• Defoliation of Pima and Upland Cotton at the Safford Agricultural Center, 1993

      Clark, L. J.; Carpenter, E. W.; Odom, P. N.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Experiments were effected on both Pima and upland cotton to compare the defoliation effects of Ginstar, Starfire 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.
    • Initial Post Plant Irrigation Effects on Low Desert Upland Cotton Yields Using Leaf Water Potential Measurements

      Husman, S. H.; Barrot, D. J. Jr.; O'Leary, J. W.; Moore, M.; Wegener, R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Leaf water potential (LWP) measurements using a pressure chamber were used to determine optimum timing of the first irrigation following planting on Upland cotton in 1992 and 1993. Previous studies have indicated that leaf water potentials are dependent on the vapor pressure deficit (VPD) of the surrounding air. As a result, the VPD was accounted for in the development of a Leaf Water Potential Index (LWPI). The field studies consisted of three irrigation treatments with four replicates arranged in a randomized complete block design (RCB). Targeted treatment thresholds were 0.15 LWPI (wet), 0.30 LWPI (medium), and 0.45 LWPI (dry). Timing of the first irrigation for the 1992 study occurred at 36, 53, and 63 days after planting. Timing of the 1993 first irrigation occurred at 50, 61, and 77 days after planting for the wet, medium, and dry treatments respectively. There were no significant lint yield differences between irrigation treatments in both 1992 and 1993.
    • Upland Cotton Variety Resposne to Row Spacing

      Husman, S. H.; Silvertooth, J. C.; Jech, L. E.; Wegener, R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      An Upland cotton row spacing study evaluation 30 in. vs. 38 in. rows was conducted in the Gila Valley of western Maricopa County in 1993. In addition, six Upland varieties were also evaluated on both the 30 and 38 in. row configurations. There were no row spacing differences in yield among five of the six varieties. Sure Grow 1001 had significantly lower lint yields when produced on 30 In. rows. DPL 5415 had significantly higher lint yields that the other five tested varieties on 38 in. rows. There were no variety differences in the 30 in. rows.
    • Numerical and Binomial Sequential Sampling Plans for 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), 1994-03)
      Fixed-precision numerical and binomial sequential sampling plans are reported for adults of Bemisia tabaci (Strain B) on cotton. Both plans are based on whole leaf sample units from the fifth mainstem node (counted from the terminal). Numerical sampling plans allow for the efficient estimation of adult population density. Numerical sampling stop lines are presented relating the cumulative number of adults counted to the number of leaves examined for two levels of statistical precision. Binomial plans were developed to allow classification of adult population density for pest management decision -making application. These plans were devised for three action threshold levels; 5, 10 or 15 adults per leaf Binomial sampling stop lines are presented relating the cumulative number of infested leaves to the number of leaves examined as an aid for determining the need for population suppression.
    • Evaluation of a Feedback vs. Scheduled Approach to PIX Application

      Fletcher, D. C.; Silvertooth, J. C.; Norton, E. R.; Unruh, B. L.; Lewis, E. A.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Two field experiments were conducted in 1993 in Arizona to compare a scheduled approach (based on stage of growth) versus a feedback approach (based on vegetative status) to mepiquat chloride (PIX™) applications on Upland cotton (Gossypium hirsutum L.). PIX feedback treatments received no PIX applications due to plants lacking vegetative tendencies based upon height:node ratios (HNRs) and established baselines. Scheduled PIX applications ranged from 0.5pt. /acre to 0.75 pt./acre, and were applied at early bloom (approx. 1500 heat units after planting (HUAP), 86/55 °F threshold) and post early bloom (approx. 2000 HUAP). PIX treatments did consistently reduce plant heights compared to an untreated check. Statistically significant differences (P ≤ 0.05) in lint yield were observed among the treatments (feedback vs. scheduled)at the Safford location only. Evidence from these studies do reinforce the use of a feedback approach from the standpoint of conserving inputs and maintaining optimum growth control.
    • Influence of Pink Bollworm, Pectinophora Gossypiella, (Saunders) (Lepidoptera : Gelechiidae), Female Age on Oviposition Capacity and Egg Hatchability

      El-Lissy, O.; Al-Beltagy, A.; Antilla, L.; Leggett, J. E.; Silvertooth, Jeff; Arizona Cotton Research and Protection Council, Tempe, AZ; Plant Protection Research Institute, Cairo, Egypt; USDA -ARS- Western Cotton Research Laboratory, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Oviposition capability and e 4: hatchability of three laboratory reared strains of pink bollworm, Pectinophora gossvpiella, (Saunders) were evaluated to determine the effect of age on the female reproductive capacity. From comparisons of various female ages in terms of the amount of eggs deposited and the level of ex hatchability, it was concluded that young females (3-6 days old) had the highest potential for oviposition and that their eggs had the highest percentages of hatchability.
    • The Pegasus Rapid Plowdown System: A New Concept in Cotton Tillage

