• Arizona Upland Cotton Variety Testing Program, 1996

      Silvertooth, J.; Norton, R.; Clark, L.; Husman, S.; Knowles, T.; Howell, D.; Stedman, S.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Eleven field experiments were conducted in many of the cotton growing areas of Arizona in 1996 for the purpose of evaluating Upland cotton varieties in terms of adaptability and performance. Five commercial cottonseed companies participated in the program. Two varieties were submitted from 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. The 1996 season offered some extremes in terms of weather conditions, with very hot summer temperatures, particularly in July and August. The hot summer weather conditions were primarily difficult in relation to higher humidities (dewpoints) with high night and daytime temperatures. Variety performance under these extremes offers an opportunity for review and compare with regard to adaptability, or what is commonly referred to as "heat tolerance". The 1996 season was very similar in this respect. Each of the participating seed companies offer a compliment of varieties that can serve to match various production strategies commonly employed in the state as well as showing a strong capacity to be regionally adaptive.
    • Fertilizer Nitrogen Recovery in Irrigated Upland Cotton

      Navarro, J. C.; Silvertooth, J. C.; Galadima, A.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Field studies were carried out for the purpose of evaluating fertilizer nitrogen (N) recovery of upland cotton by use of the difference technique. The treatments under study included : i) check (no fertilizer N applied), ii) standard approach (preplant and sidedress), iii) feedback approach (based upon soil and plant factors), and iv) 2X feedback approach. The studies were carried out at two locations Maricopa (MAC) and Marana (MAR). MAC is a low elevation location with a coarser textured soil compared to the MAR location. 'DPL-20' was the variety used in both locations, except for the early years at MAC where 'DPL-90' was used. The sources of fertilizer N were urea and ammonium sulphate, which were sidedress and split applied. In general, for the MAC location the final N fertilizer rates (NFR) applied were higher than for MAR due to higher yield potentials. The total N uptake increased as the NFR increased. The N use efficiency (NUE) values were reduced as NFR increased. The N fertilizer uptake (NFU) showed a decreasing pattern in the first years, and then an increasing trend; which was coupled with rather high amounts of N taken up in the check plot (soil N mineralized). When the N uptake in the check plot was high, NFU values were low, and vice versa. At MAC the N uptake in the check plot, apparently due to mineralized soil N revealed a slight increasing trend during the first years and then, after the fourth year, a rapid reduction of the mineralized soil N (check plot). A similar pattern was observed for MAR, although the total amount of N taken up was smaller compared to the MAC location.
    • Short Staple Variety Trials in Cochise County, 1996

      Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Variety trials were grown at two locations and with two different sets of short staple varieties. One trial on the Robbs farm, north of Kansas Settlement, tested seven acalas varieties from New Mexico and California and one variety from Australia. The other trial on the Noel Curry farm, near the town of Cochise, tested nine upland varieties as part of the statewide testing program and three acalas from NM and CA. The highest yielding variety in our tests was SG 125 with a yield over 3 bales per acre. In the acala study, the Australian variety and an experimental from NM were the highest yielding varieties with yields just over 2 bales per acre. Lint quality of each variety and an estimated crop value are also given in this paper.
    • 1996 Low Desert Upland Cotton Advanced Strains Testing

      Husman, S. H.; Jech, L. E.; Metzler, F.; Wegener, R.; Johnson, K.; Silvertooth, Jeff; Maricopa County Cooperative Extension, University of Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Upland cotton advanced strains and commercial check comparison varieties were evaluated in replicated field studies in 1996 on Cooperator fields in Queen creek, Buckeye, and Gila Bend, AZ. Eight seed companies submitted advanced strains plus a commercially available check of their choice for each site. The highest lint yields for advanced strains entries by location were: J & S Research JSX 12 (1890 lb./acre), Delta Pine and Land Co. DPX 1075 (1420 lb/acre) and Delta Pine and Land Co. DPX 1075 (2510 lb/acre) at Queen Creek, Buckeye and Gila Bend, Arizona respectively.
    • Nitrogen Management Experiments for Upland and Pima Cotton, 1996

