• 1997 Cottonseed Variety and Treatment Evaluation

      Knowles, Tim C.; Wakimoto, Del; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Three upland cotton varieties (Deltapine 5415, Stoneville 474, and SureGrow 125) were subjected to three seed treatments (non or control, standard commercial triple treated, and standard commercial plus Prevail added to the hopper box at 1 lb product /100 lb cottonseed) to determine seed germination and vigor in a Mohave Valley field prone to Rhizoctonia infection of cotton seedlings.
    • 1997 Low Desert Upland Cotton Advanced Strains Testing Program

      Husman, S. H.; Silvertooth, J. C.; Clark, L.; Nelson, J.; Knowles, T.; Wegener, R.; Johnson, K.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Upland cotton advanced strains and commercial check comparison varieties were evaluated in replicated field studies at five locations in 1997. The test sites include Parker, Az., Gila Bend, Az., Buckeye, Az., Maricopa, Az., and Safford, AZ. Ten seed companies submitted a maximum of five advanced strains entries. Three commercial check varieties were used at each site for comparison purposes and included DPL 5415, SG 125, and STV 474.
    • 1997 Season Update on Resistance of Arizona Whiteflies to Synergized Pyrethroid and Select Non-Pyrethroid Insecticides

      Dennehy, Timothy J.; Williams, Livey III; Li, Xiaohua; Wigert, Monika; Silvertooth, Jeff; Department of Entomology, The University of Arizona; Extension Arthropod Resistance Management Laboratory, Tucson, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      A whitefly resistance crisis in Arizona in 1995 prompted the development of a resistance management strategy in 1996 that recommended maximal once per season use of two insect growth regulators, pyriproxyfen (Knack®) and buprofezin (Applaud®), and limited and delayed use of synergized pyrethroid insecticides in cotton. Statewide monitoring of whitefly resistance has shown that implementation of this strategy has substantially reduced whitefly resistance to the synergized pyrethroids and has also resulted in increased susceptibility to key non pyrethroid insecticides. Having benefited from two years of success with this strategy, the Arizona cotton industry now faces the question of whether it can be sustained as pyriproxyfen and buprofezin gain additional registrations for use against whiteflies in vegetables, melons and glasshouse crops.
    • 1997 Seed Treatment Evaluations

      Norton, E. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Cottonseed was treated with several fungicide treatments in an effort to protect the seed and seedling from disease. Seed germination and vigor was evaluated in three Arizona locations; Maricopa, Marana, and Safford. Stand counts were taken on two separate dates after emergence at all three locations and percent emergence (PEM) was calculated. Significant differences in percent emergence due to treatment were observed in the both sample dates at Marana and Safford. Maricopa showed very little significant differences due treatment.
    • The 1998 Cotton Advisory Program

      Brown, P.; Russell, B.; Silvertooth, J.; Ellsworth, P.; Husman, S.; Knowles, T.; Clark, L.; Dunn, D.; Schneider, M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Arizona Cooperative Extension generates and distributes weather -based Planting Date and Cotton Development Advisories for 19 cotton production areas (Aguila, Buckeye, Cochise Co., Coolidge, Eloy, Greenlee, Co., Harquahala, Laveen, Litchfield Pk., Marana, Maricopa, Mohave Valley, Paloma, Parker, Pinal Co., Queen Creek, Roll, Safford and Yuma Valley). Planting Date Advisories are distributed from legal first planting date until the end of April and provide updates on heat-unit-based planting windows, recent and forecasted weather conditions, heat unit accumulations, variety selection, soil temperatures, recommended plant population, and early insect management and control. Cotton Development Advisories are distributed from early May through the end of August and provide updates on crop development, insects, weather and agronomy. The Cotton Advisory Program will continue in 1998, and growers may obtain advisories by mail/fax from local extension offices or by computer from the AZMET Internet Web Page (http://ag.arizona.edu/azmet) and AZMET Computer Bulletin Board System. Program changes planned for 1998 include 1) an expanded weather information update and 2) the addition of an advisory for the Buckeye area.
    • Aflatoxin Contamination of Bt and Non-Bt Cottonseed

