• 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.
    • Nitrogen Management Experiments for Upland and Pima Cotton, 1994

      Silvertooth, J. C.; Norton, E. R.; Unruh, B. L.; Navarro, J. A.; Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Three field experiments were conducted in Arizona in 1994 at three locations ( Maricopa, Marana, and Safford). The Maricopa and Safford experiments have been conducted for six consecutive seasons, with consistent plot locations; 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. 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 effects of N fertility levels have been consistently evident in crop maturity and its relationship to lint yields.
    • Pima Cotton Genetics

      Percy, R. G.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A short season feasibility study, using early maturing Pinta genotypes was conducted for a second season. Four early maturing genotypes, a short season check (P62) and a full season check variety (PS-7) were evaluated in replicated tests under short season and full season regimes. In both 1993 and 1994, most genotypes reached cutout around August 4, with 2759 accumulated heat units. All genotypes were earlier maturing than PS-7, as indicated by plant growth measurements and by sequential harvests. In 1994, the four early maturing experimental genotypes produced yields equal to or slightly better than the longer season cultivar PS-7. No differences in yield occurred between the short season and standard practice management systems in either year. A fiber improvement project was initiated in 1989 with the primary goals of increasing the fiber length and strength potential of Pima cotton. In 1989 the early maturing, short statured Pima strain P62 was crossed to Giza 45 and Giza 70 to transfer the fiber strength of those varieties into a heat tolerant, earlier maturing, productive Pima background. Likewise, P62 was crossed to the Sea Island cultivar St. Vincent V-135 with the objective of transferring the latter cultivar's long fiber length into an agronomic Pima background. Two resulting lines, one possessing high fiber strength and the other possessing high fiber length are planned for release in 1995-96.
    • Pima Cotton Improvement

      Moser, H. S.; Percy, R. G.; Ray, I. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      The objective of this study was to evaluate the performance of five experimental lines (P73, P75, P76, P80, and P81) with two commercial varieties ('Pima S-6' and 'Pima S-79 of Pima cotton. All seven strains were grown in replicated strip tests at four locations across the Pima belt in 1994. While none of the experimental lines produced significantly more lint than the best Pima variety at any site, some of them possess traits that are valuable to Pima cotton breeders. P73 has long and strong fiber. P76 is a high yielding, early maturing line that produces long and strong fiber. P80's lint yields are similar to Pima S-7, but it is significantly earlier.
    • Pima Cotton Regional Variety Trial, Safford Agricultural Center, 1994

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Ten long staple varieties (including two Pima experimental lines) were tested in a replicated small plot trial on the Safford Agricultural Center in Graham county at an elevation of 2950 feet. Even though the total number of heat units received during the season was nearly as high as the previous year, the average yield was nearly 300 pounds per acre lower. Olvey and Associates OA 304 was the highest yielding variety with a yield of 776 pounds per acre of lint and only two varieties broke the bale and a half mark. Yield and other agronomic data as well as fiber quality data are contained in this paper.
    • Pima Regional Variety Test; Maricopa Agricultural Center, 1994

      Hart, G. L.; Nelson, J. M.; Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Nine Pima varieties and experimental strains were grown in a replicated trial at the Maricopa Agricultural Center. Lint yield, boll size, lint percent, plant population and fiber property data are presented in this report.
    • 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.
    • Plant Population Evaluation for Upland Cotton

      Norton, E. R.; Silvertooth, J. C.; Stedman, S. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Plant population management is an important aspect of cotton production. Recommendations for optimum plant densities range from 25,000 - 45,000 plants per acre (ppa). A study was conducted in Pinal county in 1994 to evaluate the recommendations already given. Plant densities for this study ranged from approximately 18,000 - 65,000. Yields increased with populations of 18,000, 28,000, and 39,000 ppa. For populations of 43,000 and 65,000 ppa a corresponding decrease in yield from 39,000 ppa was observed. This study serves to reconfirm the recommendations for optimum plant densities.
    • Practical Considerations of Precision Guidance and Weed Control in Cotton

      Thacker, Gary W.; Coates, Wayne E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      This paper offers practical advice to growers interested in precision guidance technologies. Various types of guidance systems are described, along with their potential applications and benefits in a farming operation. Also discussed are some of the techniques which can be employed with precision guidance, including mechanical removal of weeds in the row, improved nutsedge control, and precision herbicide applications.
    • Precision Guidance Techniques to Reduce Weed Competition and Production Costs in Cotton