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Three field experiments were conducted in Arizona in 1996 at three locations (Maricopa, Marana, and Safford). The Maricopa and Safford experiments have been conducted for seven consecutive seasons, the Marana site was initiated in 1994. The purposes of the experiments were to validate and refine nitrogen (N) fertilization recommendations for both Upland and Pima cotton. The experiments each utilized N management tools such as pre-season soil tests for NO₃⁻-N, in- season plant tissue testing (petioles) for N fertility status, and crop monitoring to ascertain crop fruiting patterns and crop N needs. At each location, treatments varied from a conservative to a more aggressive approach of N management. Results at each location revealed a strong relationship between the crop fruit retention levels and N needs for the crop. This pattern was further reflected in final yield analysis as a response to the N fertilization regimes used. The higher, more aggressive, N application regimes did not benefit yields at any location.
    • Evaluation of Irrigation Termination Management on Yield of Upland Cotton

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      A single field study was conducted in 1996 at the Maricopa Agricultural Center (1,175ft. elevation) to evaluate the effects of two dates of irrigation termination on the yield of a common Upland cotton variety (DPL 5415). Planting date was 11 April (667 HU/Jan 1 86/55° F thresholds. Two dates of irrigation termination (IT1 - IT2) were imposed based upon crop development into cut-out, with IT1 (14 August) being provided such that bolls set at the end of the first fruiting cycle would not be water stressed and could be fully matured The second termination (IT2) date was 10 September, which was staged so that soil moisture would be sufficient for development of bolls set up through the first week of September. Lint yield results revealed no differences between IT1 and IT2.
    • Conservation of Natural Enemies Relative to Use of Insect Growth Regulators for Control of Sweetpotato Whitefly

      Naranjo, Steven E.; Hagler, James R.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      As part of a large-scale, multi-institutional experiment in 1996 to examine and demonstrate strategies for management of Bemisia tabaci involving the use of two insect growth regulators (IGRs), we evaluated effects on the abundance and activity of native natural enemies. For parasitoids there were significant differences between insecticides regimes on 4 of 10 sampling dates. In general, parasitoid abundance and rates of parasitism were depressed in treatment plots receiving a rotation of conventional chemistry in comparison with those receiving IGRs. There was no apparent effect of any of the treatment variables on parasitoid emergence (immature survival). Results for arthropod predators are still preliminary, but densities were generally depressed in plots receiving a rotation of conventional insecticides in comparison with those receiving IGRs. These preliminary results suggest that use of IGRs for suppression of B. tabaci may help conserve populations of important natural enemies.
    • Using Drainage Lysimeters to Evaluate Irrigation and Nitrogen Interactions in Cotton Production

      Martin, E. C.; Pegelow, E. J.; Watson, J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Although the cost for water is one of the largest expenditures in a grower's budget in Arizona, many growers in the state still over- irrigate their fields to assure that there will be no yield losses. These excess irrigations usually do not cause any negative effects to the crop, they can cause the loss of available nitrogen to the plant and the potential for nitrate contamination of groundwater resources. To assess the impact that excess irrigation may have on cotton yields and the potential for groundwater contamination, a drainage lysimeter study was initiated at the Maricopa Agricultural Center, Maricopa, Arizona. Drainage lysimeters are large, open- topped steel boxes filled with soil and placed underground in the experimental field. Crops are grown directly above the lysimeters and the water that moves through the soil profile is collected at the bottom of the lysimeter and analyzed. In this study, three lysimeters were installed. The lysimeters were 80" wide (two row widths), five feet long, and six feet deep. They were placed 18 inches below the soil surface and filled with soil as to best represent the soil in its natural condition. The data presented in this paper are from two years of an ongoing experiment. Throughout the growing season, water samples were taken from the lysimeters in the field. Nitrogen applications were made according to field conditions and weekly petiole sampling. Irrigations were made according to field conditions and using the AZSCHED irrigation scheduling program. Treatment one was irrigated according to the schedule recommended by AZSCHED. The amount applied was equal to the total crop water use since the last irrigation. In treatment two, the timing was the same as treatment one, but the amount of irrigation water applied was 1.25 times more. Treatment three was also irrigated at the same time but with 1.5 times more water. Yield samples were taken at the end of each season and showed no significant differences between treatments, with yields averaging about 1100 lb./acre of lint in 1995 and 940 lb./acre of lint in 1996. The drainage amounts ranged from 9.5" in treatment three to 2.5 inches in treatment one. The corresponding nitrate-N losses were 56.9 lb. N/acre for treatment three and 33.4 lb. N/acre for treatment one. Monitoring continued during the winter to assess the impact of winter rainfall. In the last two years, there has been no significant winter rainfall.
    • Commercial Field Performance of KNACK™ on Cotton in the Yuma Valley

