• Response of Cotton to Precision-Guided Cultivation and DSMA in a Dense Stand of Purple Nutsedge

      Thacker, Gary W.; McCloskey, William B.; Silvertooth, Jeff; UA Cooperative Extension, Pima County, Tucson, Arizona; Department of Plant Sciences, University of Arizona, Tucson, Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Close cultivation (within 1.5 inches of the cotton drill row) accomplished with an electro-hydraulic machine guidance system and an early season application of the herbicide DSMA were evaluated for purple nutsedge suppression in cotton. There were no significant differences in the cotton plant mapping data collected mid - season except that there was significantly less boll retention on the second fruiting branch in the precision cultivator treatments that may have been caused by root pruning during the second precision cultivation that could have shocked the cotton. There were significant differences in seed cotton yield with the precision cultivator treatments yielding more than the standard cultivator treatments. There was an opposing yield trend with the use of DSMA; DSMA tending to be beneficial with the precision cultivator and detrimental with the standard cultivator. We cannot explain this opposing trend. We regard our results as preliminary until we gain more experience with precision-guided cultivators in dense stands of nutsedge.
    • 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.
    • Row Spacing Studies, Safford Agricultural Center, 1994 and 1995

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Four varieties (or variety types) were tested over three row spacings in the two years reported in this study. Two barbadense varieties, S6 and S7 or OA 312, and two hirsutum varieties, DP 90 and a NM acala were planted in 30 inch, 36 inch and 40 inch row spacing environments. Optimal row spacing varied by variety over the two years but averaged over the two years, the 36 inch spacing provided the highest yields for all varieties except for the NM acatas.
    • 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.
    • 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.
    • Comparison of Various Plant Growth Regulators on Pima S-7 Cotton Yields

      Rethwisch, Michael D.; Hurtado, Greg; Hurtado, Rosario; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      All plant growth regulators and nutritional products applied to Pima S-7 cotton during bloom economically increased lint yields, with increases ranging from 80 - 261 lbs. /acre. Greatest increase was noted with Boll-Set Plus, a product that contains raised levels of calcium and zinc. Cytokin and Boll -Set Plus significantly increased yields at one location. A lint yield increase of approximately 40 lbs/acre was noted when Tech-Flo Alpha was added to Cytokin. A single application of Foliar Triggrr resulted in equal yields as two applications of the Cytokin plus Tech-Flo Alpha.
    • Defoliation of Pima and Upland Cotton at the Safford Agricultural Center, 1995

      Clark, L. J.; Carpenter, E. W.; Odom, P. N.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Twelve defoliation treatments were applied to Pima and upland cotton to compare the treatment effects on percent defoliation of the plants, percent first pick values, percent gin trash and any effects they might have on fiber qualities. All of the treatments were beneficial compared to the untreated check, but differences between treatments were small.
    • Evaluation of Irrigation Termination Management on Yield of Upland Cotton, 1995

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      A single field study was conducted in 1995 at the Maricopa Agricultural Center (1100 ft. elevation) to evaluate the effects of three dates of irrigation termination on yield a common Upland cotton variety (DPL 5415). Planting date was 3 April (469 HU /Jan 1 86/55° F thresholds). Following difficult establishment, crop vigor was generally low all season, with a relatively strong level of fruit retention. Three dates of irrigation termination an -1T3) were imposed based upon crop development into cut -out, with IT1 (21 August) set such that bolls set at the end of the first fruiting cycle would not be water stressed and could be fully matured. The third termination (IT3) date was 22 September, which was staged so that soil moisture would be sufficient for development of bolls set up through the first week of September. The second irrigation termination (IT2, 1 September) was intermediate to IT1 and IT3. Lint yield results revealed a 139 lb. lint/acre difference between IT1 and IT3, which was statistically significant (P < 0.05).
    • 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.
    • Cotton Defoliation Evaluations, 1995

      Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      A single field experiment was conducted near Coolidge, AZ in 1995 to evaluate the effectiveness of a number of defoliation treatments on Upland cotton (var. DPL 5415). All treatments consisted of materials commercially available in Arizona, and each showed promise in terms of overall effectiveness. Results do provide reinforcement for current defoliation guidelines for Arizona which recommend using low rates (relative to the label ranges) under warm weather conditions, and increasing rates as temperatures cool.
    • Cotton Growth and Development Patterns

