• Cotton Defoliation Evaluations, 1993

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Two field experiments were carried out in representative cotton producing areas of Arizona to evaluate the effectiveness of a number of defoliation treatments on Pima cotton. These experiments were conducted at Coolidge and Marana. The treatments employed principally consisted of relatively new materials available in Arizona, and were compared to current standard treatments. All treatments showed promise in terms of effectiveness and the results provide a basis for use recommendations in 1995.
    • Evaluation of a Feedback Approach to Nitrogen and Pix Application

      Silvertooth, J. C.; Norton, E. R.; Unruh, B. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A single field experiment was conducted in 1994 at Maricopa, AZ to compare a scheduled approach (based on stage of growth) versus a feedback approach (based on vegetative status) to both nitrogen (N) and mepiquat chloride (PIX™) applications on Upland cotton (Gossypium hirsutum L.). PIX feedback treatments were based upon fruit retention (FR) levels and height: node ratios (HNRs) according to established baselines. Scheduled PIX applications were made for a total of 1.0 pt./acre over two applications, with feedback PIX treatments receiving a single 0.5 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 four applications and feedback N treatments received a total of 135 lbs. N/acre from three 45 lb. N/acre 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 and a treatment receiving scheduled N and PIX, which were not significantly differencent (P ≤ 0.05) from one another. From a practical standpoint, however, these treatments were very different in terms of the magnitude in differences of fertilizer N and PIX required to produce comparable yields.
    • Effect of Planting Date on Yield of Upland and Pima Cotton Varieties at Marana

      Unruh, B. L.; Silvertooth, J. C.; Brown, P. W.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A single field experiment was conducted at Marana Agricultural Center (2000 fl elevation) to evaluate the response of one Pima (G. barbadense L) and two Upland (Gossypium hirsutum L.) cotton varieties to three different planting dates. Planting dates ranged from 12 April to 16 May. In general there was decreasing lint yield with later planting dates.
    • Multiple Plant Growth Regulator Use on Short Staple Cotton

      Hood, L. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A field trial was conducted during the 1992 & 1993 growing seasons to evaluate the activity of Cytokin and Pic applied alone or in combination to short staple cotton. The Cytokin treatment significantly increased tint yield over the other treatments in 1992. There were no statistically significant seed cotton differences between the non - treated check and any treatment in 1993. Fruit retention remained high throughout 1992 and very high throughout the 1993 season. Under high fruiting conditions, use of a plant growth regulator would not normally be recommended.
    • Defoliation Research on Upland and Pima Cotton at the Maricopa Agricultural Center in 1994

      Nelson, J. M.; Hart, G. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      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. Air temperatures were high for tests conducted on 16 and 22 September and cool for tests conducted on 14 October. In September tests, Pima cotton was more susceptible to leaf desiccation after applications of defoliants than upland cotton. Single applications of Ginstar or Dropp + Def gave good defoliation in September tests. In October, Pima cotton was effectively defoliated by chemical treatments but a single application of defoliants did not provide acceptable defoliation of upland cotton.
    • Arizona Upland Cotton Variety Testing Program

      Silvertooth, J.; Norton, R.; Clark, L.; Husman, S.; Cluff, R.; Stedman, S.; Thacker, G.; Grumbles, R.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Ten field experiments were conducted in many of the cotton growing areas of Arizona in 1994 for the purpose of evaluating Upland cotton varieties in terms of adaptability and performance. Seven 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.
    • Plant Growth Regulator Studies at the Safford Agricultural Center, 1994

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Methanol, Cytokin and PGR IV plant growth regulators were tested on long and short staple cotton on the Safford Agricultural Center in 1994. It was a follow up study on Methanol and Cytokin and a first time look at PGR IV.
    • 1994 Cottonseed Treatment Evaluations

      Norton, E. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Cottonseed was treated with several fungicide treatments in an effort to protect the seed and seedling from disease. Seed germination and vigor was evaluated in three Arizona locations; Maricopa, Marana, and Safford. Stand counts were taken on two separate dates after emergence at both Safford and Marana and once at Maricopa and percent emergence was calculated. Among the three locations two, Marana and Safford, showed significant differences among treatments. Treatment number 5 placed first at both locations where significant differences were found. The untreated control placed last in the ranking at both Marana and Safford for all dates of sampling.
    • Irrigation Frequency and Cotton Yield in Short-Season Cotton Systems

      Chu, Chang-chi; Henneberry, Thomas J.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      We tested the hypothesis that small frequent irrigations during the July cotton peak fruiting stage would result in better fruiting and higher cotton yields than the same amount of water applied less frequently. Over three years under a short - season production system, irrigation intervals of every 5-d with 42 mm of water applied at each irrigation increased cotton lint yield by 5-11 % compared to irrigation intervals of 10- and 15-d with 80 and 130 mm of water applied at each irrigation, respectively. The results show that small, frequent furrow irrigations during cotton fruiting are highly effective in reducing water deficit during critical growth stages and improved lint production in a short - season cultural system. Soil salt content in the top 15 cm of soil was not increased after three years of study.
    • Establishment of a Whitefly Resistance Documentation and Management Program in Arizona

