• Contrasts of Three Insecticides Resistance Monitoring Methods for Whitefly

      Simmons, A. L.; Dennehy, T. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Three resistance monitoring methods were tested to evaluate their relative reliability, discriminating ability, convenience, and practicality for monitoring insecticide resistance in Arizona whiteflies. Adult whiteflies were collected from the field and tested in the laboratory with three methods: leaf disk, sticky trap, and vial. Each method was evaluated against two populations divergent in susceptibility using a mixture of Danitol® + Orthene® and two single chemicals, Thiodan® and Danitol®. The Yuma population was relatively susceptible and the Gila River Basin population highly resistant. Correlations of field efficacy and leaf disk bioassays were conducted with the Yuma population and a comparatively resistant Maricopa population. At each location egg, immature, and adult whitefly densities were monitored before and after Danitol® + Orthene® treatments and resistance estimates were also monitored in the populations using leaf disk bioassays. Our results illustrated that the leaf disk method had the greatest discriminating ability between susceptible and resistant populations. The results also indicated that the vial method was the most practical, and that the sticky trap method was good at discriminating between populations that have large differences in susceptibility. The field efficacy trials indicated results from leaf disk assays reflected what had occurred in the field.
    • Low Desert Upland Cotton Advanced Strains Testing Program, 1995

      Husman, S. H.; Jeck, L. E.; Metzler, F.; Wegener, R.; Killian, K.; Stephens, L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Twenty one Upland cotton advanced strains varieties which are not commercially available were evaluated in replicated field studies in 1995 on two farm sites in Queen Creek, Arizona and Buckeye, Arizona representing seven seed companies. Twenty four advanced strains representing eight seed companies were evaluated on a commercial site in Gila Bend, Arizona. Participating seed companies submitted three advanced strain entries, plus a commercially available check of their choice at each site. The Gila Bend site represented strains of a more indeterminate nature for a full season production approach, while the sites at Buckeye and Queen Creek consisted of more determinate entry characteristics to represent a reduced season production approach. The highest lint yields were obtained from Germains 9230 (1756 lb./a), Delta and Pine Land Co. 5517 (1116 lb./a), and Delta and Pine Land Co. 9057 (1578 lb./a) at Queen Creek, Buckeye, and Gila Bend respectively.
    • Response of Cotton to Precision-Guided Cultivation and DSMA in a Dense Stand of Purple Nutsedge

      Thacker, Gary W.; McCloskey, William B.; Silvertooth, Jeff; UA Cooperative Extension, Pima County, Tucson, Arizona; Department of Plant Sciences, University of Arizona, Tucson, Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Close cultivation (within 1.5 inches of the cotton drill row) accomplished with an electro-hydraulic machine guidance system and an early season application of the herbicide DSMA were evaluated for purple nutsedge suppression in cotton. There were no significant differences in the cotton plant mapping data collected mid - season except that there was significantly less boll retention on the second fruiting branch in the precision cultivator treatments that may have been caused by root pruning during the second precision cultivation that could have shocked the cotton. There were significant differences in seed cotton yield with the precision cultivator treatments yielding more than the standard cultivator treatments. There was an opposing yield trend with the use of DSMA; DSMA tending to be beneficial with the precision cultivator and detrimental with the standard cultivator. We cannot explain this opposing trend. We regard our results as preliminary until we gain more experience with precision-guided cultivators in dense stands of nutsedge.
    • Short Staple Cotton Advanced Strains Trial, Safford Agricultural Center, 1995

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Sixteen short staple advanced strains/varieties were grown in a replicated field on the Safford Agricultural Center in 1995. These included entries from ChemBred, Delta Pine, Sure-Grow, Olvey and Associates, McDaniels, NMSU and Australia. The Australian materials produced quite well with three of the entries placing in the top four with respect to lint yield. The highest yielding cultivar being an Australian entry, A83203-183, with a yield of 1508.5 pounds of lint per acre. In addition to yield data, this report includes many agronomic parameters including seedling vigor index, height to node ratio, and boll size. HVI analyses are also included in the report.
    • Effect of Norflurazon (Zorial Rapid 80®) Mixed with Pendimethalin (Prowl®) and Prometryn (Caparol®) on Cotton Stand Establishment and Yield

