• Evaluation of Potassium Fertility in a Common Agricultural Soil of Arizona

      Silvertooth, J. C.; Galadima, A. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Two field experiments were conducted during the 2001 growing season to address potassium (K) fertility response of two commonly grown varieties of cotton in Arizona. The studies were conducted near Coolidge, AZ in two separate fields and each consisted of two treatments, an untreated control and a treatment receiving a preseason side-dress application of K fertilizer. Plant growth and development estimates revealed that fruit retention (FR) and height to node ratio (HNR) levels were similar for both treatments in both fields. Lint yield data also indicated no difference between the fertilized and unfertilized treatments in both fields.
    • Planting Method and Seeding Rate Evaluation in Graham County

      Norton, E. R.; Clark, L. J.; Carpenter, E. W. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      A single field experiment was established in 2001 at the Safford Agricultural Center to evaluate the effects planting method and seeding rate have on plant population and yield of an Upland cotton cultivar Deltapine DP655BR. Two planting methods; planting into moisture (pre-irrigate) and dry plant/water-up, were main effects with three seeding rates of 10, 20, and 30 lbs./acre as sub-effects. These effects were evaluated with respect to stand establishment and yield. Analysis of variance showed no significant differences with respect to planting method for either plant population or yield, so data was combined across main effects. Significant differences were observed in plant population and yield as a function of seeding rate. A linear increase in yield with plant population was observed. These results are not consistent with previous research performed examining plant population effects on yield. This experiment will be conducted again in 2002 in an effort to validate results observed in 2001.
    • Sweetpotato Whitefly Nymph Mortality and Adult and Nymph Honeydew Production Following Treatment with Applaud or Knack

      Henneberry, T. J.; Forlow Jech, L.; Hendrix, D. L.; de la Torre, T.; Maurer, J.; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Cotton lint contamination from honeydew excreted by sweetpotato whiteflies, Bemisia tabaci (Gennadius), is a serious problem in the textile industry resulting in reduced lint processing efficiency. The insect growth regulators, Applaud® and Knack®, provide effective control of sweetpotato whiteflies on cotton by interfering with their reproduction and development. Protection from honeydew lint contamination is attributed to reduced sweetpotato whitefly populations. We investigated the potential direct effect of Applaud and Knack on sweetpotato whitefly honeydew production. In the field, amounts of the major sugar components of honeydew produced by adults and nymphs collected on day six following Applaud or Knack applications to cotton field plots were not significantly different compared to amounts produced by those collected from untreated plots. In the laboratory, adult mortality and amounts of honeydew sugars produced by adults were not affected by confinement for 48 h on Applaud or Knack residues from cotton leaf dips or following nebulizer contact spray applications. In contrast, mortality of first and second instar nymphs on leaves was higher on day six following leaf dips in Applaud solutions compared with leaf dips in Knack or water solutions. Nymph mortality on day six following leaf dips in Knack solutions was higher than mortality of nymphs following leaf dips in water. Honeydew collected during the period between two to 50 h after leaf dip treatment had reduced amounts of glucose, fructose and trehalulose, but not sucrose and melezitose per nymph compared with honeydew from nymphs on leaves dipped in water. Results were more variable for sugars in honeydew collected 96 to 144 h after leaf dip treatment. Nebulizer sprays of Applaud and Knack to nymphs on cotton leaves also resulted in reduced amounts of sugars in honeydew and nymph mortality following treatments.
    • Planting Date by Variety Evaluation in Graham County

      Norton, E. R.; Clark, L. J.; Carpenter, E. W. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      A single field study was established in 2001 at the Safford Agricultural Center to evaluate the effects of planting date and variety on crop growth and yield. Ten varieties were selected and planted on three separate planting dates in a split-plot randomized complete block design with four replications. Results from this experiment indicated significant differences due to planting date and variety. The interaction between planting date and variety was not significant. Yield trends were increasing with later planting dates which is thought to be a function of the inclement weather conditions surrounding particularly planting date one but also two. This experiment provides some interesting results with respect to seedling vigor, survivability, and ultimately yield for the different varieties tested.
    • Short Staple Variety Trial in Cochise County, 2001

