• Potassium Fertilization of Pima and Upland Cotton at Three Arizona Locations

      Galadima, A.; Silvertooth, J. C.; Norton, E. R.; Husman, S. H.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Three field trials were conducted in Arizona in 1995 at three locations (Safford, Maricopa and Buckeye) to evaluate yield benefits associated with potassium (K) fertilization. The 1995 and previous years studies were aimed at assessing the agronomic necessity of K fertilization in Arizona cotton (Gossvpium spp.) production. At the Safford Agriculture center (Pima clay loam), both Upland (G hirsutum L., var. DPL 90) and Pima (G. barbadense L., var. S-7) cotton included treatments of both soil and foliar K applications. The trial at Maricopa Agricultural Center (Casa Grande sandy loam) included four foliar K applications over the growing season on Pima (G barbadense L., var. S-7) cotton. The third trial was at the Buckeye location (Superstition silty loam) where a single foliar application over split plots preceded by soil application on Pima (G. barbadense L, var. S-7) cotton was undertaken. The results of the experiments at the Safford and Maricopa locations indicated no lint yield responses to K fertilization by either Upland or Pima cotton; however, at the Buckeye location, the result indicated a significant difference between the means of the soil-only and the soil-plus-foliar treatments. There were however no significant differences among soil-only treatments as well as the soil-plus-foliar treated plots when compared to their respective controls.
    • Research Note on Effects of Diurnal Temperature Extremes on Cotton Yields at the University of Arizona Maricopa Agricultural Center

      Warren, D. C.; Rauschkolb, R. S.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      An examination of the weather record for the University of Arizona Maricopa Agricultural Center revealed that short staple cotton yields were negatively affected by cool summers. Cool summers are here defined as June through August months with many days having cooler than average max temperatures for those months. No correlation to yield was found for nighttime temperature; nor was there a detectable effect of higher than average temperature affecting yields.
    • Evaluation of Soil Conditioners and Water Treatments for Cotton Production Systems

      Silvertooth, J. C.; Sanchez, C. A.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Advanced technologies to produce synthetic polymers such as polyacrylamide (PAM, and polymaleic anhydride (PMA) have produced products which may be economically feasible alternatives to traditional treatments such as gypsum in the desert Southwest. In 1995 a single field study was conducted at Paloma Ranch, west of Gila Bend in Maricopa County Arizona Upland Nucoton 35, DPL' was dry planted and watered -up on 10 and 11 April. Treatments consisted of various rates and times of applications of Sper Sal™, which included a check (no Sper Sal), 1 and 2 qts. /acre with the water-up irrigation; 1 and 2 qts./acre with a mid - season irrigation; and 1 qt. /acre mid-season following 1 or 2 qts./acre with the water -up irrigation. No differences among treatments were detected among any treatments in terms of plant growth and development or final lint yields. There were no early-season differences in soil crusting among the various soil amendment treatments in 1995, as opposed to 1994 when a severe rain occurred immediately following planting.
    • Magnitude and Strain Composition of Aspergillus flavus Soil Surface Populations in Yuma County Commerical Fields

      Nelson, M. R.; Bigelow, D. M.; Orum, T. V.; Howell, D. R.; Cotty, P. J.; Silvertooth, Jeff; Department of Plant Pathology, University of Arizona, Tucson; Cooperative Extension Service, University of Arizona; Southern Regional Research Center, USDA, ARS (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Aflatoxin contamination of cottonseed occurs when cotton bolls are infected by certain strains of the fungus Aspergillus flavus. The risk of aflatoxin contamination in a field is partially dependent on both the quantity of A. flavus and the toxigenicity of A. flavus strains in that field. A. flavus can be easily divided into two major subdivisions known as strain S and strain L. Strain S isolates consistently produce large amounts of aflatoxin and, therefore, the percentage of strain S isolates in the population (percent S) is one indication of the aflatoxin producing potential of the population. Strain S isolates were found in every commercial field sampled at every sampling date in Yuma County, but percent S varied greatly among fields from 4% to 93 %. Significant differences among fields located near each other suggest that locally important, but not yet identified, variables such as crop rotation histories or soil type are affecting A. flavus population magnitude and composition.
    • Telone II® and Temik® Efficacy on Root-knot Nematodes in Cotton