      McCloskey, William B.; Dixon, Gary L.; Silvertooth, Jeff; Department of Plant Sciences, University of Arizona, Tucson, Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      The effect on cotton stand establishment and seed cotton yield of various rates of norflurazon applied in combination with pendimethalin or both pendimethalin and prometryn was determined in field studies conducted at the Maricopa Agricultural Center in 1994 and 1995 in a sandy loam soil. Cotton stand counts were highest when only pendimethalin was applied or when no herbicide was used. Tank mixing prometryn with pendimethalin did not significantly reduce plant populations. Tank mixing increasing amounts of norflurazon with pendimethalin resulted in decreasing plant populations in both the wet and the dry plant experiments. Tank mixing increasing rates of norflurazon with both pendimethalin and prometryn caused a similar decline in plant populations in both the wet and the dry plant experiments. The symptoms of dying cotton seedlings and the stand count data indicated that notflurazon was the component of the tank mixtures that caused seedling mortality. The effect of the herbicide treatments on seed cotton yields was much less than on stand counts, but the same trends discussed above were evident. However, at the label rate for norflurazon in coarse textured soils, 0.5 lb a. i./A, seed cotton yields were not significantly reduced. The smaller effect of the herbicide treatments on seed cotton yields was due to the bush type nature of DPL 5415 and increased growth of surviving plants when plant populations were reduced. The data indicates that yield losses were not significant unless plant populations were reduced below about 20,000 to 25,000 plants /A.
    • Comparison of Various Plant Growth Regulators on Pima S-7 Cotton Yields

      Rethwisch, Michael D.; Hurtado, Greg; Hurtado, Rosario; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      All plant growth regulators and nutritional products applied to Pima S-7 cotton during bloom economically increased lint yields, with increases ranging from 80 - 261 lbs. /acre. Greatest increase was noted with Boll-Set Plus, a product that contains raised levels of calcium and zinc. Cytokin and Boll -Set Plus significantly increased yields at one location. A lint yield increase of approximately 40 lbs/acre was noted when Tech-Flo Alpha was added to Cytokin. A single application of Foliar Triggrr resulted in equal yields as two applications of the Cytokin plus Tech-Flo Alpha.
    • Cultural Control and Pink Bollworm Populations

      Chu, C. C.; Henneberry, T. J.; Silvertooth, Jeff; USDA, ARS, Western Cotton Research Laboratory, Phoenix, Arizona 85040-8830 (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      A cotton management program in the Imperial Valley, CA was designed to reduce pink bollworm, Pectinophora gossypiella (Saunders), populations. The program established I March as the earliest planting date, 1 September for defoliant or plant growth regulator application and 1 November for cotton stalk destruction and plowdown. In-season gossyplure-baited pink bollworm male moth activity monitoring and immature green cotton boll inspections for larval infestation were encouraged as decision making aids to determine the need for additional control action. Male pink bollworm moth catches in gossyplure-baited Lingren and delta sticky traps were significantly reduced each year from 1990 to 1994 following the initiation of the management program in 1989. Fewer larvae per cotton boll occurred in the years from 1990 to 1992. Fiber quality of commercial cotton sampled was also improved from 1989 to 1994, as compared to the 1984 to 1988 average. Cotton production, in general, was reduced during 1989 to 1994 in areas surrounding Imperial Valley and may have contributed partially to reduced populations in Imperial Valley.
    • Monitoring and Management of Whitefly Resistance to Insecticides in Arizona

      Dennehy, T. J.; Williams, Livy III; Russell, June S.; Li, Xiaohua; Wigert, Monika; Silvertooth, Jeff; Extension Arthropod Resistance Management Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Monitoring of whitefly resistance in the major cotton producing areas of Arizona confirmed the presence of an over 100 fold resistance to the mixture of Danitol® + Orthenem (fepropathrin + acephate). Strong evidence was found of cross-resistance affecting the other principle pyrethroid insecticides used to control whiteflies (Asana®, Capture® Karate®). Susceptibility to Ovasyn® varied widely in leaf -disk bioassays; lesser variation was observed in whitefly susceptibility to endosulfan. A provisional resistance management strategy (IRM) for Arizona whiteflies was formulated and evaluated in a 200 acre field trial in 1995. A key element of the strategy was diversifying as much as possible the insecticides used against whiteflies. Contrasts of this (rotation) strategy with a more conventional (less diverse) regime showed that rotation slowed but did not prevent resistance from developing. By seasons end both the IRM and conventional plots had very high and comparable levels of resistance to Danitol® + Ortliene®. This large field trial illustrated clearly the seriousness of the whitefly resistance problems faced in Arizona. It showed that whitefly populations cannot be managed effectively solely with the products currently registered for this purpose in Arizona. The large shift to lower susceptibility took place with as few as 3 insecticide treatments. In concert, our field art laboratory results indicated unequivocally that Arizona growers will be forced by resistance to greatly reduce reliance on pyrethroid insecticides in the future. This underscores the urgency for obtaining approval of novel new insecticides for whitefly control and for deploying new products within the framework of a resistance management strategy that limits their use.
    • Potassium Fertilization of Pima and Upland Cotton at Three Arizona Locations

