• 2003 Low Desert Upland Cotton Advanced Strains Testing Program

      Husman, S.; White, K.; Tronstad, Russell; Husman, Steve; Norton, Randy; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      Upland cotton advanced strains and commercial check varieties were evaluated in replicated field studies at three locations in 2003. The test sites include Safford, AZ, Maricopa, AZ, and Yuma, AZ. Seven seed companies submitted a maximum of ten advanced strains entries per location. Three commercial check varieties were used at the Safford and Yuma sites, and included ST4892BR, DP449BR, and DP565. Two commercial check varieties were used at the Maricopa site and included ST4892BR and DP449BR. Data collected included vigor and relative maturity ratings, yield, and fiber quality. The research is conducted in order to develop public unbiased performance data of genetic materials that have moved to the advanced stages of testing and are being considered for commercial release. The data has historically been used to add to seed company databases and assist with commercial release decisions.
    • Acala/Upland Cotton Variety Trial, Safford Agricultural Center, 2003

      Clark, L. J.; Ellsworth, K. F.; Norton, E. R.; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      Eight Acala varieties from New Mexico(4), California(3) and Arizona(1) along with thirteen upland varieties of interest to the area 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 this study was DP 555BR with a yield of 2203 pounds of lint per acre, but FM991BR produced the highest gross revenue per acre at $1527 per acre. Sierra, a new Acala variety from California, was the highest yielding Acala with a lint yield of 1872 pounds per acre and a gross revenue of $1324 per acre. The average lint yield was 500 pounds per acre higher that the 2002 season indicating that 2003 was an above average cotton growing year and that the heat units per day in the week following planting were above the threshold. In addition to the yield , several other agronomic variables were measured. These included plant height, total nodes, and boll weights. From plant height and total nodes the height to node ratios were calculated. Differences were seen between these variables by variety but the most notable point was that the plants were robust in their growth habit and fruiting forms were heavier than the previous year. HVI fiber quality data were reported and estimated values (in cents per pound of lint) were calculated. The HVI data showed an average fiber length of 1.13 inches, with only one variety producing a less than 1.10, and seven varieties having fiber of 1.15 inches or longer. A New Mexico experimental variety had the longest fiber at 1.18 inches. The average fiber strength was 32.1 grams per tex and the same NM experimental produced the strongest fiber. In general, all of the varieties included in this study had very good fiber.
    • Arizona Upland Cotton Variety Testing Program, 2003

      Husman, S.; Norton, R.; Norton, E.; Clay, P.; Zerkoune, M.; White, K.; Tronstad, Russell; Husman, Steve; Norton, Randy; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      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 2003, a total of 11 trials were planted. Two in the Yuma region (Yuma County), two in the western region (La Paz and Mohave counties), 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 eight to fourteen commercially available varieties at each test site. This article presents the results of the 2003 variety tests conducted at each location.
    • Comparative Efficacy and Selectivity of Acetamiprid for the Management of Bemisia tabaci

      Naranjo, Steven E.; Akey, David H.; Tronstad, Russell; Husman, Steve; Norton, Randy; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      The integrated control concept emphasizes the importance of both chemical and biological control for pest suppression in an agricultural system. A two-year field study was conducted to evaluate the selectivity of acetamiprid for controlling sweetpotato whitefly, Bemisia tabaci, in cotton compared with a proven selective regime based on insect growth regulators (IGRs) of pyriproxyfen and buprofezin. Acetamiprid was highly effective in controlling all stages of B. tabaci compared to our untreated control and generally produced lower pest densities than the IGR regime. However, six of 14 taxa of arthropod predator were significantly depressed with the use of acetamiprid compared to our untreated control, including common species such as Geocoris punctipes, Orius tristicolor, Chrysoperla carnea, Collops vittatus, Hippodamia convergens, and Drapetis nr. divergens. Compared to other independent and concurrent studies using mixtures of broad-spectrum insecticides at the same research site, acetamiprid depressed fewer populations of predator taxa in our study, but for those taxa affected, reductions from acetamiprid were larger in many cases. In contrast, only one species was significantly reduced in the IGR regime compared with the untreated control. Predator:prey ratios were generally depressed with the use of acetamiprid compared with both the IGR and untreated control regimes. Parasitism by aphelinid parasitoids was unaffected or depressed slightly in all insecticide regimes compared with the control. Although highly efficacious for whitefly control, our results suggest that acetamiprid is a poor substitute for IGRs currently used in an integrated control program for B. tabaci in cotton.
    • Comparison of Potassium Fertilizer Products and Amounts on DPL555BR Cotton, 2003