      Thacker, Gary W.; Coates, Wayne E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      The objective of this project is to evaluate the benefits of precision guidance systems as a means of using tillage to kill weeds, and to confine herbicide applications to narrow bands. In cotton, a precision guided close cultivation with a directed spray of MSMA significantly reduced a purple nutsedge stand early on. However this reduction was not significant by the end of the season. For controlling woolly morningglory, the use of a precision guided cultivator equipped with in -row weeding devices resulted in much lower numbers of morningglory weeds, although the differences were not significant at the 95% confidence level. The guidance system kept the implement precisely aligned to the drill rows at a higher speed than was possible with the cooperator's non - precision cultivator. This higher productivity more than offsets the cost of the guidance system and the in-row weeding devices.
    • Short Staple Cotton Advanced Strains Trial, Safford Agricultural Center, 1994

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Twenty six short staple advanced strains/varieties were grown in a replicated field trial on the Safford Agricultural Center. SureGrow SGX247 was the highest yielding cultivar in the trial with a lint yield of 1628 pounds per acre. The exciting feature of this trial is that the top two swains exceeded the highest yield in the Regional variety trial by 100 to 150 pounds of lint. This is the first time that so many advanced strains were tested in a given year. The site at Safford gives cotton breeders an insight as to how their advanced strains or new varieties will perform in the high deserts of Arizona and New Mexico. HVI data for the varieties in the trial indicate that the average fiber length was greater than 1.11 inches and the average fiber strength was greater than 30 grams/tex.
    • Short Staple Regional Cotton Variety Trial, Safford Agricultural Center, 1994

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Fifty five short staple varieties were grown in a replicated field trial on the Safford Agricultural Center. Germain's GC 9033, a variety with the same apparent maturity as DP 90 was the top variety for seedcotton yield but came in third place in lint yield behind two varieties from Australia. Average yields were about 200 lbs per acre lower than 1993, which were about 200 pounds per acre lower than in 1992. HW data for the varieties in the trial are included in this report.
    • Short Staple Variety Demonstations, Graham County, 1994

      Clark, Lee J.; Cluff, Ronald E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Two on farm, replicated short staple variety demonstrations were established in 1994. Fifteen varieties were evaluated on the Layton farm in Thatcher and eighteen varieties were evaluated on the Colvin farm in Eden. Several new varieties were planted in both studies. Stoneville 324 and HS 46 were the highest yielding varieties with yields of 1060 and 975 pounds of lint per acre at the Thatcher and Eden locations, respectively.
    • Short Staple Variety Trial, Greenlee County, 1994

      Clark, Lee J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Nine short staple cotton varieties including five New Mexico acalas, four California acalas were tested in the 1994 variety study. The highest yielding variety was 1517-91 with a lint yield of 1009 pounds per acre. The average yield was nearly 200 pounds per acre higher than the previous three years. 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 and 1994 is included in this paper.
    • Short Staple Variety Trials in Cochise County, 1994

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Variety trials were grown at two locations and with two different sets of short staple varieties. One dial on the Robbs farm, north of Kansas Settlement, tested eight acolas varieties from New Mexico and California. The other trial on the Curry farm, southwest of Kansas Settlement and north of Sunsites, tested twelve upland varieties as part of the statewide testing program. The latter trial was grown under drip irrigation. Yields were exceptionally high at these high elevation trials due to the record breaking heat experienced during the summer. Top yielding varieties were Prema in the acala trial and DP 5409 in the upland trial with lint yields of 892 and 1791 pounds per acre, respectively.
    • 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.
    • 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.
    • 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.
    • Timing Initial Post-plant Irrigation Based upon Plant-Water Status

      Steger, A. J.; Silvertooth, J. C.; Brown, P. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A two year study was conducted to determine the optimum timing of the initial post plant irrigation using leaf water potential (LWP) measurements. A short - season Upland cotton (Gossvpium hirsutum L.), variety DPL 20, was planted on 19 April 1993 and 15 April 1994 at the Marana Agricultural Center on a Pima clay loam (Typic Torrifluvent) soil. Treatments, designated Tl , 72, and T3, were such that the initial post plant irrigation would be applied when the midday LWP of the uppermost, fully- developed leaf exposed to full sunlight measured -15, -19, and -23 bars, respectively. All treatments received the same irrigation regime following the initial post plant irrigation. Basic plant measurements, including plant height, mainstem node number, fruit retention, number of nodes above the uppermost white bloom, fresh bloom count within a 166 -ft1 area, and percent canopy cover, were taken weekly from each plot. Soil -water data was collected at 10 inch depth increments, to a depth of 60 in. , from access tubes located in each experimental unit. Yields were 1112, 1095, and 977 lbs lint/acre in 1993 and 1082, 1035, and 964 lbs lint /acre in 1994 for T1, 72, and T3, respectively. Yields were reduced when the midday LWP was allowed to fall below -19 bars, however, reduction was significant (P 5 0.05) only in 1993. At the time of the initial post plant irrigation for each treatment, approximately 83, 62, and 32 % of the total plant available water was present in the upper 60 in. of the soil profile for Ti, 72, and T3, respectively.
    • Upland Advance Strains Cotton Variety Test at the Maricopa Agricultural Center

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