      Husman, S.; McClure, M.; Deeter, B.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      A field plot in western Maricopa county was established in 1995 to determine the ability of Temik® brand aldicarb pesticide to suppress root-knot nematode when Temik 15G was applied as a seedling side-dress and moved into the root zone by irrigation. Telone II® was used for comparative purposes and Gaucho-treated seed, following a preplant application of Telone, was included to determine if additional benefits could be realized by systemic control of insects during early stages of plant growth. Plans to include foliar applications of Orthene® were abandon when early season thrips populations failed to develop. Temik 15G, applied as a side-dress at 10 lbs. did not suppress nematodes or increase lint yield Telone, alone and in combination with Gaucho -treated seed, reduced nematode populations and increased lint yield, but differences between the two Telone treatments were not significant. Insect pressure was not a contributing factor. Greenhouse studies showed that both timing of the application and its placement in the row will be of critical importance when Temik is applied for nematode control in furrow irrigated cotton.
    • Pima Variety Test, Marana, 1995

      Thacker, G.; Norton, R.; Silvertooth, J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Four Pima varieties were grown in a replicated trail on the Evco Farm in Marana. There were no significant differences in lint yield.
    • How to Mechanically Remove Weeds from the Row

      Thacker, Gary W.; Coates, Wayne E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      This article offers practical advice on in-row weeding techniques and tooling setups.
    • 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), 1996-03)
      A single field experiment was conducted in 1995 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 to node ratios (HNRs) according to established baselines. Scheduled and feedback PIX applications were made for a total of 1.0 pt./acre over two applications, with the scheduled treatments-taking place earlier in the fruiting cycle (early and peak bloom). Feedback PIX treatments began with a single 0.5 pt. /acre application near peak bloom (approx. 2200 heat units after planting (HUAP), 86/55 °F threshold) and followed with a second 0.5 pt. /acre application in late bloom. Scheduled applications of fertilizer N totaled 200 lbs. N/acre from three applications and feedback N treatments received a total of 100 lbs. N/acre from two applications. Treatments consisted of all combinations of scheduled or feedback applications of both N and FIX. The highest lint yields were from a treatment receiving feedback N and FIX, 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 1995 are consistent with 1993 and 1994 results from the same study.
    • Pima Cotton Regional Variety Trial, Safford Agricultural Center, 1995

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Eighteen 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 1995 was OA 312 (Conquistador) with a yield of 937 pounds of lint per acre. It was followed by OA 304 the high yielding variety from the year before and three other Olvey varieties and Phytogen 57. The average yield from this trial was nearly 100 pounds per acre higher than the previous trial Yield and other agronomic data as well as fiber quality data are contained in this paper.
    • Distribution and Genetic Variability of Whitefly-Transmitted Geminiviruses of Cotton

      Brown, J. K.; Silvertooth, Jeff; Department of Plant Sciences, University of Arizona, Tucson, Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Whitefly-transmitted geminiviruses (subgroup III, Geminiviridae) are emerging viral pathogens of cotton, worldwide. Virtually nothing is known about the genetic variability, biological characteristics, or the molecular epidemiology of these new virus pathogens of cotton. The core region (550bp) of the geminiviral coat protein gene was examined as a potentially informative molecular marker by which to identify and track the global distribution of WFT geminiviruses of cotton. This is an essential step toward assessing the risks that emerging viruses pose to cotton production efforts. Preliminary analyses of geminivirus isolates from North America, Central America and the Caribbean Basin, and Sudan indicate that the core region of the coat protein gene permits predictions about relationships between virus isolates from cotton, based on subgeographical and major geographical origins, and has potential for distinguishing between geminiviral quasi-species and virus strains, thereof Through these efforts, a database of geminivirus coat protein gene sequences has been established to permit identification of additional isolates from cotton, and to facilitate the tracking of WFT geminiviruses for molecular epidemiological and subsequent risk assessment objectives. Using the latter information, it will become possible to identify the most important geminiviruses against which disease resistance efforts should be directed. Further, the availability of a broad suite of cotton geminivirus isolates from both Eastern and Western Hemispheres will permit assessment of cotton germplasm and/or genetically engineered lines for virus-specific and/or broad spectrum disease resistance for the first time.
    • Defoliation Tests with Ginstar at the Maricopa Agricultural Center in 1995