      Knowles, Tim C.; Wakimoto, Vic; Wakimoto, Del; Keavy, Mike; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Transgenic Bt cotton varieties that are resistant to pink bollworm should sustain less feeding damage to bolls and cottonseed, compared to non-Bt varieties that are more susceptible to feeding damage by pink bollworm larvae. Prior to boll opening, the aflatoxin producing fungus Aspergillus flavus cannot penetrate undamaged cotton bolls. Thus resistance to pink bollworm could result in reduced aflatoxin contamination under high pink bollworm pressure. Cottonseed aflatoxin levels of Bt and non-Bt varieties were compared at various planting and harvest dates. Bt and non-Bt cotton varieties had similar cottonseed aflatoxin levels. Long season production systems favored high cottonseed aflatoxin levels, compared to short season production systems, regardles of the cotton variety grown.
    • Agronomic Evaluations of New Transgenic and Non Transgenic Cotton Varieties in La Paz and Mohave Counties

      Knowles, Tim C.; Wakimoto, Del; Sprawls, Greg; Hurtado, Greg; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      In 1996 transgenic Bt cotton was first grown on a commercial level in Arizona. In 1997 transgenic Roundup and Buctril herbicide resistant cotton varieties were introduced and grown on commercially in Arizona. Furthermore, in 1997, four new heat tolerant non- transgenic cotton varieties for commercial release in 1998 were available for University field tests. Prior to 1997, the agronomic characteristics of these new cotton varieties had not been evaluated inside by side replicated field comparisons beyond the level of the developing companies. Field tests were conducted in La Paz and Mohave Counties in 1997 examining agronomic characteristics of new transgenic Bt ( Deltapine 5415 vs. Deltapine 32 B and 33B) and herbicide resistant (Paymaster 1220 BGRR vs. 1244 BGRR and Stoneville 474 vs. BXN 47) and non transgenic heat tolerant (SureGrow 125 vs. 180 and 821, Stoneville 474 vs. 468, and Germain's GC 9230) cotton varieties.
    • Agronomic Evaluations of Transgenic Cotton Varieties

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Several field experiments were conducted in many of the cotton growing areas of Arizona in 1997 for the purpose of evaluating agronomic characteristics of many new transgenic Upland cotton varietie. In many cases, the new transgenic lines were compared directly with their recurrent (non-transgenic) parents. Evaluations were carried out by collecting plant mapping data from each variety on a regular 14 day interval throughout the season and relating the resultant information to established baselines for Upland cotton in Arizona. Lint yield measurements were also taken on each variety at all locations. Results indicate that all transgenic lines tested are very similar to their recurrent parents in terms of growth, development, and yield Some subtle differences were noted but they were very slight and should impact management of the varieties significantly in comparison to their recurrent parents.
    • Arizona Upland Cotton Variety Testing Program, 1997

      Silvertooth, J.; Norton, R.; Clark, L.; Husman, S.; Knowles, T.; Gibson, R.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Eleven field experiments were conducted in major cotton growing areas of Arizona in 1997 for the purpose of evaluating Upland cotton varieties in terms of adaptability and performance. Six commercial cottonseed companies participated in the program. A maximum of two varieties were submitted by each company at each location. Experiments were conducted on a commercial level on grower-cooperator fields in most cases. Locations used in the program spanned the range of conditions common to cotton producing areas of the state from about 100 ft. to 4,000 ft. elevation. Results indicated a broad range of adaptability and competitiveness. Each of the participating seed companies offer a compliment of varieties that can serve to match various production strategies commonly employed in the state. Many varieties commercially available performed well at several locations demonstrating good adaptation to Arizona conditions.
    • Can Resistance to Chloronicotynl Insecticides be Averted in Arizona Field Crops?