      Thacker, Gary W.; Coates, Wayne E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      This new concept in tillage is to open a deep, temporary slot next to the cotton row and to insert the stalks and/or roots into the slot before the soil falls back in. The Pegasus Rapid Plow Down System is a relatively simple implement which offers good residue burial and reliability. Our limited field test data indicate that this invention requires less energy and field work time than conventional tillage systems.
    • Plant Population Evaluation for Upland Cotton

      Silvertooth, J. C.; Norton, E. R.; Stedman, S. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
    • 1993 Weather Conditions

      Brown, P.; Russell, B.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Abnormally high January and February rainfall will certainly be the most remember meteorological feature of 1993. This rainfall led to extensive flooding along the Gila River and its tributaries, and delayed field preparation in many areas. However, once the winter rains ended, weather conditions proved very favorable for cotton production. Warm, dry spring weather helped get the cotton crop off to a good start. Moderate summer temperatures and a late monsoon provided excellent weather conditions for setting fruit. The relatively short monsoon period was followed by an extended period of mild, dry weather which provided excellent conditions for finishing the crop. The only blemish on the fall weather pattern was a period of heavy rainfall in mid - November which delayed field operations in much of central Arizona.
    • Potential for Pink Bollworm Control with Entomopathogenic Nematodes

      Lindegren, J. E.; Henneberry, T. J.; Raulston, J. R.; Forlow Jech, L. J.; Valero, K. A.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      The susceptibility of late instar pink bollworm (PBW), Pectinophora gosspiella (Saunders), larvae to two species of Steinemema was evaluated in small scale field tests in spring and summer of 1993. In the spring PBW mortality at 15 infective juveniles /cm² for S. carpocapsae and S. riobravis was 87 and 89 %, respectively. In midsummer, mortalities with S. riobravis were significantly greater than with S. carpocapsae at the four concentrations tested. A simple method was developed for small scale field testing and efficacy monitoring for PBW and other soil associated insects.
    • A Community-wide Approach to Whitefly Management

      Diehl, J. W.; Ellsworth, P. C.; Husman, S. H.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      An extension supported, grower controlled, community pest management group was initiated in the Laveen and Tolleson communities of Arizona with the management of sweetpotato whitefly (SPWF) as its initial focus. The three functions of this group were awareness, communication, and cooperation. Increased awareness and communication of pest management problems and solutions were achieved through regular meetings and newsletters. Community cooperation took the form of a community-based overwintering survey and a sticky trap network. These two cooperative activities served both an educational and a research function. From the overwintering survey and the sticky trap network, growers learned about the overwintering habits and movement dynamics of whiteflies in their area, the limits of sticky traps for SPWF detection, the need for the reduction of SPWF populations before they move onto cotton. and the need for careful infield sampling of SPWF populations.
    • Dry Matter Accumulation by Upland and Pima Cotton

      Unrah, B. L.; Silvertooth, J. C.; Steger, A. J.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Several investigations of dry matter accumulation by Upland cotton (Gossvpium hirsutum L.) have been conduced, however no investigations of this type have included American Pima cotton (G. barbadense L.). We conducted a study to describe the total dry matter accumulation and partitioning of that dry matter into various plant parts for both Upland and Pima cotton. During the growing seasons of 1990, 1991, and 1992 at two south-central Arizona locations, both Upland (var. DPL 90) and Pima (var. S-6) cotton were grown. Beginning 14 to 20 d after emergence, whole cotton plants were removed and cotton plants were separated into stems, leaves (including petioles), burs (carpel walls), lint, and seeds. The bur fraction, also included squares, flowers, immature bolls, and burs from mature bolls, Regression analyses was used to model nutrient uptake as a function of both days after planting (DAP) and heat units after planting (HUAP). Regression analyses indicated that HUAP was equally good, and in most cases superior to using DAP to model dry matter accumulation and partitioning within both Upland and Pima cotton. The general patterns of dry matter partitioning for Upland and Pima cotton are similar. However, Upland and Pima differ in the relative amount of dry matter incorporated into reproductive (bur, seed, and lint) and vegetative (leaf and stem) structures. Upland cotton produced 3527 lb /acre more total dry matter than Pima cotton. At the end of this study the vegetative /reproductive ratio for Upland was 83% compared to 70% for Pima. Upland was also more efficient at partitioning lint dry matter within the total dry matter of the reproductive structures. Dry matter incorporated into reproductive structures was 23% lint for Upland, compared to only 14% lint in Pima cotton. In summary, Upland placed more total dry matter into reproductive structures, and of the amount placed into reproductive structures, a greater proportion was incorporated into lint, when compared to Pima cotton.
    • Short Staple Variety Demonstrations, Graham County, 1993