      Clark, L. J.; Norton, E. R. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Twelve varieties were tested including three New Mexico Acalas and one Acala from Buttonwillow Research in California, six Roundup Ready varieties, five of which also contained the Bt gene, along with a couple of other varieties were planted including FiberMax 989, which has been the highest yielding variety in the trial for two of the past three years. The highest yielding variety in the trial was FiberMax 989R, the Roundup Ready version of FM 989, with a yield over 950 pounds of lint per acre. 1517-95 and SureGrow 521RR followed in yield. Yields were considerably lower than seen in the previous year’s study (1). Several Roundup Ready varieties were included in this study. Plant mapping data and HVI data are also included in this report.
    • Evaluation of a Twin-Line Cotton Production System in Graham County

      Norton, E. R.; Clark, L. J.; Carpenter, E. W.; Husman, S. H.; McCloskey, W. M.; Clay, P. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      A single field study was established in 2001 at the Safford Agricultural Center to evaluate a twin-line cotton production system. This location was part of a larger, statewide program conducted in 2001. This location consisted of two separate planting dates (PD) in which two separate planting systems were used. Results from this location indicated trends in yield increases with the twin-line production system when compared to the single or conventional production system. Lint yield increases of approximately 200 lbs. lint/acre were observed on the second PD. Lower yields were observed in the twin-line planting with the first PD which was in part due to poor seed placement with the equipment used to plant the twin-line on the first PD. Results indicate the potential for increased yield with the twin-line production system with the caveat that the proper equipment be used to plant the twin-line system to ensure precise and consistent seed placement and spacing.
    • Phosphorus Fertility Evaluation in Graham County

      Norton, E. R.; Silvertooth, J. C.; Clark, L. J. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      A series of three phosphorus (P) fertility experiments were conducted in 2001 in Graham County. These studies follow similar experiments conducted over the past three seasons. Results from 2001 were consistent with previous results indicating a positive relationship between yield and P fertilizer applications in relation to soil test indices. Modest yield increases were observed from a minimum of 25 to 80 lbs. lint per acre with an application of approximately 70 lbs. of P as P₂O₅ per acre. Yield differences from previous years have been as great as 170 lbs. of lint per acre. With the increased use of UAN-32 as a primary fertilizer source and a reduction in the application of P fertilizers, which is typically associated with a rotation of small grains, a depletion of soil P is a potential result. A continuation of this research with varying rates of P fertilizer will take place in 2002 in an attempt to relate soil test P levels to yield increases observed in recent years. The results of this research demonstrate the possible need for a return to use of fertilizers with supplemental P for optimum yields that would be predictable based on soil test results.
    • Arizona Upland Cotton Variety Testing Program, 2001

      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), 2002-06)
      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 2001, we planted a total of 12 trials, one in the Yuma region (Yuma county), two in the western region (La Paz and Mohave counties), five in the central region (Maricopa and Pinal counties), one in the southern region (Pima county), and three in the eastern region (Graham, Greenlee, and Cochise counties). We tested seven to twelve commercially available varieties at each test site. The purpose of this report is to present the results of the 2001 tests conducted in the Yuma, western, central, southern, and eastern regions of Arizona.
    • Review of the 2001 Arizona Cotton Season

      Silvertooth, Jeffrey C. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
    • Pima Cotton Regional Variety Trial, Safford Agricultural Center, 2001

      Clark, L. J.; Carpenter, E. W.; Norton, E. R. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Twenty 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 this study was HAZ 195 with a yield of 1408 pounds of lint per acre. This interspecific hybrid possessing a “fuzzy” seed and was tested with the Acala varieties in 2000, but was included in the Pima study this year because of it’s fiber characteristics. OA 345 was the highest yielding nonhybrid variety in the study, it yielded nearly 800 pounds of lint per acre. Yield and other agronomic data as well as fiber quality data are contained in this paper along with estimated values of the lint.
    • 2001 Low Desert Upland Cotton Advanced Strains Testing Program

      Husman, S.; Coyle, G.; White, K.; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Upland cotton advanced strains and commercial check comparison varieties were evaluated in replicated field studies at three locations in 2001. The test sites include Yuma, AZ., Maricopa, AZ., and Safford, AZ.. Nine seed companies submitted a maximum of six advanced strains entries per location. Four commercial check varieties were used at Maricopa and Safford-DP5415, NuCOTN33B, SG747, and ST474. Five commercial check varieties were used at Yuma-DP5415, DP33B, SG747, ST474, and DP451BR.
    • Looking for Functional Non-Target Differences Between Transgenic and Conventional Cottons: Implications for Biological Control

