• Late Season Crop Management Effects on Fiber Micronaire

      Silvertooth, J. C.; Galadima, A. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      A field experiment was conducted during the 2002 growing season to evaluate a central Arizona grower’s method of addressing cotton fiber micronaire based on the management and timing of his agronomic inputs. The success of his inseason management, irrigation termination decision combined with his method of defoliation has led to a consistent production of premium fiber micronaire in recent years. Steps to accomplish crop defoliation and the subsequent mixing of seed cotton from the top (younger) and lower (older) bolls achieved at harvest are intended to keep the micronaire at premium levels and further prevent discounts on the crop. A companion study was conducted at the University of Arizona Maricopa Agricultural Center (MAC-1,175 ft. elevation) in an effort to duplicate the grower’s late season crop management operations. This study consisted of two treatments, a control (conventional) which received an application of 10 oz. Ginstar combined with ½ pt. surfactant in 20 gal./acre carrier and a treatment which received the conventional treatment in addition to a pre-defoliation Accelerate and a post-defoliation Gramoxone applications consistent with the grower’s methods. Plant growth and development measurements taken inseason revealed that height to node ratio (HNR) and fruit retention (FR) levels estimates were similar for both sites (grower fields and MAC study). Lint yield estimates indicated no difference between the conventional defoliation and the treatment receiving additional compounds at MAC. Results of the analyses performed on final micronaire data also indicated no significant difference in micronaire values between the two methods of defoliation and late season management at MAC. Fiber micronaire values exceeded the premium level (>5.0) for both treatments at MAC. However, results obtained from the cooperator-grower gin records revealed that average fiber micronaire for all of the fields monitored in this project were at premium level (<5.0).
    • Review of the 2002 Arizona Cotton Season

      Silvertooth, Jeffrey C. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
    • Twin-Line Per Bed Plant Population and Variety Evaluation

      Husman, Stephen H.; McCloskey, Wililam B.; White, Kyrene (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Two experiments were conducted at the University of Arizona Maricopa Agricultural Center in 2002 designed to evaluate cotton yield and fiber quality at various plant populations and to test cotton variety performance in a twinline per bed cotton production system. The plant population experiment consisted of four target populations which included 60, 80, 100, and 120,000 plants per acre (PPA) and two varieties, Stoneville 4892BR and AG3601. The resulting plant populations were 52800, 69200, 82800 and 96200 for ST4892BR and 54800, 70800, 90500 and 104500 for AG3601. The two lowest plant populations resulted in the highest lint yields for both varieties and were similar but there was a significant linear of decreasing yield with increasing plant population. The highest lint yields in the twin line variety experiment were DP449BR (1743 lb/acre) and DP5415R (1702 lb/acre) which were not statistically different.
    • Effects of Reduced Tillage and Crop Residues on Cotton Weed Control, Growth, and Yield

      Adu-Tutu, K. O.; McCloskey, W. B.; Husman, S. H.; Clay, P.; Ottman, M.; Martin, E. C.; University of Arizona, Tucson, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Conservation or reduced tillage practices in cotton-based crop rotation systems were studied in field experiments initiated at Marana, Coolidge and Goodyear by planting barley cover and grain crops in the fall of 2001. In the 2002 cotton season, conservation tillage practices reduced the number of cultural operations required to grow a cotton crop. Adequate cotton weed control was achieved in conservation tillage systems using only postemergence herbicides; weedsensing, intermittent spray technology reduced the amount of herbicide spray volume used for weed control. Cotton yields in conservation tillage systems were similar to the yields in conventional tillage systems at two sites and greater at one site.
    • Arizona Upland Cotton Variety Testing Program, 2002

      Husman, S.; Norton, R.; Norton, E.; Clay, P.; Clark, L.; Zerkoune, M.; White, K.; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Each year the University of Arizona conducts variety trials across the state to evaluate the performance of upland cotton varieties. These tests provide unbiased data on the performance of varieties when tested side-by-side under typical production practices. In 2002, we planted a total of 9 trials, two in the Yuma region (Yuma County), four in the central region (Maricopa and Pinal counties), one in the southern region (Pima county), and two in the eastern region (Graham, Greenlee, and Cochise counties). We tested nine to twelve commercially available varieties at each test site. The purpose of this report is to present the results of the 2002 tests conducted in the Yuma, western, central, southern, and eastern regions of Arizona.
    • Plant Population Effect on Yield and Fiber Quality of Three Upland Cotton Varieties at Maricopa Agricultural Center, 2002

      Galadima, A.; Husman, S. H.; Silvertooth, J. C. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      A field experiment was conducted at the University of Arizona Maricopa Agricultural Center (MAC – 1100 ft. elevation) in 2002 to evaluate plant population relationships with conventional row spacing under a range of high population conditions with new Upland cotton (Gossypium hirsutum L.) varieties. The varieties, which included AG3601, DP458BR, and STV4892BR, were each planted to six densities of 15,000, 30,000, 45,000, 60,000, 75,000, and 90,000. Inseason plant measurement data revealed crop vigor and fruit retention levels were well within the optimum threshold for all varieties and populations. There was no interaction between variety and population in terms of lint yield and fiber quality parameters. However, results show significant differences in lint yield and fiber strength among varieties but not the fiber micronaire. In addition, higher population had no significant effect on lint yield or fiber quality. Higher populations had no effect in lowering fiber micronaire to premium levels as well.
    • Evaluation of Irrigation Termination Effects on Fiber Micronaire and Yield of Upland Cotton, 2000-2002

      Silvertooth, J. C.; Galadima, A. (College of Agriculture, University of Arizona (Tucson, AZ), 2003-05)
      Arizona has experienced a trend of increasing fiber micronaire values in recent years resulting in substantial discounts on fiber value. There is some evidence to suggest that irrigation termination (IT) management can influence fiber micronaire. Field studies were conducted in 2000, 2001, and 2002 at the University of Arizona Maricopa Agricultural Center (1,175ft. elevation) and in 2001 and 2002 at the Yuma Valley Agricultural Center (YVAC; 150 ft. elevation) to evaluate the effects of three dates of irrigation termination on the yield and fiber micronaire of several Upland cotton varieties. Three dates of irrigation termination (IT1, IT2, and IT3) were imposed based upon crop development into cutout. The earliest irrigation termination date, IT1 was made slightly ahead of an optimum date to provide sufficient soil-water such that bolls set at the end of the first fruiting cycle would not be water stressed and could be fully matured. Thus, the IT1 date was imposed to try to reduce overall micronaire. The second termination (IT2) date received one additional irrigation over an optimal point for the completion of the first cycle fruit set and two irrigations beyond IT1. The final (IT3) date (late September) was imposed so that soil moisture would be sufficient for the development of bolls set up through the last week of September, thus providing full top-crop potential. In general, lint yield and micronaire results revealed significant differences among the IT treatments. Micronaire and lint yield values consistently increased with later IT dates.