      Williams, Livy III; Denney, Timothy J.; Palumbo, John C.; Silvertooth, Jeff; Department of Entomology, The University of Arizona; Extension Arthropod Resistance Management Laboratory, Tucson, AZ; Yuma Agricultural Center, Yuma, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      A resistance management program was initiated in Arizona in 1995, the initial goal of which was to sustain the efficacy of imidacloprid (Admire®) against Bemisia in vegetable crops. Due to the anticipated registration of additional chloronicotinyl (and related neonicotinyl) insecticides in Arizona, project objectives were subsequently broadened to address management of this entire class of insecticides in Arizona field crops. Results from three years of statewide monitoring of whiteflies from cotton indicated that whitefly populations in Arizona have become significantly less susceptible to imidacloprid in each of the past two years and significant geographical differences were described. However, no evidence was found of reduced field performance of imidacloprid in vegetables. Additionally, laboratory studies subjecting Arizona whiteflies to selection with imidacloprid did not increase levels of resistance beyond those occurring in the field. A study exploring the influence of cropping system differences on imidacloprid use (Admire® and Provado®) revealed no major differences in susceptibility to this insecticide between populations of whiteflies in central and southwestern Arizona. However, distinct seasonal shifts to lower susceptibility from 1996 to 1997 were observed in the Dome Valley of southwestern Arizona. Susceptibility of Arizona whitefly populations to imidacloprid was highly correlated with susceptibility to acetamiprid but was unrelated to susceptibility to CGA-293343. There is an urgent need to harmonize chemical use and resistance management efforts in Arizona cotton, vegetables and melons to avoid conflicts resulting from movement of pests between crops.
    • Comparison of the Two Methods for the Analysis of Petiole Nitrate Nitrogen Concentration in Irrigated Cotton

      Smith, J. H.; Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      A study was conducted in Arizona in 1997 with the objective of analyzing the accuracy of a recently developed portable nitrate meter (Cardy meter) to effectively measure petiole nitrate - nitrogen (NO₃-N) in irrigated cotton (Gossvpium sue.). This task was accomplished by performing correlation and linear regression analyses on NO₃-N concentrations of cotton petiole sap, as measured by the Cardy meter, against the standard procedure NO₃-N analysis, as measured by an ion selective electrode (ISE). Results revealed that the NO₃-N concentrations of petiole sap were highly correlated with dried petiole NO₃-N (pearson correlation coefficient = 0.96, P < 0.0001). A regression equation with an r² = 0.92 was derived: Y = 9.96X - 1170.86, where X and Y are NO₃-N in petiole sap (ppm) and dried petioles (ppm), respectively. These results suggest that the sap analysis using the Cardy meter is a potentially valuable tool to monitor the in-season N status of irrigated cotton.
    • Correlation between Early Season Insecticide Control of Pink Bollworm and Other Pests and Subsequent Whitefly Applications near Gila Bend, AZ, 1997

      Jech, L. E.; Husman, S. H.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Cotton pesticide application histories in the Gila Basin were followed from 27 April through 20 September. The main interest was the effect of early season applications to control pink bollworm, Pectinophora gossypiella, and other pests on subsequent whitefly applications. Categories explored include, transgenic and non transgenic cotton, planting dates, and location within the valley. Regression analysis shows a significant effect due to the early season control for either P. gossypiella, or other pests (P > 0.009) but lower for them together (P > 0.026). Early applications for either PBW or other pest resulted in increased application for whitefly.
    • Cotton Defoliation Evaluations, 1997

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Three field experiments were conducted near Yuma, Coolidge, and Marana, AZ in 1997 to evaluate the effectiveness of a number of defoliation treatments on Upland (var. DP NuCotn 33b) cotton. All treatments consisted of materials commercially available in Arizona. Results reinforce general recommendations regarding the use of low rates (relative to the label ranges) under warm weather conditions and increasing rates as temperatures cool.
    • Cotton Virus Diseases

      Nelson, M. R.; Nadeem, A.; Ahmed, W.; Orum, T. V.; Silvertooth, Jeff; Department of Plant Pathology, University of Arizona, Tucson, AZ; Central Cotton Research Institute(CCRI), Multan Pakistan; Ayub Agricultural Research Institute(AARI), Faiselabad, Pakistan (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Virus diseases of cotton have historically been of only sporadic importance to global cotton production. Recent devastating epidemics in Pakistan and other areas have brought new awareness to the potential for disaster of a pathogen once considered to be of a minor importance. Under changing conditions this pathogen (cotton leaf curl virus) has emerged as a serious problem in Pakistan and India. Cotton leaf curl virus does not occur in the United States or the rest of the western hemisphere but recent experience worldwide is a reminder that pathogens, such as this geminivirus, can be moved easily from one part of the world to another and therefor we need to be aware of the potential impact of such pathogens on local crops.
    • Date of Planting by Long Staple and Short Staple Variety Trial, Safford Agricultural Center, 1997