      Palumbo, John C.; Hannan, Todd A.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      The insect growth regulator, Knack was evaluated for efficacy against sweetpotato whitefly in paired plots within three commercial cotton fields near Somerton, Arizona. A single application of Knack and Danitol/Orthene was made in July and the impact on whitefly populations, natural enemies and secondary pests was measured for 40 d. Knack appeared to act slowly during the first 2 weeks, but after 21 days nymph populations were greatly reduced. Populations of nymphs and adults began to return to their pre-test levels after 40 d. The Danitol/Orthene application resulted in a significant decrease in adult numbers. Initially nymph densities declined, but after 14 d densities appeared to increase at a much greater rate than was observed in the Knack plots. Under the conditions experienced in this study, a single application of Knack in early July provided protection against sweetpotato whitefly as good, or better than experienced with Danitol/Orthene. Reductions in yields or lint quality attributable to whitefly were not observed in either treatment regime. Although beneficial predators were measured throughout the season, insecticide sprays for lygus control prevented significant buildup of populations. However, the numbers of Liriomyza leafminer adults captured on sticky traps were significantly lower in Knack-treated plots.
    • Cotton Defoliation Evaluations, 1996

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Two field experiments were conducted near Coolidge and Marana, AZ in 1996 to evaluate the effectiveness of a number of defoliation treatments on Upland (var. DPL 5415) and Pima (var. S-7) cotton.. All treatments consisted of materials commercially available in Arizona, and each showed promise in terms of overall effectiveness. Results do reinforce recommendations regarding the use of low rates (relative to the label ranges) under warm weather conditions and increasing rates as temperatures cool.
    • Pima Regional Variety Test at the Maricopa Agricultural Center, 1996

      Hart, G. L.; Nelson, J. M.; Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Eighteen Pima varieties and experimental strains were grown in a replicated trial at the Maricopa Agricultural Center. Lint yield, boll size, lint percent, plant height and fiber data are presented in this report.
    • Demonstration to Manage Pink Bollworm with BT Cottons, Yuma Valley Ag Center, 1996

      Howell, Don R.; Palumbo, John; Tellez, Alfonso; Hernandez, Humberto; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Transgenic cotton with the Bollgard™ gene inserted has shown great promise in controlling pink bollworm infestations in cotton. This trial was superimposed over a variety trial. Evaluations of pbw infestation indicated remarkable control even though the bolls became infested. Yields were increased in this trial when almost 100% infestation of pbw was allowed to occur. It appears that the trangenic cottons containing Bollgard™ may be an effective method of pbw control.
    • Silverleaf Whitefly on Cotton

      Chu, C. C.; Henneberry, T. J.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory, Brawley, CA and Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Silverleaf whiteflies (SLW), Bemisia argentifolii Bellows and Perring, have been devastating pests of cotton and other crops in Arizona and California in recent years. Studies with cotton insecticide treatments initiated each week from shortly after cotton seedling emergence to late in the cotton season were conducted at the Irrigated Desert Research Station, Brawley, CA. The results suggest action thresholds in relation to cotton yield of 0.22 SLW nymphs/cm² of leaf disc, 0.64 eggs/cm² of leaf disc or 2.22 adults/cm² of yellow sticky card surface.
    • Gila Basin Voluntary Pest Management Project, 1995 and 1996

      Jech, L. E.; Husman, S. H.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Growers, Pest Control Advisors and Cooperative Extension, University of Arizona personnel coordinated areawide pest management activities in an area near Gila Bend, AZ to maximize the effectiveness of strategies to control pink bollworm and whitefly. Data on insect populations and pesticide applications is held within a database that is shared with cooperators on a real time basis. Control measures are discussed and common goals reached for reduction of pests within the area. Assessments from growers support the whitefly survey activities of the personnel. Fields were surveyed once per week. Data describing the population is faxed or phoned to the Pest Control Advisor and remedial action implemented at their discretion. Cooperative Extension personnel suggested pesticide use patterns to reduce resistance of whitefly and checked for field populations using University of Arizona recommendations. In 1995 an areawide pin head square program was followed based on Heat Units After Planting for timing pink bollworm susceptible stage of the cotton plant for each field and combined with the Heat Unit Model for pink bollworm emergence to determine percent emergence of the population. In 1996, many of the growers planted genetically engineered cotton and used lures to reduce pink bollworm and used the insect growth regulators under the Section 18 for whitefly control.
    • Evaluation of Calcium Soil Conditioners in an Irrigated Cotton Production System