      Rethwisch, Michael D.; Reay, Mark; Quist, Aron; Cox, Tim; Grudovich, Jessica; Wellman, Jessica; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
    • Comparison of Twin and Single Line Cotton Production Systems

      Husman, Stephen H.; McCloskey, William B.; White, Kyrene; Hamilton, Jeffrey; Clay, Patrick; Norton, Randy; Norton, Eric; Zerkoune, Mohammed; Tronstad, Russell; Husman, Steve; et al. (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      Twin line (two seed lines 7.25 in apart per bed) and conventional single seed line per bed cotton production systems were compared at 18 sites across Arizona and the Palo Verde Valley near Blythe, Ca. in 2002 and 9 sites in 2003. Three experiments at the Chaffin site in 2002 compared twin line plant populations of 57,000 (57K), 75,000 (75K), and 90,000 (90K) plants per acre (ppa). In 2002, the twin line system produced more lint than the conventional single line system at 4 of 18 locations; the yields of the twin line and single line systems were 1273 and 1186 lb/acre, 1572 and 1461 lb/acre, 1478 and 1290 lb/acre, and 1309 and 1210 lb/acre, respectively, at the Grasty, Ramona, Rovey, and Wells sites, respectively. In 2003, none of the experiments resulted in higher twin line system lint yields. In 2002, there were no significant differences in yield or fiber micronaire in 7 of the 18 experiments. In 2003, there were no significant differences in yield in 3 of the 9 experiments. In 2002, the twin line system produced less lint than the conventional system at 5 of 18 locations; yields of the twin line and single line systems were 2019 and 2189 lb/acre, 1400 and 1489 lb/acre, 1537 and 1845 lb/acre, 1065 and 1200 lb/acre, and 1271 and 1431 lb/acre, respectively, at the Chaffin (75K), Cooley, Hull, Papago, and Wakimoto sites, respectively. In 2003, the twin line system resulted in less yield in 6 of the 9 experiments; yields of the twin line and single line systems were 1154 and 1285 lb./acre, 1906 and 2109 lb./acre, 1797 and 1938 lb./acre, 878 and 1114 lb./acre, 726 and 821 lb./acre, and 1230 and 1404 lb./acre, respectively, at the Hull, Marlatt 1, 2,, 3, Murphy Late Plant, and the University of Arizona (UA) Marana Agricultural Center sites respectively. In 2002, fiber micronaire was reduced in five experiments; the micronaire values were 4.25 and 4.73, 4.46 and 4.78, 4.60 and 4.85, 4.76 and 4.98, and 4.93 and 5.15, in the twin line and single line systems, respectively, at the Rogers, Papago, Grasty, Hull, and Perry sites, respectively. In 2003, there were no significant differences in fiber micronaire at all 9 test locations. In 2003, visual observations suggested that the spindle pickers were unable to effectively harvest bolls the lowest bolls primarily below the cross-over point of the two2 mainstems cross in the twin line system. Hand harvest comparisons of the twin and single line system resulted in yields of 1776 and 1661 lb./acre respectively, a 6% difference at the Maricopa Agricultural Center. It was concluded that tThe inability to effectively harvest the twin line cotton is the most significant system problem with this production system.
    • Conservation Tillage Effects on Infiltration and Irrigation Advance Times in Arizona Cotton