      Dennehy, T. J.; Simmons, A.; Russell, J.; Akey, D.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Adult whiteflies were collected from six regions of Arizona and evaluated for susceptibility to fenpropathrin (Danitol®), acephate (Orthene®) and endosulfan (Thiodan®), and mixtures of fenpropathrin+acephate curl fenpropathrin+endosulfan. Strong indications of resistance to fenpropathrin, acephate and the fenpropathrin +acephate mixture were documented in some areas of the state. With all populations evaluated endosulfan was consistently the most toxic of the insecticides evaluated (singly) and was highly toxic in mixtures with fenpropathrin. Whitefly resistance to pyrethroid insecticides and especially mixtures of pyrethroid+organophosphate insecticides could have serious ramifications for the prevention of sticky cotton in Arizona. To combat further development of pyrethroid resistance cotton growers will need to reduce the number of pyrethroid treatments made per season.
    • Susceptibility of Arizona Populations of Lygus Bugs to Acephate (Orthene®) and Bifenthrin (Capture®)

      Dennehy, T. J.; Cramer, G. C.; DeBolt, J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Adult lygus bugs were collected from alfalfa fields in 6 different cotton producing areas of Arizona. The standardized, glass vial method was used to estimate susceptibility of the collected populations to the organophosphate insecticide, acephate (Orthene®), and the pyrethroid, bifenthrin (Capture®). Overall, lygus from throughout the state were very susceptible to bifenthrin. However, some populations were significantly less susceptible to bifenthrin than were others. Lygus populations with greater than 20% survivorship of 100 μg/ml vial bioassays with bifenthrin should be monitored to provide early warning of future problems with pyrethroid resistance. Resistance of lygus to acephate appeared to be widespread but not uniform in Arizona. While some populations had individuals surviving exposure to vial treatments of as high as 10,000 pg/ml acephate, other populations had no survivors of 1,000 pg/ml treatments. Lygus populations with survivors of 10,000 pg/ml vial bioassays should be considered highly resistant to acephate. Our findings illustrate that resistance levels are often unique from farm to farm, even within the same region. To preserve the long-term usefulness of acephate, where possible, cotton growers should consider using it no more than once or twice per season, on any given field.
    • Host Preference of Silverleaf Whitefly and Factors Associated with Feeding Site Preference

      Chu, C. C.; Hennberry, T. J.; Cohen, A. C.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Silverleaf whitefly (SLW), Bemisia argentifolii, Bellows and Perring, preferred cantaloupe to cotton, broccoli and lettuce in field and greenhouse studies. In the absence of cantaloupe, SLW preferred cotton to broccoli and lettuce. In the field, more eggs and fewer nymphs were found on broccoli than on cotton. Differences in the relative abundance of vascular bundles per unit of leaf area between the four plant species may partly account for differences in oviposition site selection. Vascular bundle volume/unit of leaf tissue volume was 50% greater in cantaloupe than in cotton and broccoli, which in turn were significantly greater than in lettuce. Most SLW on cotton leaves are found on underside leaf surfaces. Distances from top and underside leaf surfaces to the nearest vascular bundles in cotton leaves were 131 and 60 tun, respectively, in the present studies.
    • Community-wide Implementation of Samplin and Action Thresholds for Whiteflies in Cotton

      Diehl, J. W.; Ellsworth, P. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Sampling and decision-making plans for managing sweetpotato whiteflies were implemented within 8,000 acres of cotton within the Laveen-Tolleson area of central Arizona. On the average, thresholds utilized for the first whitefly treatment were lower than those recommended, but subsequent treatments were made at about recommended thresholds.
    • Silverleaf Whitefly: Honeydew Sugars and Relationship to Sticky Cotton

      Henneberry, T. J.; Hendrix, D. L.; Perkins, H. H.; Forlow Jech, L.; Burke, R. A.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ; USDA-ARS, SAA, Clemson, SC (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      In cotton plots heavily infested with silverleaf whitefly (SLW), Bemisia argentifolii Bellows and Perring, amounts (mg /g of lint) of sugar (fructose, glucose and sucrose combination) on lint from tagged bolls, varied but showed a general trend to increasing amounts with increasing time of exposure (days) for 52 days. Minicard lint stickiness ratings responded in a similar manner and all values were above acceptable thresholds. Lint from harvested mature open bolls that were exposed on trays suspended in the interior of SLW infested cotton plots showed increasing amounts of sugar and higher minicard ratings after 6 days. Amounts of sugar and minicard ratings were drastically reduced following rains of 1.5 inches.
    • Telone II® and Temik® Efficacy on Rootknot Nematodes in Cotton

