• 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.
    • 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.
    • Pima Regional 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 Pima varieties and experimental 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 data are presented in this report.
    • 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.
    • Pix - Dry Flowable vs. Liquid Formulation Performance Evaluation

      Husman, Stephen H.; Wegener, Randy; Meizler, Frank; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Cotton crop response was evaluated using the growth regulator FIX in a conventional liquid formulation compared to an equivalent rate of a newly developed dry flowable (DF) formulation. The DF formulation will be available in 1996 in water soluble packets with each 57 gram packet the equivalent of one pint liquid PIX. Both formulations regulated plant height and height:node ratios equally.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • Seasonal Infestation by Pink Bollworm of Transgenic Cotton, NuCOTN 33, and Parental Cultivar DPL-5415 in Commerical Fields

      Flint, H. M.; Antilla, L.; Parks, N. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Bolls from transgenic cotton, NuCOTN 33 (Delta and Pine Land Co.) containing the Bollgard TM gene (Monsanto Co.) and from the parental cultivar DPL-5415 were examined for mature larvae of the pink bollworm (78,240 total bolls). Bolls from five paired fields were collected in one study (Queen Creek, Buckeye, and Gila Bend areas) and a composite of 10 fields of each cultivar were collected in a second study (Paloma Ranch area). Bolls were incubated for 2 weeks (dissected late season) or dissected to find mature larvae, respectively. Collections of 100 or 80 bolls per field were made weekly or biweekly from July through November, 1995. Numbers of pink bollworm larvae were very low in all fields through August and thereafter increased steadily in the control fields. Numbers of larvae found in transgenic cotton were extremely low or non -existent throughout the season, even in fields which were adjacent to heavily infested control fields. These results show that NuCOTN 33 retained a high degree of efficacy for preventing development of mature pink bollworm larvae (diapause larvae) during the late season. Most important, these data provide baseline information against which efficacy in subsequent years can be compared.
    • 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.
    • 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.
    • 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 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.
    • Short Staple Variety Trials in Cochise County, 1995

      Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Variety trials were grown at two locations and with two different sets of short staple varieties. One trial on the Robbs farm, north of Kansas Settlement, tested eight acalas 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.
    • Susceptibility of Lygus Bug Populations in Arizona to Acephate (Orthene®) and Bifenthrin (Capture®), with Related Contrasts of Other Insecticides

      Dennehy, T. J.; Russell, T. J.; Silvertooth, Jeff; Extension Arthropod Resistance Management Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Adult lygus bugs, Lygus hesperus (Knight), were collected from alfalfa fields in 11 different cotton producing areas of Arizona. A 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 significantly less susceptible to acephate and bifenthrin in 1995, than in 1994. Resistance of lygus to acephate continues to be widespread and intense, but not uniform in Arizona. In 1995, all populations possessed individuals capable of surviving exposure to vial treatments of 10,000 μg/ml acephate. Lygus bugs from Safford and Maricopa represented the most and least susceptible populations, respectively, to both acephate and bifenthrin. These two populations were tested for susceptibility to nine other insecticides: aldiaarb (Temik®), dimethoate (Gowan Dimethoate E267®), endosulfan (Gowan Endosulfan 3EC®), imidacloprid (Admire 2F®), malathion (Gowan Malathion 8®), methamidophos (Monitor 4®®), methomyl (Lannate LV®), oxamyl (Vydate 3.77L®), apt oxydemeton- methyl (Metasystox-R SC®). The Maricopa population was significantly less susceptible to six of these insecticides. Our findings support the hypothesis that the intensive use of pyrethroid and organophosphate insecticides for whitefly control in cotton has selected for resistance in lygus. This result portends increased problems with lygus control in the future, points to the need for developing new tools for controlling lygus bugs in Arizona cotton, and underscores the urgent need to find alternatives to the current heavy reliance on insecticides for managing whiteflies in cotton.
    • 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.
    • Tillage Energy Savings from Zone Burial of Shredded and Whole Cotton Stalks

      Carter, Lyle; Chesson, Joe; Thacker, Gary; Penner, Vic; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Two prototypes of a stalk burial implement were tested for energy requirements at the University of California, Shaffer Research Station. Both versions of the implement are designed to bury the cotton stalks in a concentrated zone and reform the bed in the same location. To plow under shredded stalks, both versions of the implement required less energy than a conventional tillage systems typical of the San Joaquin Valley of California. Both stalk burial implements were also used to plow under whole cotton stalks. This offers additional energy savings by eliminating the stalk shredding operation.