      Martin, E. C.; Adu-Tutu, K. O.; McCloskey, W. B.; Husman, S. H.; Clay, P.; Ottman, M.; Tronstad, Russell; Husman, Steve; Norton, Randy; University of Arizona, Tucson, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      Field experiments were initiated in 2001 for a cotton-based conservation tillage project at sites in Marana, Coolidge, and Goodyear, Arizona. For the 2002 season, soil and water management assessments were made to evaluate surface irrigation performance under conservation tillage, following cover and grain crops. An additional site was added in the winter of 2002 at Maricopa, Arizona. Analyses included soil texture, infiltration rate, and water advancement. At Coolidge, conservation tillage plots had higher infiltration rates and longer advance times than the conventional plots in 2002 and 2003. At Marana, infiltration rates were initially higher for the Conservation plots but the rates converged at the end of four hours in 2002. In 2003, Conventional plots infiltrated about one inch more. Advance times for Marana showed water infiltration for Conventional wheel rows to be the fastest. At Goodyear, Conservation plots infiltrated more than Conventional plots during 2002. This also resulted in a slower advance time for the Conservation plots. In 2003, treatment effects were not comparable due to tillage by the grower. At Maricopa, Conservation plots infiltrated almost 2.2 inches more water than Conventional plots and water reached the end of the field three hours ahead of the fastest Conservation plot. Seasonal irrigation water applications to each treatment were relatively equal for all sites with the exception of Coolidge. Here, the long field combined with sandy soil made it difficult to adequately irrigate the Conservation plots. In 2002, an additional 21 inches of water was applied to the Conservation plots. In 2003, that amount was reduced to 12.5 inches. The yield data show a significant difference in 2002 only at Coolidge. There, Conservation plots yielded more than the Conventional ones. This may have been due to more water applied to the Conservation plots. In 2003, the opposite occurred with the Conventional plots yielding more than the Conservation plots. This could have been due to herbicide damage. At Maricopa, the Conventional plot also yielded more than the Conservation plot. Initial indications are that the conservation tillage does impact irrigation performance and may not be suitable for all locations depending on soil type and field layout.
    • Effects of Megafol and Calcium Metalosate® Applications at Early Bloom on April 2003 Planted DPL555BR Cotton

      Rethwisch, Michael D.; Reay, Mark; Cox, Tim; Grudovich, Jessica; Wellman, Jessica; Hawpe, Erica; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      Foliar fertilizers are not widely used for cotton production in the low desert, and data about their effects on cotton production under these conditions is therefore limited. This study documented the effects of Calcium Metalosate7 and Megafol, each applied at the rate of 1 qt/acre to DPL555BR cotton. Treatments were applied on July 7, and plants had been growing vigorously just prior to application. Plots were approximately 0.75 acres in size with four replications. Plant mapping data from late July indicated that non-treated cotton had numerically higher retention rates at each of the first three fruiting positions mapped in addition to slightly more total nodes and a greater number of reproductive nodes in part due to first fruiting structure being retained lower on the plant (node 6.75) than treated cotton (node 7.95 for Megafol, node 8.4 for Calcium Metalosate7). Tractor passage through treated plots may have also knocked off developing squares however. No statistical differences were noted for lbs. of lint/acre, although treated cotton did have slightly higher yields than the untreated check (1,162 lbs/acre) and treatments were almost identical (1,203 lbs./acre for Megafol; 1,198 lbs./acre for Calcium Metalosate7). Fiber lengths and strengths were significantly different by treatment, with shortest and weakest fibers resulting from cotton treated with Megafol. Cotton from Calcium Metalosate7 treatments were significantly longer and stronger than lint from Megafol treated cotton plots, but lint from untreated cotton plots was significantly longer and stronger than either treatment (36.6 staple, 31.0 g/tex). The reasons for these differences are unclear. It is difficult to correlate the slight yield increases noted with treatments in early July, especially in light of lower retention rates noted with treatments from plant mapping data in late July and the large amount of lint production that occurred in late 2003 due to summer heat. Multiple differences were noted for treatments in regards to lint quality, however, indicating treatments did affect cotton production. Size of bolls and cotton lint from these early summer bolls was not obtained but may have been an overlooked aspect of this study.
    • Late Planted DPL451BR Cotton Responses to Plant Growth Enhancement Products Applied at Three Crop Development Stages in Palo Verde Valley, 2003