      Galadima, A.; Silvertooth, J. C.; Norton, E. R.; Husman, S. H.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Three field trials were conducted in Arizona in 1995 at three locations (Safford, Maricopa and Buckeye) to evaluate yield benefits associated with potassium (K) fertilization. The 1995 and previous years studies were aimed at assessing the agronomic necessity of K fertilization in Arizona cotton (Gossvpium spp.) production. At the Safford Agriculture center (Pima clay loam), both Upland (G hirsutum L., var. DPL 90) and Pima (G. barbadense L., var. S-7) cotton included treatments of both soil and foliar K applications. The trial at Maricopa Agricultural Center (Casa Grande sandy loam) included four foliar K applications over the growing season on Pima (G barbadense L., var. S-7) cotton. The third trial was at the Buckeye location (Superstition silty loam) where a single foliar application over split plots preceded by soil application on Pima (G. barbadense L, var. S-7) cotton was undertaken. The results of the experiments at the Safford and Maricopa locations indicated no lint yield responses to K fertilization by either Upland or Pima cotton; however, at the Buckeye location, the result indicated a significant difference between the means of the soil-only and the soil-plus-foliar treatments. There were however no significant differences among soil-only treatments as well as the soil-plus-foliar treated plots when compared to their respective controls.
    • The 1996 Arizona Cotton Advisory Program

      Brown, P.; Rusell, B.; Silvertooth, J.; Ellsworth, P.; Stedman, S.; Thacker, G.; Husman, S.; Cluff, R.; Howell, D.; Winans, S.; et al. (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Arizona Cooperative Extension generates and distributes weather -based Planting Date and Cotton Development Advisories for 14 cotton production areas (Marana, Laveen, Paloma, Litchfield Pk., Pinal Co., Parker, Mohave Valley, Queen Creek, Safford, Yuma Valley, Aguila, Cochise Co., Greenlee Co. and Harquahala). Planting Date Advisories are distributed from mid -February through the end of April and stress 1) planting cotton varieties according to heat unit accumulations rather than calendar date and 2) the importance of soil temperature to good germination. Cotton Development Advisories are distributed from early May through mid - September and provide updates on crop development, insects, weather and agronomy. The Cotton Advisory Program will continue in 1996 and growers may obtain advisories by mail or fax from the local county extension office, and by computer from AZMET or the University of Arizona College of Agriculture World Wide Web Page. Major program changes planned for 1996 include 1) adjusting the Crop Development Advisories to reflect the revised legal first planting dates in low elevation production areas and 2) the addition of an advisory for Harquahala.
    • Tillage Energy Savings from Zone Burial of Shredded and Whole Cotton Stalks

      Carter, Lyle; Chesson, Joe; Thacker, Gary; Penner, Vic; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Two prototypes of a stalk burial implement were tested for energy requirements at the University of California, Shaffer Research Station. Both versions of the implement are designed to bury the cotton stalks in a concentrated zone and reform the bed in the same location. To plow under shredded stalks, both versions of the implement required less energy than a conventional tillage systems typical of the San Joaquin Valley of California. Both stalk burial implements were also used to plow under whole cotton stalks. This offers additional energy savings by eliminating the stalk shredding operation.
    • Pima Variety Test, Marana, 1995

      Thacker, G.; Norton, R.; Silvertooth, J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Four Pima varieties were grown in a replicated trail on the Evco Farm in Marana. There were no significant differences in lint yield.
    • Evaluation of Soil Conditioners and Water Treatments for Cotton Production Systems

      Silvertooth, J. C.; Sanchez, C. A.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Advanced technologies to produce synthetic polymers such as polyacrylamide (PAM, and polymaleic anhydride (PMA) have produced products which may be economically feasible alternatives to traditional treatments such as gypsum in the desert Southwest. In 1995 a single field study was conducted at Paloma Ranch, west of Gila Bend in Maricopa County Arizona Upland Nucoton 35, DPL' was dry planted and watered -up on 10 and 11 April. Treatments consisted of various rates and times of applications of Sper Sal™, which included a check (no Sper Sal), 1 and 2 qts. /acre with the water-up irrigation; 1 and 2 qts./acre with a mid - season irrigation; and 1 qt. /acre mid-season following 1 or 2 qts./acre with the water -up irrigation. No differences among treatments were detected among any treatments in terms of plant growth and development or final lint yields. There were no early-season differences in soil crusting among the various soil amendment treatments in 1995, as opposed to 1994 when a severe rain occurred immediately following planting.
    • Chemical Control Studies of Silverleaf Whitefly Control

