• 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.
    • 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.
    • Methanol Treatments on Pima and Upland Cotton

      Nelson, J. M.; Nakayama, F. S.; Flint, H. M.; Garcia, R. L.; Hart, G. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      A study was conducted at the University of Arizona Maricopa Agricultural Center, Maricopa, AZ in 1993 to determine the effect of foliar applications of methanol on cotton physiology, growth, yield and whitefly infestation. Six applications of a 30% methanol solution during bloom had no effect on plant height, boll weight, lint yield or earliness of Pima S-7 (Gossvpium barbadense L.) or upland DP5415 (Gossvpium hirsutum L.) cotton. No effect of methanol on photosynthesis or photorespiration was observed. A significant reduction in sweetpotato whitefly nymph population occurred on DP5415 cotton seven weeks after methanol treatment began. This study provided no evidence that methanol can be used to improve cotton production.
    • Nitrogen Management Experiments for Upland and Pima Cotton, 1993

      Silvertooth, J. C.; Norton, E. R.; Unruh, B. L.; Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Two field experiments were conducted in Arizona in 1993 at two locations (Maricopa and Safford). Both experiments have been conducted for five consecutive seasons, with consistent plot locations. 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. Results at both locations 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 effects of N fertility levels have been consistently evident in crop maturity and its relationship to lint yields.
    • Nitrogen, Phosphorus, and Potassium Uptake by Upland and Pima Cotton

      Unruh, 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 nitrogen (N), phosphorus (P), and potassium (K) uptake by Upland cotton (Gossypium 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 N, P, and K uptake and the partitioning of each nutrient 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. The appropriate analyses for total N, P, and K were determined on each fraction (except lint). 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 total nutrient uptake and partitioning within both Upland and Pima cotton. In every case there was close agreement between the predicted and actual total nutrient uptake. For Upland cotton the actual total N, P, and K uptake was 199, 29, and 250 kg ha⁻¹ and the predicted total N, P, and K uptake was 199, 29, and 255 kg ha⁻¹, respectively. For Pima cotton the actual total N, P, and K uptake was 196, 29, and 215 kg ha⁻¹ and the predicted was 210, 29, and 229 kg ha⁻¹, respectively. The pattern of nutrient partitioning in Upland cotton were similar to the findings of others and Pima showed the same general patterns of partitioning as Upland cotton. Seeds were a major sink of nutrients. Nutrient uptake in seeds resulted in decreasing uptake in leaves and stems. Presumably, due to mobilization of nutrients from those parts to the seeds during seed development. The nutrient requirements to produce 100 kg lint ha' for Upland cotton was 15, 2.2, and 19 kg ha⁻¹ for N, P, and K, respectively and was 20, 3.0, and 22 kg ha⁻¹, respectively for Pima cotton.
    • 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.
    • 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.
    • 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 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.
    • Physiological Response of Cotton to Terminal Damage

      Unruh, B. L.; Silvertooth, J. C.; Hanline-Boerum, T. R.; Marlow, B. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      The terminal of a cotton (Gossypium spp.) plant controls the growth of lower vegetative branches through the production of hormones. If the terminal is damaged then the lower vegetative branches will begin to grow and produce new mainstems. The objective of this study was to determine what delays, if any, are caused by damage to the terminal meristem. Three identical experiments (differing only by their planting date) were conducted in the greenhouse in which Upland (G. hirsutum L., var. DPL 5415) cotton was planted in 24 pots and allowed to grow until the majority of the plants reached the four true -leaf stage. At that point half of the plants had their terminals removed. Twice weekly series of plant measurements were recorded for each plant in the study. Measurements taken included the number of mainstem nodes, plant height, node of the first fruiting branch (FFB), days after terminal removal (DATR) until the appearance of the FFB, node of the first bloom, and DATR until the appearance of the first bloom were recorded. Removal of the terminal significantly increased the node of the FFB, the node of the first bloom, and the occurrence of each of these by 7 to 8 days. Regression analysis was used to model plant height and the accumulation of mainstem nodes as a function of DATR. Results showed that plants with terminals removed did reach the same height as the control group. However, the plants with their terminals removed never accumulated as many mainstem nodes as their counterparts in the control group.
    • 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.
    • Pima Cotton Improvement

      Percy, R. G.; Turcotte, E. L.; Ray, I. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Pima experimental strains P73, P75, P76, P77, and the cultivars Pima S-6 (PS-6) and Pima S-7 (PS-7) were grown in replicated regional tests at twelve locations across the Pima belt in 1993. Tests were machine harvested for yield determination, plant heights were measured, and lint samples were collected for fiber analysis. Considerable genotype by environment interaction for yield potential occurred across tests in 1993. Across all locations, the strain P76 ranked first in yield followed by the cultivar PS-7 and strain P75. Strains P73 and P76 produced fiber of equal or greater length, strength, and elongation than PS-7. Plant heights were greatest for the entries PS-6 and P75. Entries PS-7 and P73 were intermediate in height, while P76 and P77 were the shortest of the entries tested. Considering yield and fiber properties concurrently, P76 was the superior entry of the 1993 tests.
    • Pima Regional Variety Test Maricopa Agricultural Center, 1993

      Hart, G.; Nelson, J. M.; Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Twelve Pima varieties and experimental strains were grown in a replicated trial at the Maricopa Agricultural Center. Lint yield, boll size, lint %, gin turnout %, plant population and fiber property data are presented in this report.
    • Plant Growth Regulator Studies at the Safford Agricultural Center, 1993

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Results from several tests both on the Safford Agricultural Center and off are reported on in this paper. Methano4 Cytokin, X-Cyto, Temik and Amplify-D treatments results are included and discussed.
    • 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)
    • 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.
    • 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.
    • Practical Uses of Crop Monitoring for Arizona Cotton

      Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
    • 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.
    • Seasonal Distribution of Cotton Leafperforator: Pheromone Dispenser Persistence and Effect of Trap Height on Moth Catches in Pheromone Baited Traps

      Leggett, J. E.; Henneberry, T. J.; White, R. D.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      The cotton leafperforator (CLP) Bucculatrix thurberiella Busck. is a sporadic pest in cotton fields of southwest desert area. The cotton leafperforator sex pheromone was identified and synthesized by Hall et al. (1992), thus providing a sensitive method for detecting CLP moths. Tests were conducted in 1992 and 1993 to determine the effective life of CLP polyethylene pheromone dispensers, correlate CLP male moth catches to cotton field infestations, determine the seasonal distribution, and effect of trap height on moth catches. The polyethylene pheromone dispensers were effective for about 4 weeks. The best correlation coefficients for 1993 data, were obtained by comparing CLP moth catches per night to main stem leaf damage at 6 node position from top of plants at field edges. Horseshoe stage CLP per leaf and trap catches had the highest correlation coefficient, r= 0.78. There was more than twice as much CLP damage to leaves at field edges when compared to leaves 10 m into the field. The first CLP moth capture occurred in early to late July and increased rapidly each year in August to 100 to 200 per trap night, but was variable in September, with a high of 300 and a low of 9 per trap night. CLP- baited delta traps placed 0.3 m above ground caught more moths than traps placed at greater heights from 11 to 21 August.