      Rethwisch, M. D.; Reay, M.; Chaffin, G.; Perez, R.; Grudovich, J.; Wellman, J.; Hawpe, E.; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      An experiment to investigate the effects of several plant growth enhancement products (AuxiGro7 WP, FirstChoice7 Bollster, CalMax, FoliGro7 BollSet) on DPL 451BR was conducted in the Palo Verde Valley. The cotton field chosen for this project was planted in April 2003, and flowering and boll/lint production was highly affected by summer heat, therefore product effectiveness was tested under the extreme high temperatures conditions that existed in 2003. Products were applied July 11 (shortly after first bloom), August 1st and/or August 15. Three rates (1, 2, 4 oz./acre) of AuxiGro7 WP were applied at each date, although just a single rate of other products was evaluated. Data collected included plant mapping following the first two application dates as well as lint yield and quality at harvest on October 20-23. Data indicated rate effects for treatments containing AuxiGro7 WP as noted in response to applications on August 1 (retention rates) and August 15 (cotton quality factors). These responses were signficantly different than the untreated check, and were often signficantly different than the Bollster fertilizer treatment itself as though Bollster was also included with AuxiGro7 WP treatments. Although yields for any treatment and the untreated check were not significantly different, previously noted differences for retention for the AuxiGro7 WP treatments may not have been realized due to the high temperatures and extended periods of not only Level 1 but Level 2 stress during the course of the experiment. Cotton values per acre were highest ($609.85/acre) in the 4 oz/acre of AuxiGro7 applied on August 15, due to highest valued lint as a result of micronaire of 5.2 combined with increased fiber strength and fiber length. Application of CalMax resulted in a significant increase in fiber strength following two applications of 4 oz./acre of AuxiGro7 + Bollster, but CalMax following two applications of Bollster did not affect fiber strength when compared with each of the two application treatments. A third application of FoliGro7 BollSet was detrimental for cotton yields and strength compared with only two applications of this product, although both treatment regimens resulted in shorter fibers that were not quite as strong as the untreated check.
    • Late Season Crop Management Effect on Fiber Micronaire

      Silvertooth, J. C.; Galadima, A.; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      A field experiment was conducted during the 2002 and 2003 growing seasons to evaluate a central Arizona grower’s method of addressing high cotton fiber micronaire based on the management and timing of agronomic inputs. In-season management and irrigation termination combined with defoliation methods has led to 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 in 2002 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 1/2 pt. surfactant in 20 gal./acre carrier and a treatment which received the conventional treatment in addition to a predefoliation of Accelerate and a post-defoliation of Gramoxone, consistent with the grower’s methods. At the grower’s location, data was collected during the 2002 and 2003 seasons. In 2002 and 2003, plant growth and development measurements taken in-season revealed that height to node ratio (HNR) and fruit retention (FR) levels tracked well and were similar for both sites and years (grower’s fields and MAC study). Lint yield estimates indicated no difference between conventional defoliation and the treatment receiving additional compounds at MAC in 2002. Average yield estimates were high for the cooperator-grower fields in both the 2002 and 2003 seasons. Results of the analysis performed on final micronaire data indicated no significant difference in micronaire values between the two methods of defoliation and late season management at MAC. In addition, fiber micronaire values exceeded the premium level (>5.0) for both treatments at MAC. In contrast, the data of 2002 and 2003 obtained from the cooperator-grower gin records revealed consistent results for average fiber micronaire for all of the fields monitored in this project which were at premium levels (<5.0).
    • Mepiquat Formulation Evaluation in southeastern Arizona

