• Cotton Irrigation Scheduling Trial on Pima and Upland Cotton Using AZSCHED, Safford Agricultural Center, 1995

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Irrigation scheduling is an important practice in cotton cultivation in the and southwest. AZSCHED irrigation scheduling software was used as a tool to schedule irrigation and then evaluate the soil water depletion levels over irrigation treatments with DP 90 and Pima S6. Lint yields were compared and irrigation costs were calculated for the various treatments. The highest yields and income levels came from applying irrigation when the soil depletion levels reached 40%.
    • Differential Tolerance of Cotton Cultivars to Prometryn

      Molin, William T.; Khan, Rehana A.; Pasquinelli, Michael; Galadima, Abraham; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      The tolerance of cotton cultivars to the herbicide prometryn was determined in greenhouse tests. Prometryn was applied preemergence from 0.3 to 12.0 lbs. a.i./A and postemergence from 1.2 to 12.0 lbs. a.i./A. Upland cultivars were very susceptible to injury from prometryn applied preemergence; whereas Pima S-6, Pima S-7, and Acala 1517-75 were tolerant. Postemergence treatments of prometryn applied two weeks after planting were less injurious to Upland cultivars than preemergence treatments, however, differential tolerance between, Pima and Upland cultivars was evident at the high rates of application.
    • Short Staple Regional Cotton 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)
      Forty one short staple varieties were grown in a replicated field trial on the Safford Agricultural Center. DP 5690 was the highest yielding variety with a yield of 1302 pounds of lint per acre with DP 90 in second place but with 100 pounds of lint less per acre. Seedcotton yields were essentially identical to 1994.
    • Effects of Silverleaf Whiteflies on Sticky Cotton and Cotton Yields in Arizona

      Henneberry, T. J.; Forlow Jech, Lynn; Silvertooth, Jeff; USDA, ARS, Western Cotton Research Laboratory, Phoenix, Arizona 85040 -8830 (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Silverleaf whitey, Bemisia argentifolii Bellows and Perring, adults and nymphs were significantly reduced season -long in cotton plots treated with fenpropathrin plus acephate on 3 occasions (15 July, 2 August and 29 August). Thermodetector sticky cotton ratings were significantly reduced in insecticide-treated plots compared with untreated plots. Heavy rains reduced cotton stickiness in all plots.
    • Short Staple Variety Trial, Greenlee County, 1995

      Clark, Lee J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Eight short staple cotton varieties including four New Mexico acalas and four California acalas were tested in the 1995 variety study. The highest yielding variety was 1517-95 with a lint yield of 1030 pounds per acre. The average yield was nearly 100 pounds per acre higher than the previous year. In addition to lint yields; percent lint, plant heights, height to node ratios and plant populations are shown. A lint yield comparison for 1991, 1993, 1994 and 1995 is included in this paper.
    • 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).
    • Comparison of Early Season and Mid-Season Applied Plant Growth Regulators on DPL 5415 Cotton

      Rethwisch, Michael D.; Rovey, Nathan; Heeringa, Nathan; Quist, Aron; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Several plant growth regulators were applied to DPL 5415 cotton to evaluate effectiveness on cotton lint yield. Growth regulators applied in small amounts over multiple applications early in the growing season reduced yields compared with the check while a single application applied at full-bloom slightly increased lint yields. High night time temperatures from late July into early September were detrimental for cotton production. Increased squaring of early season applications compared with the check may have resulted in reduced yields due to increased stress from temperatures and/or nutrient availability. Increased stress in the early treated (more fruit) plots may have had greater fruit abscission.
    • Reduced Tillage Systems for Airzona Cotton Growers

      Coates, Wayne E.; Thacker, Gary W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Four alternative tillage systems were compared to a conventional system at The University of Arizona Agricultural Centers in Marana and Yuma. The alternative tillage systems offer significant savings in energy, time, and cost. None of the reduced tillage systems were associated with a reduction in cotton yield.
    • 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.
    • 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.
    • Monitoring and Management of Whitefly Resistance to Insecticides in Arizona

      Dennehy, T. J.; Williams, Livy III; Russell, June S.; Li, Xiaohua; Wigert, Monika; Silvertooth, Jeff; Extension Arthropod Resistance Management Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Monitoring of whitefly resistance in the major cotton producing areas of Arizona confirmed the presence of an over 100 fold resistance to the mixture of Danitol® + Orthenem (fepropathrin + acephate). Strong evidence was found of cross-resistance affecting the other principle pyrethroid insecticides used to control whiteflies (Asana®, Capture® Karate®). Susceptibility to Ovasyn® varied widely in leaf -disk bioassays; lesser variation was observed in whitefly susceptibility to endosulfan. A provisional resistance management strategy (IRM) for Arizona whiteflies was formulated and evaluated in a 200 acre field trial in 1995. A key element of the strategy was diversifying as much as possible the insecticides used against whiteflies. Contrasts of this (rotation) strategy with a more conventional (less diverse) regime showed that rotation slowed but did not prevent resistance from developing. By seasons end both the IRM and conventional plots had very high and comparable levels of resistance to Danitol® + Ortliene®. This large field trial illustrated clearly the seriousness of the whitefly resistance problems faced in Arizona. It showed that whitefly populations cannot be managed effectively solely with the products currently registered for this purpose in Arizona. The large shift to lower susceptibility took place with as few as 3 insecticide treatments. In concert, our field art laboratory results indicated unequivocally that Arizona growers will be forced by resistance to greatly reduce reliance on pyrethroid insecticides in the future. This underscores the urgency for obtaining approval of novel new insecticides for whitefly control and for deploying new products within the framework of a resistance management strategy that limits their use.
    • Low Desert Upland Cotton Advanced Strains Testing Program, 1995