      Griffin, J. R.; Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      In 1996 a single field experiment was conducted at Paloma Ranch, west of Gila Bend in Maricopa County Arizona. Nucoton 33B was dry planted and watered -up on 15 April. Treatments consisted of various rates and times of application of nitrogen (N) and calcium (Ca) from two sources (N-Carm and CAN-17), as well as a standard N source, UAN-32, along with a Calcium (Ca) check which received no Ca. Treatments], 2, and 3 each received a total of 280 lbs. N/acre. Treatment 4 received a total of 210 lbs. N/acre while treatment 5 received a total of 301 lbs. N/acre. Treatment 1 was a check plot and received only standard applications of UAN-32. Treatments 2 and 4 each received a total of 72 lbs. of Ca/acre. Treatment 5 received a total of 79 lbs. Ca/acre while treatment 4 received a total of 300 lbs. Ca/acre. No significant differences were found among the various treatments in terms of plant growth, soil water content, ECₑ values, and sodium absorption ratios. Lint yields were significantly different (P < 0.07).
    • The 1997 Arizona Cotton Advisory Program

      Brown, P.; Russell, B.; Silvertooth, J.; Ellsworth, P.; Stedman, S.; Husman, S.; Howell, D.; Knowles, T.; Clark, L.; Dunn, D.; et al. (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Arizona Cooperative Extension generates and distributes weather-based Planting Date and Cotton Development Advisories for 15 cotton production areas (Marana, Laveen, Paloma, Litchfield Pk., Pinal Co., Parker, Mohave Valley, Queen Creek, Safford, Yuma Valley, Aguila, Cochise Co., Greenlee Co., Harquahala and Wellton-Mohawk). Planting Date Advisories are distributed from shortly after legal first planting date until the end of April and stress 1) planting cotton varieties according to heat unit accumulations rather than calendar date and 2) the importance of weather conditions and 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 1997, and growers may obtain advisories by mail /fax from local extension offices or by computer from the AZMET computer bulletin board system or AZMET Internet Web Page (http://ag.arizona.edu/azmet). Major program changes planned for 1997 include 1) providing heat stress information on Crop Development Advisories and 2) the addition of an advisory for the Wellton-Mohawk area.
    • Upland and Pima Cotton Demonstration Using IGR's Knack and Applaud to Control Silverleaf Whitefly at the Yuma Valley Ag Center in 1996

      Howell, D. R.; Palumbo, J.; Nelson, J.; Hernandez, H.; Gayler, R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      The section 18 granted for the use of insect growth regulators in 1996 in Arizona provided an excellent opportunity to demonstrate the efficacy of the materials. Knack® (Pyriproxyfen) and Applaud® (Buprofezin) both demonstrated excellent control of whitefly in this demonstration. Efficacy of the insect growth regulators was monitored by using the "Ellsworth-Naranjo" methods of measuring adult and nymph whitefly numbers. This method provided good tracking of the populations throughout the period monitored. The areas treated were cotton variety trials both pima and upland. On the upland trial whitefly infestation data was collected on each variety. Hairy leaf varieties tended to have higher whitefly numbers of both adults and nymphs.
    • Management of Pyrethoid-Resistant Whiteflies in Arizona Cotton: Selection, Cross-Resistance, and Dynamics