      Norton, E. R.; Clark, L. J.; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      A series of experiments were conducted in 2003 in the Upper Gila River Valley in Safford, AZ to evaluate several different formulations of the plant growth regulator (PGR) Pix manufactured by BASF. Two experiments were conducted at the Safford Agricultural Center (SAC) while the third was conducted on a grower-cooperator field in the same valley. Experiments conducted at SAC involved evaluating the four formulations of Pix (Pix, Pix Plus, Pix Ultra, and Pentia) in a standard (STD) treatment regime and a low rate multiple (LRM) regime. The untreated control plots in both the LRM and STD experiments produced higher yields than any of the other PGR formulations. Comparing only the PGR formulation treatments the Pentia treatment produced the highest yield in both the STD and LRM experiments. No significant differences were observed in fiber quality for either the LRM or STD experiment. The third experiment conducted on a growercooperator field was a Pentia demonstration experiment. Three treatments including a control, a standard, single Pentia application, and an aggressive split application of Pentia were employed. The highest yield was produced in the most aggressive Pentia treatment. Results from this set of experiments demonstrate the importance of incorporating information from plant monitoring techniques when making decisions about PGR applications.
    • Phosphorous Fertility Evaluation in Graham County

      Norton, E. R.; Clark, L. J.; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      This project is a continuation of an ongoing phosphorus (P) fertility evaluation that began in 1998, at Safford, AZ on a grower cooperator field. The field study conducted during the 2003 season consisted of five treatments of varying rates of P fertilizers from 0 through 165 lbs. of P₂O₅ per acre. Treatments were arranged in a randomized complete block design with three replications. Plot sizes were 12, 36 in. rows wide and extended the full length of the irrigation run of 1250 feet. Three of the five treatments (treatments 3, 4, and 5) consisted of varying rates of P fertilizer applied as a liquid blend (11-30-0-5S) proprietary to United Agri Products (UAP) injected in the soil at approximately the 4 leaf stage prior to the first post plant irrigation. An additional treatment (treatment 2) of calcium thiosulfate (CATS) proprietary to Tessenderlo-Kerley was also applied. In an effort to ensure uniform application of fertilizer nitrogen (N) across all treatments, a solution of urea-ammonium-nitrate (UAN) was applied to bring uniform the level of all treatments with respect to N fertilizer. Lint yield results indicate a strong positive response to applied P, consistent with the previous fours years of P fertility work done in this area. The highest applied P treatments resulted in the highest lint yields with an increase of approximately 155 lbs. lint/acre above the control, an increase of about 12%. Fiber quality data did not indicate any significant differences among treatments for any of the fiber quality parameters measured. Compiling all yield data from the prior six years and plotting percent relative yield as a function of applied P fertilizer demonstrates a positive response to P fertilization. These results indicate the need for local growers to consider P fertilization as an important component of their fertility program. This is particularly true for cotton fields that have had very little or no rotation with small grain crops that are commonly fertilized with a P based fertilizer such as 16- 20-0.
    • Pima Cotton Regional Variety Trial, Safford Agricultural Center, 2003

      Clark, L. J.; Carpenter, E. W.; Norton, E. R.; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      This study is part of the Regional Pima cotton variety testing program that is carried out in 8 locations from the West Side Field Station in California to El Paso, Texas. Additional varieties are added to the regional standards in this study to supply information needed by cotton growers in southeastern Arizona. Seventeen 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. Yields were exceptionally high this year with an average yield nearly 600 pound per acre more than was harvested in 2002. The highest yielding variety in this study was Hazera (HA) 195 with a yield of 2027 pounds of lint per acre. This interspecific hybrid , from Israel, has been the highest yielding variety in the study since it was included in 2001. This fuzzy seeded hybrid has fiber qualities as follows: length - 1.41 inches, strength - 34.8 g/tex and uniformity of 87.5. The averages from this study were 1.43, 42.5 and 88.3 for these same variables, respectively. DP HTO was the highest yielding non-hybrid variety in the study with a yield over 1900 pounds of lint per acre. For comparison purposes, it=s length, strength and uniformity were: 1.39, 41.9 and 88.5. Other varieties in the top half of the study were: HA 14-08, OA 360, OA 359, HA 7-66, DP 340 and DP 744, in descending order of their yields. Yield and other agronomic data as well as fiber quality data are contained in this paper along with estimated values of the lint.
    • Plant Population Effects on Twin Line Cotton Production