      Nelson, J. M.; Hart, G. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Defoliation tests were conducted on upland cotton at the Maricopa Agricultural Center to evaluate rates of Ginstar and tank mixes of Ginstar with Def, Prep, and spray adjuvants. In September when temperatures were high, good defoliation was obtained 14 days after treatment using Ginstar at 0.094 lb. a. i./acre. As temperatures cooled in early October, a higher rate of Ginstar was necessary to achieve defoliation. Under very cool temperatures in late October and early November, the tank mix of Ginstar + Def generally improved defoliation over Ginstar used alone. Several adjuvants appeared to improve the effectiveness of Ginstar when temperatures were cool.
    • Effects of Combinations of Accelerate and Other Defoliants on Defoliation of Upland Cotton

      Nelson, J. M.; Silvertooth, Jeff; Maricopa Agricultural Center (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Field studies were conducted on upland cotton at the Maricopa Agricultural Center to evaluate the effectiveness of Accelerate when used in combination with other defoliants. In a September test, good defoliation was obtained in seven days using Ginstar or Dropp + Def + Accelerate and in 14 days using Accelerate + Prep. In October, under cooler conditions, no treatment provided acceptable defoliation in 14 days. In both tests, Ginstar used alone resulted in higher leaf drop percentages than Ginstar + Accelerate.
    • Plant Growth Regulator/Foliar Nutrient Studies at the Safford Agricultural Center, 1995

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Methanol, Cytokin, Cytoplex, PGR IV and Foli-Zyme plant growth regulators were tested on long and short staple cotton on the Safford Agricultural Center in 1995. It was a follow up study on Methanol, Cytokin and PGR IV and a first time look at Cytoplex and Foli-Zyme. Trends toward increased lint yield were seen with Cytokin and Cytoplex with the other treatments yielding near or below the untreated check Some increase in maturity was seen on the short staple plots by all of the treatments. Some differences in HVI data were also observed.
    • Fenoxycarb, Pymetrozine (C G A-215944), and Fenpropathrin/Acephate: Rotations for Silverleaf Whitefly Control in Upland Cotton in Central America

      Akey, D. H.; Henneberry, T. J.; Silvertooth, Jeff; USDA, ARS, Western Cotton Research Laboratory, 4135 East Broadway, Phoenix, Arizona 85040 -8830 (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Trials (0.01 ac plots) with fenoxycarb ( Fenoxycarb 40 W P, 0.0621b. ai /ac), pymetrozine (CGA 215944, Fulfill™ 50 W P, 0.094 lb. ai/ac), pymetrozine /fenoxycarb, (SterlingTM ), and fenpropathrin (DanitolTM 2.4 E C, 0.20 lb. or 0.10 lb. ai/ac) /acephate (OrtheneTM 90 S, 0.5 or 0.25 lb. ai /ac) were made against silverleaf whitefly, Bemisiq grgentifolii Bellows and Perring, at UA, Maricopa Agric. Ctr. Six applications (plus adjuvant Kinetic) were applied on 9 treatments. Ten treatments (embedded control included) were in a double tier complete random block design and there was I adjacent, 1.5 ac control block (treatment 11). Eggs and large nymphs were sampled weekly post application to determine efficacy; reported as % reduction from block control. Rotation schemes were: 1) 3 pymetrozine /fenoxycarb, then 3 fenpropathrin/acephate applications, 2) 3 pymetrozine 2 /3rate /fenoxycarb full rate, then 3 fenpropathrin /acephate applications, 3) fenoxycarb 6 applications, 4) pymetrozine 6 applications, 5) 3 fenpropathrin /acephate, then 3 pymetrozine /fenoxycarb applications, 6) 3 fenpropathrin /acephate, then 3 pymetrozine /fenoxycarb, 7) fenpropathrin /acephate at full, l/2, full, then 3-1/2 rate applications, 8) 2 pymetrozine /fenoxycarb, 2 fenpropathrin /acephate, 1 pymetrozine /fenoxycarb, and 1 last fenpropathrin /acephate application, 9) 2 fenpropathrin /acephate, 2 pymetrozine /fenoxycarb, 1fenpropathrin/acephate, and 1 last pymetrozine /fenoxycarb application, 10) embedded control, and 11) block control. Egg % reductions for season means ranged from 93-99% for combinations and rotations of them. Last % season analyses showed reductions from 95-99 %. Pymetrozine had a 98% reduction andfenpropathrin /acephate had 98 % egg reduction. Nymphal reduction for season means ranged from 80-95% for combinations and rotations of them. Last % season analyses, showed % reductions from 91-98 %. Pymetrozine had 92% reduction and fenpropathrin /acephate had 92% reduction of nymphs (season). These studies showed that pymetrozine, pymetrozine /fenoxycarb, fenpropathrin/acephate combinations and rotations provided excellent control of silverleaf whitefly immatures.
    • The 1996 Arizona Cotton Advisory Program