      Naranjo, Steven E.; Ellsworth, Peter C.; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ; University of Arizona, Maricopa, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Evaluations of the non-target effects of transgenic cotton, modified to express the insecticidal proteins of Bacillus thuringiensis (Bt), have been underway in Arizona since 1999. Here we provide a preliminary report of replicated field studies conducted from 1999 to 2001 to examine comparative affects of Bt cotton on natural enemy abundance, overall arthropod diversity, and natural enemy function. Analyses completed to date indicate that natural enemy abundance and overall arthropod diversity are affected by use of additional insecticides for other pests, but not directly by transgenic cottons in comparison with non-transgenic cottons. Further studies suggest that natural enemy function, measured as rates of predation and parasitism on two key pests (Pectinophora gossypiella (Saunders) and Bemisia tabaci (Gennadius)) of cotton in the western U.S., is unaffected in Bt cotton. Our preliminary results suggest that use of transgenic cotton may not have any unintended effects and represents an extremely selective pest control method that could facilitate the broader use of biological control and IPM in an agricultural system long dominated by the use of broad-spectrum insecticides.
    • Short Staple Variety Trian in Virden, NM, 2001

      Clark, L. J.; Norton, E. R. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Twelve varieties were tested including three New Mexico (NM) Acalas and one Acala from ButtonWillow Research in California, six Roundup Ready varieties, five of which also contained the Bt gene, along with a couple of other varieties were planted including FiberMax 989R, the Roundup Ready version of FM 989, which was the highest yielding variety in the trial for two of the past three years. The highest yielding variety in the trial was SureGrow 215BR, the stacked (Bt/Roundup Ready version of SG 125), with a yield near 925 pounds of lint per acre. FM 989R and DP 436BR followed SG 215BR in yield with yields not significantly different from the leader. Yields were slightly lower than seen in the previous year’s study (1). Plant mapping data and fiber quality (HVI) data are also included in this report along with lint value estimates and crop value per acre.
    • Evaluation of Crop Management Effects on Fiber Micronaire, 2000-2001

      Silvertooth, J. C.; Galadima, A.; Tronstad, R. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Arizona has experienced a trend toward increasing fiber micronaire values in recent years resulting in substantial discounts on fiber value. There is some evidence to suggest management can influence fiber micronaire. Approximately 400 cases were identified in cotton production areas in Arizona ranging from the lower Colorado River Valley to near 2,000 ft. elevation with grower cooperators in the 2000 and 2001 seasons. Field records were developed for each field by use of the University of Arizona Cotton Monitoring System (UA-CMS) for points such as variety, planting date, fertility management, irrigation schedules, irrigation termination, defoliation, etc. Routine plant measurements were conducted to monitor crop growth and development and to identify fruiting patterns and retention through the season. As the crop approached cutout and the lower bolls began to open, open boll samples were then collected from the lowest four, first position bolls (theoretically the bolls with the highest micronaire potential on the plant) from 10 plants, ginned, and the fiber analyzed for micronaire (low 4). From that point forward, total boll counts per unit area and percent open boll measurements are being made on 14-day intervals until the crop is defoliated. Following defoliation, final plant maps were performed. Relationships among low 4 sample micronaire, irrigation termination (IT), defoliation, and final crop micronaire were analyzed. Results indicate strong relationships with final fiber micronaire for factors such as total heat units (HU) accumulated by the crop from planting to IT, variety, region of production (environment), and green boll load at cutout. Results showed that as total HU accumulated from planting to IT exceeded approximately 2950 HU, micronaire levels significantly increased.
    • Acala Cotton Variety Trial, Safford Agricultural Center, 2001

      Clark, L. J.; Carpenter, E. W.; Norton, E. R. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Six New Mexico and California Acala cotton varieties were tested along with three upland varieties with good quality and excellent yield potential 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 655BR with a yield of 1367 pounds of lint per acre. The next highest variety was Fiber Max 989. This latter variety, while not officially classified as an Acala, produced the longest fiber in the study. Yield and other agronomic data as well as fiber quality data are contained in this paper.
    • Effect of Buctril Rate on Weed Control in BXN® Cotton - 2001