      Husman, Stephen H.; McCloskey, William B.; White, Kyrene; Tronstad, Russell; Husman, Steve; Norton, Randy; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      Three experiments at the University of Arizona Maricopa and Marana Agricultural Centers in 2002 and 2003 measured effect of plant populations on the yield of cotton planted in the twin seed-line per bed configuration. In 2002 at the Maricopa Ag. Center, the plant populations were 52800, 69200, 82800 and 96200 plants per acre (PPA) for Stoneville 4892BR and 54800, 70800, 90500 and 104500 PPA for AG3601, respectively. The two lowest plant populations which were in the range of common commercial plant densities resulted in the greatest lint yields for both varieties (an average of 1708 and 1287 lb lint/A for ST4892BR and AG3601, respectively) but there was a significant linear decrease in yield with increasing plant population. In 2003, the cotton variety Delta Pine 449BR was planted and the population densities were 22000, 29000, 36000, 46000, 51000, 61000, and 64,000 PPA at the Marana Ag. Center and 24000, 34000, 41000, 56000, 63000, 71000, and 86,000 PPA at the Maricopa Ag. Center. Cotton yield did not vary significantly as a function of population density at Maricopa and averaged 1526 lb lint/A. At Marana there was a slight trend of increasing yield with increasing plant densities with the three highest plant populations averaging 1385 lb lint/A. In the experiments with ST4892BR and AG3601 at Maricopa in 2002 and with DP449BR in 2003 there was a linear decrease in fiber micronaire with increasing density but this effect of density on micronaire was not observed possibly because plant populations Marana were lower than in the other experiments.
    • Planting Date by Variety Evaluation in Graham County

      Norton, E. R.; Clark, L. J.; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      A single field study was established to evaluate the effects of planting date (PD) on the yield and fiber quality characteristics of several cotton varieties commonly grown in the Upper Gila River Valley of Safford. Eight varieties selected for evaluation in 2003 ranged from medium to medium-full varieties. These varieties included two Delta and Pine varieties (DP555BR and DP655BR), two Fiber Max varieties (FM989BR and FM991BR), two Stoneville varieties (ST5303R and ST5599BR), one CPCSD variety (Riata), and one variety from the Arizona Cotton Growers Association breeding program (AG3601). These eight varieties were planted on three separate planting dates (1 April, 23 April, and 12 May; 341, 525, and 779 heat units accumulated after January 1, respectively) in a split-plot within a randomized complete block design with four replications. Overall analysis of variance revealed significant differences due to main effects (PD; OSL=0.00043), sub effects (variety; OSL=0.0029), and interaction effects (PD*variety; OSL=0.0266). Extremely cool conditions surrounding the first PD resulted in significantly lower yields that the other two planting dates. Yields for PD 1 ranged from 506 lbs. lint/acre to about 850 lbs. lint/acre with DP555BR producing the highest and CPCSD Riata producing the lowest yield. Conditions surrounding the second PD were much improved over PD 1. However, soil temperatures still hovered near to and below the optimum temperature of 65oF. Yields were dramatically higher in PD 2 when compared to PD 1, ranging from a low of 847 lbs. lint/acre (AG3601) to 1139 lbs. lint/acre (FM991BR). PD 3 resulted in the best conditions for seedling emergence and stand establishment and produced the highest yield. Yields ranged from a low of 945 lbs. lint/acre (CPCSD Riata) to 1465 lbs. lint/acre (FM991BR). Fiber quality data demonstrated a couple of interesting trends. Micronaire tended to increase with later plantings for most varieties while fiber length had an inverse relationship with PD. Micronaire levels tended to be high enough to be discounted for every variety in at least one and usually two PDs, except for Riata. Riata had the lowest micronaire, and the longest and strongest fiber grades. These results are consistent with other evaluations of the high fiber quality associated with many of the California Acala varieties. However, relatively lower yields for this variety currently make it an unsuitable variety for this region despite the high fiber quality. Results from this evaluation demonstrate the importance of monitoring soil temperature and keeping a close eye on local weather forecasts when making planting date decisions regardless of the calendar date.
    • Preliminary Screening of Different Cottons for Resistance to Sweetpotato Whitefly Infestations