      Sivasupramaniam, Saku; Dennehy, Timothy J.; Williams, Livy III.; Silvertooth, Jeff; Extension Arthropod Resistance Management Laboratory, The University of Arizona, Department of Entomology, Tucson, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      In 1995, silverleaf whitefly, Bemisia argentifolii Bellows and Perring, resistance to the widely -used mixture of Danitol® (fenpropathrin) + Orthene® (acephate) was shown to be severe and widespread in Central Arizona cotton. Thereafter, laboratory experiments were undertaken to identify the other major insecticides that were affected by this resistance. Whiteflies were collected in November of 1995 from Maricopa (highly resistant) and Yuma (relatively susceptible) County locations in Arizona. A composite colony was established by combining Yuma and Maricopa whiteflies in a 4:1 ratio. After six generations of adult selection of this population with Danitol + Orthene, appreciable shifts in the concentration responses for pyrethroid, organophosphate, and carbamate insecticides were observed, indicating heritable variation for resistance in the source populations. From this we obtained definitive proof that resistance to Danitol + Orthene confers cross-resistance to Asana® (esfenvalerate), Capture® (bifenthrin), Danitol, Decis® (deltamethrin), Decis + Orthene, and Karate® (lambda-cyhalothrin). Additionally, selection with Danitol + Orthene resulted in statistically significant reductions in susceptibility to Curacron® (profenofos), Lannate® (methomyl), Monitor® (methamidaphos), and Ovasyn® (amitraz). Studies were performed to assess tolerance of Maricopa (pyrethroid- resistant) and Yuma (pyrethroid-susceptible) populations to a diversity of conventional insecticides currently registered for use in Arizona cotton, with the intention of finding compounds that showed promise for overcoming pyrethroid resistance. Of the materials evaluated, Curacron, Lannate, Lorsban® (chlorpyrifos), Ovasyn, Supracide® (methidathion), and Vydate® (oxamyl) were most promising. To determine to what degree pyrethroid resistance in cotton influenced resistance in winter vegetables and melons, and vice versa, whitefly populations were collected from a succession of these crops in Western and Central Arizona regions. In most instances, the whiteflies in Western Arizona were significantly more susceptible to Danitol + Orthene than those in Central Arizona. Significant decreases were found in susceptibility to Danitol + Orthene during the 1996 season at three of the four locations in which multiple crops were monitored. This emphasizes that pyrethroid resistance levels can be increased in whitefly populations from any of the cotton, melons, or other winter vegetable crops evaluated. Therefore, management of pyrethroid resistance in Arizona cotton will require harmonizing resistance management efforts and specifically limiting pyrethroid use in the entire crop complex.
    • Side-Dress Temik® Effects on Lint Yields

      Husman, S. H.; Deeter, B.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      Temik 15G was side -dressed at a rate of 7 lb./acre and 14 lb./acre and compared to an untreated check in two experiments in Buckeye, Az.. Treatments were made prior to the second in- season irrigation (June 3 and June 5) which was just prior to early bloom. Lygus counts were taken using a sweep net on weekly intervals for six weeks post application. The first experiment resulted in a significant increase of 123 lb. and 1241b. lint in both the 7 and 14 lb. rate treatment respectively over the untreated check. The second experiment resulted in a significant 102 lb. lint increase for the 7 lb. treatment with no significant difference for the 14 lb. treatment to the check.
    • Evaluation of a Feedback Approach to Nitrogen and Pix Application

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1997-03)
      A single field experiment was conducted in 1996 at Maricopa, AZ to compare a scheduled approach (based on stage of growth) versus a feedback approach (based on vegetative status) to both nitrogen (1V) and mepiquat chloride (PIX™) applications on Upland cotton (Gossypium hirsutum L.). PIX feedback treatments were based upon fruit retention (FR) levels and height to node ratios (HNRs) with respect to established baselines. Scheduled and feedback PIX applications were made for a total of 0.75 and 1.25 pt./acre, respectively, with the scheduled treatments being initiated earlier in the fruiting cycle (early and peak bloom). Feedback PIK treatments consisted of a single 0.75 pt./acre application near peak bloom (approx. 2200 heat units after planting (HUAP), 86/55°F threshold). Scheduled applications of fertilizer N totaled 225 lbs. N/acre from three applications and feedback N treatments received a total of 135 lbs. N/acre from three applications. Treatments consisted of all combinations of scheduled or feedback applications of both N and PIX The highest lint yields were from a treatment receiving feedback N and PIX, but all treatment yields were not significantly different (P ≥ 0.05) from one another. From a practical (economic) standpoint, however, these treatments were different in terms of the differences of fertilizer N and the timing of the PIX applications required to produce comparable yields. Results from 1996 are consistent with 1993, 1994, and 1995 results from the same study.