• 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; USDA-ARS, U.S. Livestock Research Laboratory, Kerrville, TX; University of Arizona, Department of Entomology, Maricopa, AZ; University of Arizona, Department of Entomology, Yuma, AZ (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.
    • 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.
    • Defoliation of Pima and Upland Cotton at the Safford Agricultural Center, 2001

      Clark, L. J.; Coleman, R. D.; Carpenter, E. W.; Norton, E. R. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Nine defoliation treatments based on standard and reduced rates of Ginstar and Chlorate plus two additives (compounds F and S) were applied to Pima and Upland cotton to compare the treatment effects on percent leaf drop and yields. All of the treatments were beneficial to leaf drop compared to the untreated check with the Ginstar treatments generally performing better than the Chlorate. Both of the additives enhanced the early defoliation effectiveness for the reduced rates of Chlorate and Ginstar over all other treatments, including the full rates of the Chlorate and Ginstar. Generally, this same enhanced effectiveness was seen of the additives plus reduced rates over the full rates of Chlorate and Ginstar throughout the defoliation process. This is the second year of the study.
    • Evaluation of Irrigation Termination Effects on Fiber Micronaire and Yield of Upland Cotton, 2001-2002

      Silvertooth, J. C.; Galadima, J. (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 that irrigation termination management can impact fiber micronaire. Field studies were conducted in 2000 and 2001 at the University of Arizona Maricopa Agricultural Center (MAC; 1,175 ft. elevation) and the Yuma Valley Agricultural Center (YVAC; 150 ft. elevation) to evaluate the effects of three dates of irrigation termination on the yield of several Upland cotton varieties. Three dates of irrigation termination (IT1, IT2, and IT3) were imposed based upon crop development. 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 provided one additional irrigation over an optimal point for the first cycle fruit set and two irrigations beyond IT1. The final (IT3) date (later September) was staged so that soil moisture would be sufficient for the development of a full top-crop potential. Lint yield and micronaire results have consistently revealed significant differences among the IT treatments. The micronaire values were consistently less than 5.0 for the IT1 treatments. Micronaire and lint yield values increased with later IT dates.
    • 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.
    • Pink Bollworm and Cabbage Looper Motalities and NuCOTN 33B (Bt) Cry1Ac Contents in Cotton Fruiting Forms and Leaves on Increasing Numbers of Days after Planning

      Henneberry, T. J.; Forlow Jech, 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)
      Studies were conducted to follow seasonal susceptibility of feral pink bollworm (PBW), Pectinophora gossypiella (Saunders) larvae to NuCOTN 33B (Bt) and Deltapine (DPL) 5414 in furrow and furrow plus supplementary drip-irrigated cotton field plots. Laboratory bioassays of laboratory - reared PBW larvae to flower buds and bolls and cabbage looper (CL), Trichoplusia ni (Hübner), larval mortality feeding on DPL 5415 and Bt cottons leaves were also conducted. Cry1Ac insect toxic protein contents in the different plant tissue were determined by Enzyme Linked ImmunoSorbent Assay (ELISA) throughout the season to compare in relation to PBW and CL mortality data. Irrigation type had no effect on PBW or CL larval mortality parameters measured. DPL 5415 bolls had 0.15 feral live larvae per boll and no dead larvae per boll compared with no live and 0.12 dead feral larvae per Bt boll. Whole plant samples showed 0.5 to 8.6% live larvae boll infestations compared to no live PBW life stages and no exit holes for Bt bolls. No PBW larvae survived on day four following bioassay infestation of one-third grown Bt flower buds with PBW neonate larvae as compared to 90% larval survival on DPL 5415 flower buds. Immature bolls harvested in the field and artificially infested with PBW larvae in the laboratory showed averages of 3 to 52% live larvae per boll, all in fourth instar of development, for DPL 5415 bolls compared to no live larvae, no development beyond the first instar, and no exit holes for Bt bolls. Cry1Ac protein level in flower buds were 0.11 to 0.16 ppm and 0.14, 0.11 and 0.05 ppm, in each case, per wet weight gram of boll tissue in bolls during the season. For CL leaf bioassays, larval mortalities after 7 days feeding on Bt leaves were variable ranging from 82 to 94% from node 8 on 61 and 82 days after planting (DAP) to 32, 38 and 7% on leaves from node 16 on 82, 117, and 159 DAP, respectively, and 28 and 6% on leaves from node 24 on 117 and 159 DAP. Cry1Ac amounts were 0.96 and 0.85 ppm (wet wgt per g of Bt leaf tissue), from leaves from node 8 (61 and 82 DAP), 0.53, 0.50 and 0.22 ppm (node 16, 82, 117, and 159 DAP) and 0.44 and 0.18 ppm (node 24, 117 and 159 DAP). Numbers of cotton bolls, lint and seed per acre were significantly greater from plots that were furrow plus drip irrigated as compared to furrow irrigated alone. DPL 5415 and Bt cotton yields were not significantly different.
    • Susceptibility of Arizona Pink Bollworm to Cry1Ac