      Silvertooth, J. C.; Norton, E. R.; Brown, P. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Summaries of cotton crop phenology, as a function of heat units (HU, 86/55°F limits) have been developed across a wide range of production conditions in Arizona. Basic phenological events such as the occurrence of pinhead squares, squares susceptible to pink bollworm, and first bloom are described in terms of HU accumulations since planting (HUAP). Fruit retention guidelines and height: node ratios, which measure a crop's vegetative /reproductive balance, are developed as a function of HUAP. Similarly, the rate of canopy closure is described in terms of HUAP. The use of the number of nodes above the top white bloom to the terminal (NAWB) is developed as a measure of a crops progression towards cut-out. Also, the expected ranges of HU's accumulated since planting that are required to accomplish crop cut-out are shown for Upland and Pima cotton.
    • 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.
    • Upland Advance Strains Cotton Variety Test at the Maricopa Agricultural Center, 1995

      Hart, G. L.; Nelson, J. M.; Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Eighteen upland cotton advance strains were grown in a replicated trial at the Maricopa Agricultural Center. Lint yield, boll size, lint percent, plant population, plant height and fiber property are presented in this report.
    • 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.
    • Upland Regional Cotton Variety Test at the Maricopa Agricultural Center, 1995

      Hart, G.; Nelson, J. M.; Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Twenty-seven upland cotton varieties were grown in a replicated test at the Maricopa Agricultural Center as part of the National Cotton Variety Testing Program. Lint yield, boll size, lint percent, plant population, plant height and fiber property data are presented in this report.
    • 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.; Grumbles, R.; Knowles, T.; Dunn, D.; Schneider, M.; Silvertooth, Jeff (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.
    • 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.
    • 1995 Seed Treatment Evaluations

      Norton, E. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      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 two Arizona locations; Maricopa and Marana. Stand counts were taken on two separate dates after emergence at both Maricopa and Marana and percent emergence was calculated. Significant differences in percent emergence due to treatment were observed in both sample dates at Marana. Results at Maricopa were not statistically significant but similar trends to those at Marana were observed with treatment number 6 (no treatment) having the lowest percent emergence and treatment number 2 (combination of Nu-Flow ND and Apron TL) having the highest emergence.
    • Assessing the Impact of Irrigation Management Strategies on Yield and Nitrate Leaching in Upland Cotton Production

      Martin, E. C.; Pegelow, E. J.; Watson, J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Although the cost for water is one of the largest expenditures in a grower's budget, many growers still over -irrigate their fields to assure that there will be no yield losses. Although these over -irrigations usually do not cause any negative effect to the crop, they can cause the loss of available nitrogen to the plant and the potential of nitrate contamination of groundwater resources. To assess what impact over-irrigation may have on yield and the potential for groundwater contamination, a drainage lysimeter study was initiated at the Maricopa Agricultural Center, Maricopa Arizona. Drainage lysimeters are large steel boxes with the tops open. In this study, three lysimeters were installed. The lysimeters were 80" wide (two row widths), five feet long, and six feet deep. They were placed 18 inches below the soil surface and filled with soil as to best represent the soil in its natural condition. On April 10, cotton was dry planted and watered up. Throughout the season, water samples were taken from the lysimeters and from suction lysimeters placed in the field. Nitrogen applications were made according to field conditions and weekly petiole sampling. Irrigations were made according to field conditions and using the AZSCHED irrigation scheduling program. Treatment one was irrigated according to the schedule and amount recommended by AZSCHED. In treatment two, the timing was the same as treatment one, but the amount applied was 0.25 times more. Treatment three was also irrigated at the same time but with 0.5 times more water. Yield samples were taken at the end of the season and showed no significant differences between treatments, with yields averaging about 1100 lbs /acre of lint. The drainage amounts ranged from 4" in treatment three to 1.5 inches in treatment one. The corresponding nitrate -N losses were 33 lbs/acre for treatment three and 20 lbs/acre for treatment one. Monitoring will continue over the winter to assess the impact of winter rainfall.