      Alexander, PJ.; Forlow Jech, L.; Henneberry, T. J.; Tronstad, Russell; Husman, Steve; Norton, Randy; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      Cotton, Gossypium spp., varying in leaf color (green vs. red), leaf shape (normal vs. okra) and leaf hairs per cm2 of leaf area were evaluated for sweetpotato whitefly (SPW), Bemisia tabaci (Gennadius) Biotype B preference. Regression analysis showed SPW adults, eggs and nymphs were significantly related to leaf hairiness. Seasonal mean numbers of SPW adults, eggs, and nymphs were high variable within and between leaf color, shape, and hairiness types. Further studies are justified since some of the cottons may be potential sources of SPW resistant germplasm.
    • Reduced Tillage and Crop Residue Effects on Cotton Weed Control, Growth and Yield

      Adu-Tutu, K. O.; McCloskey, W. B.; Husman, S. H.; Clay, P. A.; Ottman, M. J.; Martin, E. C.; Teegerstrom, T.; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      The tillage operations conducted in a barley and cotton double-crop rotation were reduced by eliminating tillage prior to planting cotton, eliminating cultivations for weed control in cotton, and especially by eliminating tillage following cotton prior to planting barley. Data collected in 2002 and 2003 in Coolidge and Marana showed that a weed sensing, automatic spot-spray system reduced the amount of spray volume and herbicide used by 50 to 60%. Data from Maricopa in 2003 indicated that the savings can be much greater (e.g., in a treatment with thick Solum barley cover crop residues) or much less if volunteer grain germinates after grain harvest. Similar weed control was obtained with the weed sensing, automated spot-spray system compared to conventional continuous spray systems for most weed species. At Coolidge in 2002, the minimum tillage treatment with a barley cover crop produced 24% more lint than the conventional tillage system (1089 versus 880 lb/A) because more water was applied in that treatment. In 2003, the minimum tillage treatment yielded 24% less than the conventional tillage treatment (1178 versus 1539 lb/A) due to herbicide injury. There were no differences in cotton yields among the tillage systems at Goodyear in 2002 and 2003. In Marana (2002 and 2003) and Maricopa (2003), there were yield differences between treatments related to planting date, with late-planted cotton yielding less than early-planted cotton. At Marana, the cotton yields of the minimum-till and conventionally tilled treatments were not statistically different. At Maricopa, the early-planted minimum-till cotton yielded less than the early-planted conventionally tilled cotton (956 versus 1141 lb/A). The yield comparisons between conservation tillage and conventional tillage cotton production systems are not yet definitive and more research needs to be conducted. Economic comparisons between productions systems indicated an advantage for conservation/minimum tillage treatments if cotton yields were comparable.
    • Residual Soil Nitrogen Evaluations in Irrigated Desert Soils, 2003