      Husman, S.; McClure, M.; Lambeth, J.; Dennehy, T.; Deeter, B.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Field studies were conducted at four western Maricopa County commercial sites in 1994 to determine whether Temik 15G® would suppress rootknot nematode at low to moderate populations. Three of the experiments were on Upland D +PL 5415 with the fourth on Pima S-6. Sites were chosen based on pre- season sampling with individual field populations ranging from 0.005 (low) - 3.6 (high) rootknot nematode juveniles per cubic centimeter (cc) of soil volume. Each study consisted of four treatments with six replications. The following treatments were used at all test sites: (1) Untreated check, (2) 5 lbs. Temik 15G at planting, (3) 5 lbs. Temik 15G at planting, 15 lbs. Temik 15G sidedressed at pinhead square, (4) 5 gal. Telone 11® pre-plant. Sampling for thrips and lygus was conducted at all test sites to provide insight regarding yield effects resulting from control of insect versus those due to suppression of nematode. There were no significant yield differences between the untreated check and either Temik treatment. However, significant yield increases were measured with Telone versus all treatments at all locations. Insect pressures were minimal in all cases. Temik 15G did not suppress nematode damage at any population level.
    • Cotton Leaf Curl Virus, A Threat to Arizona Cotton?

      Nadeem, Athar; Xiong, Zhongguo; Nelson, Merritt; Silvertooth, Jeff; Department of Plant Pathology, University of Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A serious virus disease of cotton in Pakistan is distantly related to cotton leaf crumple in Arizona. It is much more destructive on cotton than leaf crumple, and has never been found in the western hemisphere. Cotton leaf crumple in Arizona causes only modestly damaging midseason infections, while leaf curl, has had a major impact on the crop in Pakistan. Modern transportation and the increasing movement of living plants in global trade has resulted in them recent introduction of a similar disease of another crop to the western hemisphere.
    • The Use of Fungi to Prevent Aflatoxin Contamination of Cottonseed in the Yuma Valley

      Cotty, P. J.; Silvertooth, Jeff; USDA, ARS, Southern Regional Research Center, New Orleans, LA (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A strain of Aspergillus flavus that does not produce aflatoxins was applied to soils planted with cotton at the Yuma Valley Agricultural Center in order to assess strain ability to competitively exclude aflatoxin producing strains during cotton boll infection and thereby prevent aflatoxin contamination of cottonseed. In both 1989 and 1990, the atoxigenic strain displaced other infecting strains during cotton boll development. Displacement was associated with significant reductions (75% to 82% in 1989, and 99% in 1990) in the quantity of aflatoxins contaminating the crop at maturity. Although frequency of infected locules differed between years, in both years displacement occurred without increases in the amount of developing boll infection. Currently, an Experimental Use Permit is being sought from the EPA for tests on commercial acreage
    • Effect of Soil and Foliar Applied Potassium on Pima and Upland Cotton at Two Arizona Locations

      Galadima, A.; Silvertooth, J. C.; Unruh, B. L.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Due to increasing emphasis and interest being placed on cotton (Gossypium spp.) fiber quality as well as yield benefits associated with potassium (K) fertilization, two studies were conducted in 1994. These studies with those before them were aimed at assessing the agronomic necessity of K fertilization in Arizona cotton production. The locations of the trials included Maricopa Agricultural Center (Casa Grande sandy loam) and Safford Agricultural Center (Pima clay loam). At the Safford location, both Upland (G. hirsutum L., var. DPL 90) and Pima (G. barbadense L., var. S-7) cotton were planted with treatments that included both soil and foliar K applications. The trials at Maricopa Agricultural Center included four foliar K applications over the growing season on Pima (G barbadense L., var. S-7) cotton. The results of the experiments at both locations indicated no lint yield responses to K fertilization by either Upland or Pima cotton.
    • Nitrogen Management BMPs Parker Valley Demonstration

      Watson, J.; Winans, S.; Sheedy, M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A nitrogen management demonstration was conducted in the Parker Valley in 1994. Grower nitrogen application practices were compared with nitrogen application recommendations based upon pre plant soil samples plus petiole nitrates and plant mapping data. The only significant difference in amounts applied occurred in May, with grower applied rates exceeding recommended rates. Grower rationale for the application was logical, however, it being dependent upon the uncertainty of irrigation timing in June.
    • Evaluation of Soil Conditioners and Water Treatments for Cotton Production Systems

      Unruh, B. L.; Silvertooth, J. C.; Sanchez, C. A.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Advanced technologies to produce synthetic polymers such as polyacrylamide (PAS, and polymaleic anhydride (PMA) have produced products which may be economically feasible alternatives to traditional treatments such as gypsum in the desert Southwest. In 1994 three field studies were initiated, two identical studies were located in the Yuma Valley and one at Paloma Ranch. At Yuma Valley the experiments included 0, 1, and 2 tons gypsum/acre, over which, various soil-applied treatments were made; including, a check, soluble PMA (Sper Sal™), and PAM (Hydro-Growth™). Upland cotton 'DPL 5461' was grown in both Yuma Valley studies. At Paloma Ranch, Upland 'DPL 5415' planted. Prior to planting, two gypsum applications were made at 0 and 2 tons/acre. Also included as treatments were various methods and rates of Sper Salt™. No differences among treatments were detected in either of these locations relative to crop yield. At Paloma Ranch there were some early-season differences in soil crusting among the various soil amendment treatments, however, these differences dissipated as the season progressed and did not result in lint yield differences.