there any significant overall yield differences detected among treatments.
    • Control of Pink Bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) with Biocontrol and Biorational Agents

      Gouge, D. H.; Smith, K. A.; Payne, C.; Lee, L. L.; Van Berkum, J. R.; Ortega, D.; Henneberry, T. J.; Silvertooth, Jeff; Western Cotton Research Laboratory, Phoenix, AZ; biosys, Inc., Columbia, MD; et al. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      At pre- sowing irrigation (mid-March), cotton fields were treated with two entomopathogenic nematode species; Steinernema riobravis and S. carpocapsae for control of diapausing Pectinophora gossypiella larvae. Pima S-6 cotton fields situated in Fort Hancock, Texas were treated at a rate of one billion nematodes per acre. Caged, diapausing larvae were buried in fields at a depth of one inch, in row tops and furrow bases. Nematodes were applied with a spray rig, fixed winged aircraft, or in furrow irrigation via a constant flow, battery box. Fields were irrigated after ground application, prior to aerial spraying and during furrow application. Caged larvae were recovered 48 hours after nematode application. All application methods resulted in uniform distribution of nematodes over the treated fields. No significant differences ir. larval mortality between nematode species or application method could be determined. However, aerial and furrow application methods gave consistently better parasitism of larvae compared to ground rig delivery. Larval mortality in cassettes buried in furrow bases was significantly higher than in row tops. Larval mortality ranged from 53.26-79.14 %. Both nematode species could be recovered 50 days post application. At pin-head square Frustrate® PBW pheromone bands (biosys, Inc.) were applied at 100 bands per acre placement rate (16 g a. i./acre), giving a target release of 115 mg gossyplure/acre/day. Capillary gas chromatography was used to analyze bands throughout the growing season. A uniform release profile indicated sufficient release of pheromone for 144 days after placement. Pink bollworm mating disruption was monitored in three ways: 1. Delta 2 traps were positioned throughout the farm, forming a continuous trap line. Significantly larger numbers of moths were recovered form untreated zones. 2. Virgin female moths were placed in mating stations at dusk. At sun rise moths were collected and later dissected for spermatophores. Significantly higher mating activity occurred in untreated fields (p= 0.000). 3. Green bolls were collected at random and examined for larvae. Significantly higher infestation levels existed in untreated zones. At harvest (November), seed cotton yields were weighed using trailer scales. Higher yields were recovered from pheromone (1,864 lb/acre), and pheromone + nematode fields (1,712 lb/acre), than control fields (1,450 lb/acre). However, due to large variations between fields, the differences were not statistically significant (p = 0.436).
    • Upland Regional Cotton Variety Test at the Maricopa Agricultural Center, 1996

      Hart, G. L.; Nelson, J. M.; Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Twenty five upland cotton varieties were grown 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.
    • Evaluation of Planting Date Effects on Crop Growth and Yield for Upland and Pima Cotton, 1996

      Silvertooth, J. C.; Norton, E. R.; Brown, P. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Three field studies were conducted in 1996 at the Maricopa (1,175 ft. elevation), Marana (1,974 ft. elevation), and Safford (3,000 ft. elevation) Agricultural Centers to evaluate the effects of three planting dates on yield and crop development for Upland and Pima varieties. Planting dates ranged from 19 March to 16 May and also 437-1199 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.
    • Evaluation of Planting and Dating Effects on Crop Growth and Yield for Upland and Pima Cotton, Marana, 1995

      Norton, E. R.; Silvertooth, J. C.; Brown, P. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      A single field study was conducted in 1995 at the Marana Agricultural Center (2000 f elevation) to evaluate the effects of three planting dates on yield and crop development for one Pima and two Upland varieties. Planting dates ranged from 6 April to 18 May (469 -931 HU /Jan 1 86/55° F thresholds). Crop monitoring revealed vegetative growth tendencies with later plantings. General trends showed decreasing lint yield with the later (18 May) plantings for all varieties. Early plantings (6 April) however, for both Pima S-7 and DPL 20 resulted in slightly lower yields than the later two planting dates. This reduced yield for planting date 1 can be explained by extremely cool weather conditions which occurred immediately after planting and in-season fruit loss which impacted the final fruit retention levels.
    • Pima Cotton Regional Variety Trial, Safford Agricultural Center, 1996

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Twenty three 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 1996 was OA 322 with a yield of 1282 pounds of lint per acre. It was followed by six other Olvey varieties and DP 9911, all Adding over 1000 pounds of lint per acre. The average yield from this trial was more than 200 pounds per acre higher than the previous trial Yield and other agronomic data as well as fiber quality data are contained in this paper.
    • Pima Regional Variety Test at the Maricopa Agricultural Center, 1996

      Hart, G. L.; Nelson, J. M.; Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Eighteen Pima varieties and experimental strains were grown in a replicated trial at the Maricopa Agricultural Center. Lint yield, boll size, lint percent, plant height and fiber data are presented in this report.