      Silvertooth, J. C.; Galadima, A.; Norton, E. R.; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      Field experiments aimed at investigating N fertilizer management in irrigated cotton production have been conducted for the past 16 seasons at three University of Arizona Agricultural Centers (Maricopa, MAC; Marana, MAR; and Safford, SAC). In 2003, residual N studies were conducted at two of these locations (MAC and MAR). The MAC and SAC experiments have been conducted each season since 1989 and the Marana site was initiated in 1994. Original purposes of the experiments were to test nitrogen (N) fertilization strategies and to validate and refine N fertilization recommendations for Upland (Gossypium hirsutum L.) and American Pima (G. barbadense L.) cotton. Each experiment has 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 fruit retention levels and N needs of the crop. This pattern was further reflected in the final yield analysis as a response to the N fertilization regimes used. The higher, more aggressive N application regimes did not consistently benefit yields at any location. Generally, the more conservative, feedback approach to N management provided optimum yields at all locations. In 2001, a transition project evaluating residual N effects associated with each treatment regime was initiated with no N fertilizer applied. Therefore, all N taken-up by the crop was derived from residual soil N. In 2001, 2002, and even 2003 there were no significant differences among the original fertilizer N regimes in terms of residual soil NO₃⁻-N concentrations, crop growth, development, lint yield, or fiber properties. Lint yields were very uniform at each location in 1991 and averaged 1500, 1100, and 850 lbs. lint/acre for MAC, MAR, and SAC, respectively. In 2002, results were very similar and yields averaged 1473 and 1060 lbs. lint/acre for MAC and MAR locations respectively. The results for 2003 were similar to the results of the prior two years with yields at 1322 and 1237 lbs. lint/acre for MAC and MAR, respectively. Trends associated with residual fertilizer N effects are not evident at either location following three consecutive seasons of N fertilizer treatments.
    • Review of the 2003 Arizona Cotton Season

      Tronstad, Russell; Husman, Steve; Norton, Randy; Norton, Eric; Clay, Pat; Zerkoune, Mohammed; Tronstad, Russell; Husman, Steve; Norton, Randy (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
    • Round Ready Flex Cotton: Glyphosate Tolerance and Weed Management 2002-2003

      McCloskey, William B.; Adu-Tutu, Kwame O.; Hicks, T. Vint; Tronstad, Russell; Husman, Steve; Norton, Randy; Department of Plant Sciences, University of Arizona, Tucson, AZ; Monsanto Company, Fountain Hills, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2004-05)
      The tolerance of Roundup Ready (RR) Flex cotton to topical Roundup Weathermax (glyphosate) applications and weed management programs in RR Flex cotton were studied in 2002 and 2003 at the University of Arizona Maricopa Agricultural Center. RR Flex cotton demonstrated excellent tolerance to glyphosate as measured by flower pollen shed and lint yield when sprayed topically with glyphosate at 2.25 lb ae/A four times (at the 3 leaf, 6 node, 10 node and 14 node growth stages). Line 1445 containing the current commercial RR genetic construct had a flower sterility/pollen shed rating of 4.6 (1 equals full pollen shed and 5 equals no pollen shed) on 28 June 2003 compared to ratings of 1.1 to 1.9 in lines containing the RR Flex genetic construct. Cotton yields followed a similar pattern with 1145 yielding 386 lb seed cotton/A compared to 1477 to 1894 lb seed cotton/A for the best lines containing the RR Flex genetic construct (yields were generally low because all lines had a Cocker genetic background that is not adapted to hot desert production conditions.) The presence of the RR gene did not affect the yield of genotype pairs that were identical except for the presence or absence of the RR Flex genetic construct. In the weed management study, delaying the first topical glyphosate application resulted in larger, more difficult to control weeds and reduced cotton yield by allowing greater early season competition between weeds and cotton. The best weed control programs included early (1 to 2 leaf growth stage) topical applications at rates greater than 0.75 lb ae/A and a second Roundup application after the first post-planting irrigation (10 node growth stage). The data also suggested that there may be significant value in making a layby, directed-broadcast application that includes a residual herbicide such as prometryn at layby.