• 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)
    • Novel Pyrethroid Combinations for Control of Sweetpotato Whitefly and Their Impact on Lygus

      Ellsworth, P. C.; Meade, D. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Combinations of two insecticides, often a pyrethroid with an organophosphate, have been used more successfully in sweetpotato whitefly (SPWF) control programs rather than single insecticides when SPWF populations are chronically high. Ten combinations of various insecticides were compared for their effectiveness against all SPWF stages. Applications were by ground, broadcast over -the -top of plots 12 rows x 40 ft on five application dates. Three sampling methods were used: leaf turns and sweeps for adult counts, and microscopic leaf counts for immature stages. Danitol® +Orthene® emerged as the most consistently effective combination on all SPWF stages when compared to the untreated plots. Over all dates and SPWF life stages, the combinations were ranked according to the following order of descending efficacy: Danitol + Orthene 5 Danitol + Lorsban® Karate® + Penncap -M® = Scout Xtra® + Orthene = Asana® + Curacron® = Asana + Orthene < Asana + Phaser® = Scout + Phaser = Asana + Lorsban = Asana + Vydate® < untreated check. Yields were also affected by the combinations, but attributed to SPWF and Lygus suppression. Orthene treatment combinations yielded consistently greater than other entries and was likely due to superior Lygus control and at least average SPWF control. The Asana + Vydate was ranked among the best in Lygus control but low in SPWF control, while Karate + Penncap, Danitol + Lorsban, and Asana + Curacron were ranked high in SPWF control but low in Lygus control. The remaining treatments were more or less intermediate in SPWF and Lygus control. Rankings of these combinations for Lygus control were in the following order of descending efficacy: Asana + Vydate = Scout + Orthene = Asana + Orthene = Danitol + Orthene < Scout + Phaser = Danitol + Lorsban = Karate + Penncap < Asana + Curacron < Asana + Phaser = Asana + Lorsban < untreated check.
    • Irrigation Efficiencies and Lint Yields of Upland Cotton Grown at the Maricopa Agricultural Center, 1993

      Sheedy, Mike; Watson, Jack; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      The computer program AZSCHED, with weather data obtained from AZMET, was used to schedule irrigations for a yield trial of early season Upland Cotton (DPL 20) at the Maricopa Agricultural Center. Cotton lint yields were compared between plots from five treatments involving five irrigation efficiencies (50 %, 65 %, 75 %, 90% and 110 %). As in previous years, a potassium bromide tracer was applied to select areas in each plot to monitor the movement of water and nitrates down the soil profile. The total amount of fertilizer as nitrogen applied in two split applications and sidedressed was 100 #/a. The total amount of water applied to the plots ranged from 42.7" for 50% to 26.6" for 110% (deficit) irrigation efficiency. The plots were harvested on October 5, 1993. There was a significant difference in lint yield between the irrigation efficiency treatments. The 50% irrigation efficiency treatment produced 1190 # lint /acre while the 110% efficiency produced 883 # lint /acre.
    • 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.
    • 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.
    • Potassium Fertilization of Upland and Pima Cotton

      Unruh, B. L.; Silvertooth, J. C.; Galadima, A.; Clark, L. J.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      In a continuing effort to assess the agronomic necessity of potassium (K) fertilization in Arizona cotton (Gossypium spp.) production, one new and two on-going (Maricopa and Safford Ag. Centers), K fertility studies were conducted in 1993. They included locations ranging from western (Yuma) to eastern (Safford) Arizona, with both Upland (G. hirsutum L.) and American Pima (G. barbadense L.) cotton, using soil and foliar applications of K. The results indicated that there was no response to the added K at any of the locations by either Upland or Pima cotton.
    • 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.
    • 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 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.
    • 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.
    • Nutsedge Control in Cotton Using Norflurazon (Zorial Rapid 80): A Progress Report

      McCloskey, William B.; Dixon, Gary L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Field experiments were conducted in 1992 and 1993 to determine the crop safety and efficacy of norflurazon applications for control of purple and yellow nutsedge in cotton. Norflurazon was applied preplant-incorporated (PPI) or in two applications, PPI and postemergence (POST) when cotton was 3 to 4" tall. As the PPI norflurazon application rate increased from 0.5 to 0.75, 1.0, and 1.25 lb a.i./A, early season nutsedge control increased from 29 to 49, 58, and 76% of control. Early season weed control declined after about 6 weeks. POST emergence applications of norflurazon prolonged the period of nutsedge control. Data collected 71 and 21 days after the PPI and POST applications, respectively, showed that the 0.5 +1.5, 0.75 +1.25, and 1.0+1.0 lb a.i./A (PPI +POST) treatments resulted in 85, 76, and 73% control of nutsedges. Nutsedge control declined throughout the season with the 0.5 +1.5, 0.75 +1.25, and 1.0+1.0 lb a. i./A split applications all resulting in about 27% control 3 months after the POST applications. PPI rates 1.5 to 2 times the labeled rate for a particular soil type caused cotton injury in several experiments in the 1993 cotton season although no injury was observed in the 1992 season.
    • The Use of AZSCHED to Schedule Irrigation on Cotton, Safford Agricultural Center - 1993