      Clark, Lee J.; Cluff, Ronald E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Two on farm, replicated short staple variety demonstrations were established in 1993. Twelve varieties were evaluated in one location and fifteen varieties were evaluated at the other. Delta Pine 90 was the highest yielding variety at one location with a yield of 1387 pounds of lint per acre and Stoneville LA 887 was the highest yielding variety at the other location with a yield of 1134 pounds of lint per acre.
    • Short Staple Variety Trials in Cochise County, 1993

      Clark, Lee J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Variety trials were grown at two locations and with two different sets of short staple varieties. One trial, north of Kansas Settlement, tested nine acalas and one rust resistant variety from Mexico. The other trial, south of Kansas Settlement and east of Pearce, tested three acalas and nine upland varieties. Top yielding varieties were Maxxa, in the acala trial and DPL 2056 in the upland trial. Yields were lower than expected due to adverse weather conditions, including hail.
    • Chemical Control of the Sweetpotato Whitefly in Cotton

      Watson, T. F.; Telles, A.; Peña, M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Various registered and experimental insecticides were evaluated for sweetpotato whitefly (Bemisia tabaci Gennadius) control in several field experiments at Yuma, Arizona in 1993. 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.
    • Short Staple Cotton Variety Trial, Safford Agricultural Center, 1993

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Fifty three short staple varieties were grown in a replicated field trial on the Safford Agricultural Center. HS SAL 10, a long season variety, was the highest yielding variety in the trial with a lint yield of 1772 pounds per acre. Average yields in this trial were lower than in 1992, even though there were more heat units during the growing season. HVI data for the varieties in the trial are included in this report.
    • Long Staple Cotton Variety Trial, Safford Agricultural Center, 1993

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Sixteen long staple cotton varieties (including 4 Pima experimental lines) were tested in a replicated small plot trial on the Safford Agricultural Center. Plots were machine harvested twice to determine yield and percent first pick Small hand samples were taken to determine boll size, percent lint turnout and fiber qualities. Pima S-6 was the highest yielding variety with 1110 pounds per acre of lint. Five of the sixteen varieties yielded over 2 bales per acre. A new variety OA 312 looks particularly promising with yield very close to S-6, fiber quality better than S-6 and an earliness that approaches that of S-7.
    • Preliminary Field Evaluation of an Insect Growth Regulator, Buprofezin, for Control of the Sweetpotato Whitefly, Bemisia Tabaci

      Ellsworth, P. C.; Meade, D. L.; Odom, Phillip; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Two rates of buprofezin and a combination, buprofezin + endosulfan, were compared against Ovasyn® and the standard pyrethroid combination Danitol® + Orthene®. Targeted pests were all stages of the sweetpotato whitefly (SPWF). Danitol + Orthene was the most effective treatment against all SPWF stages. All buprofezin treatments, including the buprofezin + endosulfan combination, were moderately effective against all SPWF stages relative to the untreated check, while Ovasyn had control levels similar to the untreated check. Danitol + Orthene had the highest yield at 4030.2 lbs seed cotton/A, and buprofezin + endosulfan had the second highest yield, 2172 lbs/A. All other treatments yielded amounts similar to the untreated check, 863.0 lbs/A. Effects of these control practices on beneficial and other non- target arthropods have not yet been analyzed. Lygus populations were extreme in this test and favored the Danitol + Orthene treatment over the SPWF -specific buprofezin treatments.
    • Varietal and Nitrogent-level Effects on Sweepotato Whitefly Populations in Cotton

      Watson, T. F.; Silvertooth, J. C.; Tellez, A.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Four cotton varieties, each differing in leaf pubescence, and three nitrogen (N) levels were investigated for effects upon development of SPWF populations. The N treatments appeared to have no effect upon population development. However, there was a direct correlation of increased SPWF numbers with increased hairiness. Both DPL 5415 and SALCOTIO had significantly lower seasonal means of all stages than did the more hairy varieties of CB1135 and STV453.
    • Sweetpotato Whitefly (Bemisia Tabaci Gennadius) Population Relationships to Cotton Yield and Quality

      Chu, C. C.; Henneberry, T. J.; Akey, D. H.; Prabhaker, N.; Perkins, H. H.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Sweetpotato whitefly (SPWF) Bemisia tabaci Gennadius strain B has been a devastating pest of cotton in Arizona and California in recent years. Management systems involving cultural procedures, SPWF population monitoring crop sanitation, crop sequencing chemical control and other technology are developing slowly. SPWF population information in relation to cotton yield and quality losses are urgently needed Preliminary studies with cotton insecticide treatments initiated each week from shortly after cotton seedling emergence to late in the cotton season were conducted at the Irrigated Desert Research Station, Brawley, CA in 1993. The results suggest significant correlations for numbers of SPWF per leaf disc from cotton leaves vs. cotton yield and lint stickiness. Cotton lint yield was negatively correlated to all stages of SPWF populations (-0.783 or higher). Lint stickiness was high positively correlated to SPWF populations (0.707 or higher) and cotton defoliation was positively correlated to SPWF populations (0.876 or higher).