      Husman, S. H.; Jeck, L. E.; Metzler, F.; Wegener, R.; Killian, K.; Stephens, L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Twenty one Upland cotton advanced strains varieties which are not commercially available were evaluated in replicated field studies in 1995 on two farm sites in Queen Creek, Arizona and Buckeye, Arizona representing seven seed companies. Twenty four advanced strains representing eight seed companies were evaluated on a commercial site in Gila Bend, Arizona. Participating seed companies submitted three advanced strain entries, plus a commercially available check of their choice at each site. The Gila Bend site represented strains of a more indeterminate nature for a full season production approach, while the sites at Buckeye and Queen Creek consisted of more determinate entry characteristics to represent a reduced season production approach. The highest lint yields were obtained from Germains 9230 (1756 lb./a), Delta and Pine Land Co. 5517 (1116 lb./a), and Delta and Pine Land Co. 9057 (1578 lb./a) at Queen Creek, Buckeye, and Gila Bend respectively.
    • How the Quick Hitch Guidance Systems Work and Their Practical Applications

      Thacker, Gary W.; Coates, Wayne E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      This article explains the operation of the two types of quick hitch guidance systems on the market. Techniques for farming with precision guidance are offered.
    • 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.
    • Effect of Norflurazon (Zorial Rapid 80®) Mixed with Pendimethalin (Prowl®) and Prometryn (Caparol®) on Cotton Stand Establishment and Yield

      McCloskey, William B.; Dixon, Gary L.; Silvertooth, Jeff; Department of Plant Sciences, University of Arizona, Tucson, Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      The effect on cotton stand establishment and seed cotton yield of various rates of norflurazon applied in combination with pendimethalin or both pendimethalin and prometryn was determined in field studies conducted at the Maricopa Agricultural Center in 1994 and 1995 in a sandy loam soil. Cotton stand counts were highest when only pendimethalin was applied or when no herbicide was used. Tank mixing prometryn with pendimethalin did not significantly reduce plant populations. Tank mixing increasing amounts of norflurazon with pendimethalin resulted in decreasing plant populations in both the wet and the dry plant experiments. Tank mixing increasing rates of norflurazon with both pendimethalin and prometryn caused a similar decline in plant populations in both the wet and the dry plant experiments. The symptoms of dying cotton seedlings and the stand count data indicated that notflurazon was the component of the tank mixtures that caused seedling mortality. The effect of the herbicide treatments on seed cotton yields was much less than on stand counts, but the same trends discussed above were evident. However, at the label rate for norflurazon in coarse textured soils, 0.5 lb a. i./A, seed cotton yields were not significantly reduced. The smaller effect of the herbicide treatments on seed cotton yields was due to the bush type nature of DPL 5415 and increased growth of surviving plants when plant populations were reduced. The data indicates that yield losses were not significant unless plant populations were reduced below about 20,000 to 25,000 plants /A.
    • 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.
    • 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.
    • 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.
    • Arizona Upland Cotton Variety Testing Program

      Silvertooth, J.; Norton, R.; Clark, L.; Husman, S.; Cluff, R.; Stedman, S.; Thacker, G.; Knowles, T.; Winans, W.; Grumbles, R.; et al. (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Eleven field experiments were conducted in many of the cotton growing areas of Arizona in 1995 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 150 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. The 1995 season offered some extremes in terms of weather conditions, with very cold spring temperatures, followed by very hot conditions in July and August. Variety performance under these extremes offers an opportunity for review and comparison with regard to adaptability. 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.
    • Chemical Control Studies of Silverleaf Whitefly Control

      Chu, C. C.; Henneberry, T. J.; Silvertooth, Jeff; USDA, ARS, Western Cotton Research Laboratory, Phoenix, Arizona 85040 -8830 (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Chemical control studies for silverleaf whitefly, Bemisia argentifolii Bellows and Perring, control on cotton showed that fenpropathrin-acephate, fenpropathrin-endosulfan, and endosulfan-bifenthrin mixtures gave adequate control and increased cotton yields were obtained as compared within untreated cottons. Pyriproxyfen, applied biweekly or alternated with fenpropathrin-acephate, Nicotiana, and a fenpropathrin-mycotrol mixture also gave effective control.