      Clark, Lee J.; Carpenter, Eddie W.; Slack, Donald C.; Martin, Edward C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      An irrigation scheduling trial was implemented on both long and short staple cotton on the Safford Agricultural Center in 1993. It is a continuation of studies initiated in 1991, where plots were irrigated when they reached 40 %, 50% and 60% soil water depletion level as predicted by the AZSCHED software. Results for this study are given as well as a summary of the three year study.
    • Boll Maturity Estimates for Mid- and Late-Season Flowering Dates in Arizona

      Brown, P. W.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Boll maturity dates and the number of days after flowering for a boll to reach physiological maturity were estimated for six representative flower dates: 15 July, 29 July, 12 August, 26 August, 9 September and 23 September. Estimates were developed for 28 locations using historical heat unit (HU) information using the assumption that 600 HUs are required after flowering for a boll to reach physiological maturity. The results are presented in both tabular and graphical forms.
    • Validity of the Pinhead Square Treatment Program for Pink Bollworm Suppression and Impact of Several Insecticides on Arthropod Fauna in Cotton

      Ellsworth, Peter C.; Meade, Donna L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      A limited chemical control tactic known as pinhead square treatment has gained recent Favor as a component of pink bollworm population management. The strategy has economic and ecologic goals of using reduced insecticides early in the season (to include lower rates, half the acreage, and less potent chemistry) in order to reduce later season risk of pink bollworm infestations. This strategy also depends in part on the cultural tactic which results in "suicidal emergence" of overwintering pink bollworms through optimal planting date management. The combination of these tactics has been used in the past to overcome boll weevil populations area-wide. This study is focused on the evaluation of this system as a basis for pink bollworm suppression. Though only preliminary is presented here, it is clear that there are numerous insects impacted by this practice which interact in complex ways to influence pest populations of all kinds. Furthermore, the fate of such a practice in any production system is also influenced by the specific chemical agent used. This experiment details the use of four different classes of insecticide chemistry as well as one bioinsecticide. The experiment has been duplicated in 1993; however, only 1992 data are shown here.
    • Practical Uses of Crop Monitoring for Arizona Cotton

      Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
    • Arizona Upland Cotton Variety Testing Program

      Silvertooth, J.; Norton, R.; Clark, L.; Hood, L.; Husman, S.; Cluff, R.; Stedman, S.; Thacker, G.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Ten field experiments were conducted across the cotton growing areas of Arizona in 1993 for the purpose of evaluating Upland cotton varieties in terms of adaptability and performance. Five commercial cottonseed companies participated in the program. Two varieties were submitted from each company at each location. Experiments were conducted on grower -cooperator fields in each case. Locations used in the program spanned the range of conditions common to cotton producing areas of the state from about 500 ft. to 4,000 ft. elevation. Results indicated a broad range of adaptability and competitiveness on the part of each of the participating companies and their representative varieties. Each of the companies offers a compliment of varieties that can serve to match various production strategies commonly employed in the state as well as showing a strong capacity to be regionally adaptive.
    • Methanol Effect on Upland Cotton

      Husman, S. H.; McCloskey, W. B.; Molin, W. T.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      The effects of foliar applied methanol on Upland cotton were measured in a large field study in Phoenix, AZ. An untreated check was compared to weekly applications of 30% methanol, 30% methanol plus 1% Urea and 0.1 % Fe EDTA, and 1% Urea and 0.1% Fe EDTA. Plant growth and development, photosynthesis, transpiration, soil water use and lint yields were measured. There were no differences in any of the measured variables between treatments.
    • Defoliation Research on Pima and Upland Cotton at the Maricopa Agricultural Center in 1993

      Nelson, J. M.; Hart, G.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Field studies were conducted at the Maricopa Agricultural Center to evaluate the effectiveness of selected defoliation treatments on Pima and upland cotton under warm and cool weather conditions. Weather conditions during September tests were warm and dry while in late October tests weather was very cool. Defoliation treatments resulted in a high percentage of leaf desiccation in a test on 10 September. Ginstar and Dropp + Def treatments gave good defoliation of cotton in a 23 September test. In October tests, defoliation treatments were effective on Pima cotton but upland cotton as difficult to defoliate. Ginstar defoliant was generally as effective as the Dropp + Def treatment at the rates tested.
    • Defoliation Research on Pima and Upland Cotton at the Marana Agricultural Center in 1993

      Nelson, J. M.; Barney, G. F.; Hart, G. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      A field study was conducted at the Marana Agricultural Center to evaluate the effectiveness of ground rig applied defoliant treatments on Pima and upland cotton under cool weather condition. The experimental defoliant Ginstar and the combination treatment of Dropp + Def resulted in good defoliation 14 days after application.
    • Pima Cotton Genetics

      Percy, R. G.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      A feasibility study of short season management in Pima cotton, using short season genotypes, was initiated in 1993. Four short season genotypes, a full season check, and a short season check were evaluated in replicated tests under short season and full season regimes. In this first preliminary year of data, no significant yield loss could be attributed to management regime or to earliness of genotypes. Three of the putative early maturing genotypes exceeded the full season Pima S-7 check in yield. Results were contrary to expectations. The short season test is planned for repeat in 1994. An investigation of a virescent mutant discovered in 1990 (CM-1-90) was conducted in 1991, 1992, and 1993. Crosses of the mutant to Pima S-6 to determine inheritance, and to various virescent mutants to determine allelism produced results which were anamolous to normal, nuclear inheritance. Reciprocal crosses to PS-6 and to various virescent mutants confirmed that the new mutant was cytoplasmicaly inherited.