      Brown, P.; Rusell, B.; Silvertooth, J.; Ellsworth, P.; Stedman, S.; Thacker, G.; Husman, S.; Cluff, R.; Howell, D.; Winans, S.; et al. (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Arizona Cooperative Extension generates and distributes weather -based Planting Date and Cotton Development Advisories for 14 cotton production areas (Marana, Laveen, Paloma, Litchfield Pk., Pinal Co., Parker, Mohave Valley, Queen Creek, Safford, Yuma Valley, Aguila, Cochise Co., Greenlee Co. and Harquahala). Planting Date Advisories are distributed from mid -February through the end of April and stress 1) planting cotton varieties according to heat unit accumulations rather than calendar date and 2) the importance of soil temperature to good germination. Cotton Development Advisories are distributed from early May through mid - September and provide updates on crop development, insects, weather and agronomy. The Cotton Advisory Program will continue in 1996 and growers may obtain advisories by mail or fax from the local county extension office, and by computer from AZMET or the University of Arizona College of Agriculture World Wide Web Page. Major program changes planned for 1996 include 1) adjusting the Crop Development Advisories to reflect the revised legal first planting dates in low elevation production areas and 2) the addition of an advisory for Harquahala.
    • 1995 Weather Conditions

      Brown, P.; Russell, B.; Machibya, T.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      The 1995 cotton season proved to be one of the most challenging in marry years. Cold, dry spring weather delayed planting and forced many growers to replant a significant portion of their crop. The late crop then ran into extreme summer heat in July and August and very high August humidity. Daytime temperatures in excess of 120°F were reported in the low deserts in July and many locations reported extended periods with daytime temperatures above 1107. Poor fruit retention was a common grower observation as the summer heat continued The saving grace for 1995 proved to be warm and dry fall weather which assisted late season development and harvest operations.
    • Development of a Yield Projection Technique for Arizona Cotton

      Norton, E. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      A series of boll measurements were taken at several locations across the state in 1995 in an attempt to develop a yield prediction model. Measurements were taken out of two strip plot variety trials at the University of Arizona Maricopa Agricultural Center and in the Coolidge area, and also out of two commercial fields in Buckeye and Paloma Ranch over a period of approximately 2 months from peak bloom through cut-out. Data analysis revealed a best fit model that included seedcotton yield as a function of boll count, boll size, boll diameter, and heat units accumulated after planting (HUAP). A series of open boll counts were also taken from over 120 experimental units across the state within one week of harvest. The data revealed strongest relationships between final open boll counts and yield.
    • Nitrogen Management Experiments for Upland and Pima Cotton, 1995

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Three field experiments were conducted in Arizona in 1995 at three locations (Maricopa, Marana, and Safford). The Maricopa and Safford experiments have been conducted for seven consecutive seasons, the Marana site was initiated in 1994. 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. At each location, treatments varied from a conservative to a more aggressive approach of N management. Results at each location 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 higher, more aggressive, N application regimes did not benefit yields at any location. The effects of N fertility levels have also been consistently evident in crop maturity and its relationship to lint yields.
    • Short Staple Variety Demonstrations, Graham County, 1995

      Clark, Lee J.; Cluff, Ronald E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Two on farm, replicated short staple variety demonstrations were established in 1995. Twelve varieties were evaluated on the Carpenter farm in Solomon and on the Colvin farm in Eden. Several new varieties were planted in both studies, including 2 varieties from Hartz Seed and a new Stoneville entry. Delta Pine 5690 and SureGrow 501 were the highest yielding varieties with yields of 1018 and 1446 pounds of lint per acre at the Solomon and Eden locations, respectively.
    • Short Staple Cotton Advanced Strains Trial, Safford Agricultural Center, 1995

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Sixteen short staple advanced strains/varieties were grown in a replicated field on the Safford Agricultural Center in 1995. These included entries from ChemBred, Delta Pine, Sure-Grow, Olvey and Associates, McDaniels, NMSU and Australia. The Australian materials produced quite well with three of the entries placing in the top four with respect to lint yield. The highest yielding cultivar being an Australian entry, A83203-183, with a yield of 1508.5 pounds of lint per acre. In addition to yield data, this report includes many agronomic parameters including seedling vigor index, height to node ratio, and boll size. HVI analyses are also included in the report.