      Sims, Maria A.; Dennehy, Timothy J.; Shriver, Laura; Holley, Danny; Carrière, Yves; Tabashnik, Bruce; Antilla, Larry; Whitlow, Mike; Department of Entomology, University of Arizona, Tucson, AZ; Arizona Cotton Research and Protection Council, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Genetically modified cotton expressing the Cry1Ac toxin has been used in Arizona since 1996 with exceptionally positive results in terms of economic returns to growers and reductions in insecticide use in cotton. Since 1995, average insecticide use in Arizona cotton has declined from greater than six applications per acre to less than two in 2000. Bt cotton has contributed greatly to these savings to growers, as have insect growth regulators used for whitefly control. Collections of pink bollworm, Pectinophora gossypiella, made in 1997 and subsequently exposed to Cry1Ac in the laboratory from 1998 to 2000, yielded a laboratory strain with susceptibility to Cry1Ac reduced 1,000 to 3,000- fold, relative to highly susceptible field populations. Unparalleled measures have been taken to detect and manage this resistance. In this report we summarize results of statewide monitoring of pink bollworm susceptibility to Cry1Ac conducted from 1997 to 2000, and results of field evaluations of the effectiveness of Bt cotton from 1995 to 2001. Susceptibility of Arizona pink bollworm to Cry1Ac, increased from 1997 to 2000. Mean corrected mortality in 1μg/ml Cry1Ac assays was 57.4% in 1997, 90.6% in 1998, 97.9% in 1999 and 97.4% in 2000. Mean corrected mortality in bioassays of 10 μg/ml also increased: it was 94.1% in 1997, 99.9% in 1998, 100% in 1999 and 100 % in 2000. Field performance of Bt cotton in 2000 continued to be excellent at 39 locations throughout Arizona cotton at which paired Bt and non-Bt fields were evaluated. Whereas non-Bt cotton fields had mean infestations of over 15% infested bolls, Bt cotton fields averaged less than 0.15% infested bolls. Thus, after six years of intensive use of Bt cotton in Arizona, pink bollworm populations show no signs of being resistant to Bollgard cotton. Indeed, for reasons that are not understood at this time, they have been found to be significantly more susceptible to the Bt toxin in Bollgard cotton at the end of the 2000 season than they were in 1997.
    • Pink Bollworm: Diapause Larval Exit from Harvested Immature Cotton Bolls and Percentages Surviving to Moth Emergence

      Henneberry, T. J.; Forlow Jech, L.; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      Pink bollworm (PBW), Pectinophora gossypiella (Saunders), diapause larval exit from immature green bolls and larval and pupal mortality after exiting bolls, were studied at Phoenix, AZ in the insectary. Diapause larvae exited immature bolls sporadically during January, February, and early March. Thereafter, exit from the bolls was more consistent and highest numbers emerged in late April, May or early June. Larval and pupal mortality were high during January to early February and March, decreased in mid-March through early June, and increased again in mid-June to early August. Larvae remained in immature bolls as long as 319 days after harvest. Moth emergence was significantly correlated to accumulated heat units (12.8 and 30.6°C lower and upper developmental thresholds).
    • 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.
    • 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.
    • 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.
    • 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.
    • 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.
    • Review of the 2001 Arizona Cotton Season

      Silvertooth, Jeffrey C. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
    • 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.
    • 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.
    • 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.
    • 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.
    • Upland Cotton Variety Evaluation in Graham County

      Norton, E. R.; Clark, L. J. (College of Agriculture, University of Arizona (Tucson, AZ), 2002-06)
      A field trial was established during the 2001 growing season as part of the statewide Upland Cotton Variety Testing Program. This trial was located in Thatcher with Dennis Layton Farms as the cooperator. The location was one of eleven around the state. Seven Upland cotton varieties to be evaluated at this location were entered by various cooperating seed companies. A new variety from FiberMax produced the highest yield and also possessed the highest quality fiber making it the variety that would have produced the highest gross income to the producer.