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Four varieties each of Long Staple and Short Staple cotton were tested over five and four dates of planting, respectively, in this study. The first date of planting for the Long Staple cotton was pushed up to the 18th of March because planting is now legal in Graham county as early as March 15th. The latest planting was May 13th. Cultivars of differing maturities were tested for both long and short staple cotton to determine their optimal planting time. Many agronomic and hvi values were evaluated to determine the effect of different planting dates
    • Defoliation of Pima and Upland Cotton at the Safford Agricultural Center, 1997

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Nine defoliation treatments were applied to Pima and upland cotton to compare the treatment effects on percent leaf drop and percent green leaves left and any effects they might have on yield or fiber qualities. All of the treatments were beneficial compared to the untreated check, the treatments including Ginstar performed better than those without.
    • Defoliation Tests with Ginstar at the Maricopa Agricultural Center in 1997

      Nelson, John M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Defoliation tests were conducted on Upland and Pima cotton at the Maricopa Agricultural Center to evaluate rates of Ginstar, tank mixes of Ginstar with other defoliants and Ginstar used as a preconditioner. The cotton used in these tests was generally difficult to defoliate, probably because of an excessive supply of nitrogen and cool temperatures in October and November. In early October, only the Ginstar + Def treatment gave good defoliation of upland while all treatments gave good defoliation of Pima cotton. In late October tests, temperatures were cool and only Ginstar + Def and Ginstar followed by Ginstar treatments gave effective defoliation in 14 days. In October and November tests, Ginstar used as a preconditioner was effective in helping to defoliate cotton under, cool weather conditions.
    • Development of a Yield Projection Technique for Arizona Cotton

      Norton, E. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      A series of boll measurements were taken at numerous locations across the state in 1997 in an attempt to continue to develop a yield prediction model that began in 1993. Results from 1995 showed the strongest relationship between final open boll counts and yield. Based on these results, data was collected in 1997 from several locations around the state. Boll counts were made just prior to harvest and then correlated to yield. Results showed that a good estimate for lint yield could be obtained using the factor of approximately 13 bolls/row-ft./bale of lint for Upland cotton on 38 to 40 inch row spacings.
    • Diversity and Global Distribution of Whitefly-Transmitted Geminiviruses of Cotton

      Brown, J. K.; Silvertooth, Jeff; Department of Plant Sciences (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Geminivirus diseases of cotton are on the rise, worldwide, yet few have been studied in adequate detail to permit the implementation of rational approaches to disease control. The rising costs of managing the whitefly vector, coupled with substantial losses caused by geminivirus-incited diseases now hinder cotton production by requiring inputs that are beyond economic feasibility. The need for geminivirus disease resistant cultivars in diverse cotton producting areas and against different viral genotypes presents a new challenge. To meet this need, information about the identity, distribution, and relevant biotic characteristics of cotton -infecting geminiviruses is needed This project addresses this problem through the molecular analysis of the genomes of cotton-infecting geminivirus from cotton throughout the world Here, sequence similarities of the coat protein gene and of the non-coding IR/CR involved in regulating virus replication and transcription were examined by comparative sequence analysis to achieve virus identification. This is the first effort to determine virus identity and to map the distribution of geminiviruses on a global basis. The outcome of this effort will be a data base containing biotic and molecular information that will permit rapid and accurate geminivirus identification, and the selection of relevant viral species for development of cotton cultivars with disease resistance to the geminiviruses specific to individual production areas.
    • Do PIX® Application Guidelines Change for Bt Cotton?

      Husman, Stephen H.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Two PIX experiments were conducted on commercial cooperator sites in Waddell and Buckeye, Az in 1997 to evaluate the validity of the published University of Arizona (UA) PIX application guidelines for Bt cotton. Experimental treatments consisted of an untreated check, a calendar based application schedule (early bloom, peak bloom, cutout), and a feedback approach using plant growth measurements based on the UA PIX guidelines (height:node ratio, fruit retention). There were no significant yield differences at the Waddell site where height:node ratios and fruit retention values were above the optimum baseline season long, conditions not supportive of PIX applications. There was a significant yield decline at the Buckeye site between the untreated check and the calendar based treatment. Due to low plant vigor season long , there were no feedback based PIX applications. PIX applications under low vigor conditions can further compromise plant vigor and ultimately yield. The UA PIX application use guidelines are valid and should be used for both Bt and non -transgenic Upland cotton varieties.