      Chu, C. C.; Henneberry, T. J.; Silvertooth, Jeff; USDA, ARS, Western Cotton Research Laboratory, Phoenix, Arizona 85040 -8830 (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Chemical control studies for silverleaf whitefly, Bemisia argentifolii Bellows and Perring, control on cotton showed that fenpropathrin-acephate, fenpropathrin-endosulfan, and endosulfan-bifenthrin mixtures gave adequate control and increased cotton yields were obtained as compared within untreated cottons. Pyriproxyfen, applied biweekly or alternated with fenpropathrin-acephate, Nicotiana, and a fenpropathrin-mycotrol mixture also gave effective control.
    • Pima Cotton Regional Variety Trial, Safford Agricultural Center, 1995

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Eighteen 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 1995 was OA 312 (Conquistador) with a yield of 937 pounds of lint per acre. It was followed by OA 304 the high yielding variety from the year before and three other Olvey varieties and Phytogen 57. The average yield from this trial was nearly 100 pounds per acre higher than the previous trial Yield and other agronomic data as well as fiber quality data are contained in this paper.
    • Pima Regional Variety Test at the Maricopa Agricultural Center, 1995

      Hart, G. L.; Nelson, J. M.; Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Eighteen Pima varieties and experimental strains were grown in a replicated trial at the Maricopa Agricultural Center. Lint yield, boll size, lint percent, plant population, plant height and fiber property data are presented in this report.
    • Magnitude and Strain Composition of Aspergillus flavus Soil Surface Populations in Yuma County Commerical Fields

      Nelson, M. R.; Bigelow, D. M.; Orum, T. V.; Howell, D. R.; Cotty, P. J.; Silvertooth, Jeff; Department of Plant Pathology, University of Arizona, Tucson; Cooperative Extension Service, University of Arizona; Southern Regional Research Center, USDA, ARS (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Aflatoxin contamination of cottonseed occurs when cotton bolls are infected by certain strains of the fungus Aspergillus flavus. The risk of aflatoxin contamination in a field is partially dependent on both the quantity of A. flavus and the toxigenicity of A. flavus strains in that field. A. flavus can be easily divided into two major subdivisions known as strain S and strain L. Strain S isolates consistently produce large amounts of aflatoxin and, therefore, the percentage of strain S isolates in the population (percent S) is one indication of the aflatoxin producing potential of the population. Strain S isolates were found in every commercial field sampled at every sampling date in Yuma County, but percent S varied greatly among fields from 4% to 93 %. Significant differences among fields located near each other suggest that locally important, but not yet identified, variables such as crop rotation histories or soil type are affecting A. flavus population magnitude and composition.
    • Fenoxycarb, Pymetrozine (C G A-215944), and Fenpropathrin/Acephate: Rotations for Silverleaf Whitefly Control in Upland Cotton in Central America