      McCloskey, William B.; Department of Plant Sciences, University of Arizona, Tucson, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Experiments were conducted at the University of Arizona Safford and Maricopa Agricultural Centers during the 2001 cotton season to compare the effectiveness of 0.5 and 1.0 lb a.i./A topical applications of Buctril (bromoxynil) on annual morningglory species. At Safford, the percent control of annual morningglory was statistically greater following 1.0 lb a.i./A Buctril applications at 97 percent control compared to 83 percent control resulting from 0.5 lb a.i./A Buctril applications. Both the 0.5 and 1.0 lb a.i./A Buctril rates, had similar initial effects on morningglory seedlings. Initial leaf symptoms included a dark-green “water soaked” appearance that progressed into leaf necrosis. At both rates, all morninglory leaf tissue was destroyed leaving green stems which sometimes remained viable and produced new leaves rather than turning chlorotic and dying. The number of escapes in the center two rows of four-row plots was significantly greater after 0.5 lb a.i./A Buctril applications at 12.4 escapes compared to 1.5 escapes following 1.0 lb a.i./A Buctril applications. An average of 12 escapes in an area 40 ft by two cotton rows is sufficient to cause substantial yield losses in the absence of other control methods. At Maricopa, there was no statistically significant difference in the phytotoxicity caused by 0.5 and 1.0 lb a.i./A Buctril rates when applied to 1, 2, or 3 true-leaf exposed morningglory seedlings (i.e., not partially covered or shaded by other plants) that were thoroughly contacted by the herbicide sprays. Both experiments found that morningglory control was significantly greater following two sequential 0.5 lb a.i./A Buctril applications compared to a single 1.0 lb a.i./A application due to continued emergence of seedlings. Growers with morningglory infested fields that make a 1.0 lb a.i./A application should be prepared to make an early season post-direct application using other herbicides to control later emerging morningglory plants.
    • Six Years of Successful Management of Whitefly Resistance in Arizona Cotton

      Dennehy, Timothy; Zaborac, Marni; DeGain, Ben; Holley, Danny; Nicols, Robert; Li, Andrew Y.; Ellsworth, Peter; Palumbo, John; University of Arizona, Department of Entomology, Tucson, AZ; Cotton Incorporated, Cary, NC; et al. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Arizona cotton experienced a severe crisis in 1995 stemming from resistance of whiteflies to synergized pyrethroid insecticides. The insect growth regulators (IGRs) Knack® (pyriproxyfen) and Applaud® (buprofezin) served a pivotal role in resolving this problem. Statewide monitoring of whitefly resistance is conducted annually in Arizona to assess the status of resistance in this important pest. In this paper we provide an update on results from whitefly collections made from 19 cotton fields located throughout Arizona. Overall, whitefly control in Arizona cotton remained excellent in the 2001 season and there were no reported field failures. However, we detected major decreases in susceptibility to Knack of whiteflies collected from cotton. Whereas it was extremely rare to have any whiteflies surviving bioassays of 0.1 μg/ml from 1996 to 1998, this changed in 1999, and by the 2001 season over 60% of Arizona sites evaluated had •2% pyriproxyfen-resistant whiteflies. One collection from Eloy, Arizona, in 2000 had >50% of whiteflies surviving Knack bioassays of 0.1 μg/ml. Whiteflies throughout Arizona continued to be moderately less susceptible to Applaud, relative to susceptibility levels in 1996, when the IGRs were first introduced. In contrast to our findings with Knack, changes in susceptibility to Applaud have been only moderate and quantitative. Arizona whiteflies continued a six year trend of reduced resistance to synergized pyrethroid insecticides, as indicated by bioassays with mixtures of Danitol and Orthene. Problematic frequencies of whiteflies resistance to synergized pyrethroids were found at only two of 19 locations sampled. Steps should be taken now to prepare for the onset of more severe resistance to IGRs in Arizona cotton. Factors that could undermine the current success of whitefly resistance management in Arizona are discussed. Education efforts should reinforce the importance of limiting IGR use in cotton to a maximum of one treatment each per season and rotating conventional insecticides as recommended in the three-stage resistance management strategy implemented in 1996. Because Knack and Applaud have received registrations for use in Arizona vegetable and melon crops grown in proximity to cotton, it is now especially critical that Extension education efforts focus on cross-commodity coordination of IGR use recommendations to preserve the activity of these important insecticides.
    • Transgenic Comparisons of Pink Bollworm Efficacy and Response to Heat Stress

      Ellsworth, Peter C.; Moser, Hal; Henneberry, Tom; Majeau, Ghislane; Subramani, Jay; Maricopa Agricultural Center & Department of Entomology, University of Arizona, Maricopa, AZ; USDA-ARS, Western Cotton Research Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Fifteen lines from 3 different cotton families were compared. Each family had a conventional, non-transgenic standard, as well as 4 other transgenic lines. In some cases, near isogenic lines were available that theoretically only vary from their sibling lines in the presence or absence of one or more transgenes. Each Bt line was evaluated for this trait’s efficacy in controlling pink bollworm under high pressure, artificial infestations. Various agronomic properties were measured including yield, micronaire, ginning properties, and fiber quality. Heat tolerance, a key goal for Arizona adapted varieties, was also evaluated using a flower rating system. The Cry1Ac gene performed flawlessly in preventing PBW larval development when expressed alone (Bollgard®) or in combination with Cry2Ab (Bollgard II®) (i.e., 100% effective, 0 large larvae from 30185 PBW entry holes). In all cases where large larvae were found in Bollgard or Bollgard II plots, the plants bearing the infested bolls were not expressing the Cry1Ac toxin. Thus, those few times when larvae were found, it was due to contaminants in the seed supply. The novel Cry2Ab only expressing plants, produced for non-commercial testing purposes, were also very effective in controlling PBW large larval development; however, control was less than the Cry1Ac-expressing lines (99.622%, 3 large larvae from 4436 entry holes). The ramifications of this are discussed. In terms of agronomic performance, the transgenic lines performed similarly within families and usually not different from the conventional standards. In some cases, statistically different results were found; however, in all but a few cases, performance parameters were superior in the transgenic lines when compared to the conventional standard. Even so, there are instances where characteristics of the transgenic line were inferior to the conventional standard, especially in some fiber properties. Heat tolerance was again similar throughout 2 of the cotton families (SG125 and DP50). However, for the DP5415 family, 3 of the 4 transgenic lines outperformed the conventional standard. More testing under more environmental conditions is warranted before firm conclusions are drawn.
    • Evaluation of Manganese Fertility of Upland Cotton in the Lower Colorado Valley

      Silvertooth, J. C.; Galadima, A. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      A field experiments was conducted during the 2001 growing season to evaluate the effect of Manganese (Mn) fertility on growth, development, and yield of a commonly grown upland cotton variety in the Yuma Valley of Arizona. This project also provided an evaluation of the University of Arizona (UA) critical level for Mn fertility for cotton (1.0 ppm Mn). The study consisted of two treatments, which included an untreated control and a treatment receiving two foliar applications each of a pint of the product 3-0-0-27.4 using 18gal./acre carrier. Plant growth and development measurements, including estimates of fruit retention (FR) levels and height to node ratios (HNR’s) were similar for both treatments during the season. There was not a significant difference in lint yield between the control (untreated) and the treated plots. These results support the current UA Mn fertility guideline for cotton on not applying Mn when soil test levels exceed 1.0 ppm.
    • Yield, Quality, and Economic Comparison of Single and Double Seed Line Per Bed Cotton Production

      Husman, S. H.; McCloskey, W. B.; Teegerstrom, T.; Clay, P.; Norton, R.; White, K.; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Three experiments were conducted in Maricopa, Marana, and Glendale, Arizona in 2001 to measure cotton growth, yield, micronaire, and production costs in single and double seed line per bed systems on 32 and 40 inch beds. Canopy development was faster and canopy closure was greater in the double seed line than in the single seed line systems and was greater in the 32 inch than in the 40 inch row systems. At Maricopa, the single line 32 inch system yield of 1571 lbs./A was significantly greater than the yields of the other seed line/row spacing systems. The yields of the single line 40 and the double line 32 inch systems were not significantly different at 1476 and 1411 lbs. of lint/A, respectively, and the yields of the double line 32 and the double line 40 inch systems also were not significantly different at 1411 and 1396 lbs. of lint/A, respectively. There were no significant lint yield differences at the Marana or Glendale location. At Marana, the lint yields were 1063 and 1066 lbs./A for the single and double seed line 40 inch row spacing systems, respectively. At Glendale, the single and double seed line 38 inch row spacing systems yielded 1474 and 1551 lbs. of lint/A, respectively. In all 2001 experiments, there was a trend for reduced micronaire in the double seed line per bed systems compared to the single seed line per bed systems. At Maricopa, the average micronaire was 5.0 and 4.7 for the single and double seed line per bed 32 inch row system, respectively, and 5.2 and 4.9 for the single and double seed line per bed 40 inch row systems, respectively. At Marana, the micronaire was 4.7 and 4.5 for the single and double seed line per bed 40 inch row systems, respectively. At Glendale, the micronaire was 5.1 and 4.6 for the single and double seed line per bed 38 inch row systems, respectively. Production costs were similar for the single and double seed line per bed systems. Additional research will be conducted in 2002 to determine the optimum plant populations and in-row plant spacings for double seed line per bed production systems.