      Akey, D. H.; Henneberry, T. J.; Silvertooth, Jeff; USDA, ARS, Western Cotton Research Laboratory, 4135 East Broadway, Phoenix, Arizona 85040 -8830 (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Trials (0.01 ac plots) with fenoxycarb ( Fenoxycarb 40 W P, 0.0621b. ai /ac), pymetrozine (CGA 215944, Fulfill™ 50 W P, 0.094 lb. ai/ac), pymetrozine /fenoxycarb, (SterlingTM ), and fenpropathrin (DanitolTM 2.4 E C, 0.20 lb. or 0.10 lb. ai/ac) /acephate (OrtheneTM 90 S, 0.5 or 0.25 lb. ai /ac) were made against silverleaf whitefly, Bemisiq grgentifolii Bellows and Perring, at UA, Maricopa Agric. Ctr. Six applications (plus adjuvant Kinetic) were applied on 9 treatments. Ten treatments (embedded control included) were in a double tier complete random block design and there was I adjacent, 1.5 ac control block (treatment 11). Eggs and large nymphs were sampled weekly post application to determine efficacy; reported as % reduction from block control. Rotation schemes were: 1) 3 pymetrozine /fenoxycarb, then 3 fenpropathrin/acephate applications, 2) 3 pymetrozine 2 /3rate /fenoxycarb full rate, then 3 fenpropathrin /acephate applications, 3) fenoxycarb 6 applications, 4) pymetrozine 6 applications, 5) 3 fenpropathrin /acephate, then 3 pymetrozine /fenoxycarb applications, 6) 3 fenpropathrin /acephate, then 3 pymetrozine /fenoxycarb, 7) fenpropathrin /acephate at full, l/2, full, then 3-1/2 rate applications, 8) 2 pymetrozine /fenoxycarb, 2 fenpropathrin /acephate, 1 pymetrozine /fenoxycarb, and 1 last fenpropathrin /acephate application, 9) 2 fenpropathrin /acephate, 2 pymetrozine /fenoxycarb, 1fenpropathrin/acephate, and 1 last pymetrozine /fenoxycarb application, 10) embedded control, and 11) block control. Egg % reductions for season means ranged from 93-99% for combinations and rotations of them. Last % season analyses showed reductions from 95-99 %. Pymetrozine had a 98% reduction andfenpropathrin /acephate had 98 % egg reduction. Nymphal reduction for season means ranged from 80-95% for combinations and rotations of them. Last % season analyses, showed % reductions from 91-98 %. Pymetrozine had 92% reduction and fenpropathrin /acephate had 92% reduction of nymphs (season). These studies showed that pymetrozine, pymetrozine /fenoxycarb, fenpropathrin/acephate combinations and rotations provided excellent control of silverleaf whitefly immatures.
    • Susceptibility of Lygus Bug Populations in Arizona to Acephate (Orthene®) and Bifenthrin (Capture®), with Related Contrasts of Other Insecticides

      Dennehy, T. J.; Russell, T. J.; Silvertooth, Jeff; Extension Arthropod Resistance Management Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Adult lygus bugs, Lygus hesperus (Knight), were collected from alfalfa fields in 11 different cotton producing areas of Arizona. A standardized glass vial method was used to estimate susceptibility of the collected populations to the organophosphate insecticide, acephate (Orthene®), and the pyrethroid bifenthrin (Capture®). Overall, lygus from throughout the state were significantly less susceptible to acephate and bifenthrin in 1995, than in 1994. Resistance of lygus to acephate continues to be widespread and intense, but not uniform in Arizona. In 1995, all populations possessed individuals capable of surviving exposure to vial treatments of 10,000 μg/ml acephate. Lygus bugs from Safford and Maricopa represented the most and least susceptible populations, respectively, to both acephate and bifenthrin. These two populations were tested for susceptibility to nine other insecticides: aldiaarb (Temik®), dimethoate (Gowan Dimethoate E267®), endosulfan (Gowan Endosulfan 3EC®), imidacloprid (Admire 2F®), malathion (Gowan Malathion 8®), methamidophos (Monitor 4®®), methomyl (Lannate LV®), oxamyl (Vydate 3.77L®), apt oxydemeton- methyl (Metasystox-R SC®). The Maricopa population was significantly less susceptible to six of these insecticides. Our findings support the hypothesis that the intensive use of pyrethroid and organophosphate insecticides for whitefly control in cotton has selected for resistance in lygus. This result portends increased problems with lygus control in the future, points to the need for developing new tools for controlling lygus bugs in Arizona cotton, and underscores the urgent need to find alternatives to the current heavy reliance on insecticides for managing whiteflies in cotton.
    • Evaluation of Irrigation Termination Management on Yield of Upland Cotton, 1995

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      A single field study was conducted in 1995 at the Maricopa Agricultural Center (1100 ft. elevation) to evaluate the effects of three dates of irrigation termination on yield a common Upland cotton variety (DPL 5415). Planting date was 3 April (469 HU /Jan 1 86/55° F thresholds). Following difficult establishment, crop vigor was generally low all season, with a relatively strong level of fruit retention. Three dates of irrigation termination an -1T3) were imposed based upon crop development into cut -out, with IT1 (21 August) set such that bolls set at the end of the first fruiting cycle would not be water stressed and could be fully matured. The third termination (IT3) date was 22 September, which was staged so that soil moisture would be sufficient for development of bolls set up through the first week of September. The second irrigation termination (IT2, 1 September) was intermediate to IT1 and IT3. Lint yield results revealed a 139 lb. lint/acre difference between IT1 and IT3, which was statistically significant (P < 0.05).