• 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.
    • Short Staple Regional Cotton Variety Trials, Graham County, 1997

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Two on farm, replicated short staple variety demonstrations were planted in 1997. Twelve varieties were evaluated on the Carpenter farm in Central and on the Colvin farm in Eden. Several new varieties were planted in both studies, including 2 transgenic varieties, DP 35B and BXN 47, 2 varieties from Australia and four other varieties seen for the first time. DP 35B and Stoneville 474 were the highest yielding varieties in Central and the Australian variety, IF 1003, had the highest yield in Eden with yields over 2 bales per acre. Other agronomic data from the varieties and 11111 values from the lint are also included in this report.
    • Marana Upland Test

      Hart, G. L.; Nelson, J. M.; Barney, Glen; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Twenty four upland cotton varieties were grown at the Marana Agricultural Center. Lint yield, boll size, lint percent, plant population and fiber property data are presented in this report.
    • 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.
    • Upland Regional Cotton Variety Test at the Maricopa Agricultural Center, 1997

      Hart, G. L.; Nelson, J. M.; Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Thirty four upland cotton varieties were grown at the Maricopa Agricultural Center as part of the national cotton variety testing program. Lint yield, boll size, lint percent, plant population and fiber property are presented in this paper.
    • Evaluation of 1997 Late-Season Crop Conditions

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      In the latter part of the 1997 season (August) many fields across Arizona, from Marana to the Mohave Valley, were experiencing premature senescence. In an effort to evaluate the conditions leading to the symptoms and to possibly determine the causes, an extensive series of field examinations were conducted in a number of representative fields in central Arizona. Soil samples were taken from selected fields that ranged in expression of the symptoms from very light to severe. Complete analyses of the soil samples were conducted. Plant tissue samples were also collected and analyzed for plant nutrient levels. No absolute causal agent was identified. However, a factor believed to be of significance was that of low soil K levels, where many of the fields expressing the most severe symptoms also had low soil K levels. It is also important to consider the fact that plants exhibiting K deficiency are very similar in appearance to plants affected by Verticillium wilt, which also appeared to be a primary or contributing factor in many cases.
    • Evaluation of Planting Date Effects on Crop Growth and Yield for Upland and Pima Cotton, 1997

      Silvertooth, J. C.; Norton, E. R.; Brown, P. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Three field studies were conducted in 1997 at the Maricopa (1,175 ft. elevation) and Marana (1,974 ft. elevation Agricultural Centers to evaluate the effects of three planting dates on yield and crop development for three representative Upland varieties. Planting dates ranged from 13 March to 8 May and also 312-1159 HU/Jan 1 (86/55° F thresholds). Crop monitoring revealed increased vegetative growth tendencies with later plantings. General trends also showed decreasing lint yield with the later plantings for all varieties at each location.
    • 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.
    • 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.
    • Pima Cotton Regional Variety Trial, Safford Agricultural Center, 1997

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Sixteen 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 1997 was OA 325 with a yield of 746 pounds of lint per acre. It was followed by four other Olvey varieties yielding over 700 pounds per acre. 1997 was not a good Pima cotton year in this valley, weather problems early and insect problems late in the season both took their toll. Yields were more than 300 pounds lower than the previous year and 100 pounds less than in 1995. 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, 1997

      Hart, G. L.; Nelson, J. M.; Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Eighteen Pima varieties were grown in a replicated trial at the Maricopa Agricultural Center as part of the national cotton variety testing program. Lint yield, boll size, lint percent, plant population and fiber property data are presented in this report.
    • Marana Pima Test, 1997

      Hart, G. L.; Nelson, J. M.; Barney, Glen; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Nine pima cotton varieties were grown at Marana Agricultural Center as part of the national cotton variety testing program. Lint yield, boll size, lint percent, and plant population are presented in this report.
    • Efficacy of Experimental Insecticides for Whitefly Control in Cotton, 1996

      Kerns, David L.; Tellez, Tony; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Experimental insecticides were evaluated for control of sweet potato whiteflies relative to a commercial standard in cotton. Ni-25 provided excellent whitefly control and was equivalent to the commercial standard (Knack followed by Danitol + Orthene). Fenoxycarb + pymetrozine provided goodwhitefly control but seemed to require 2 sequential applications before control was equivalent to Ni-25. Diofenolan + pymetrozine appeared to be a slightly weaker treatment, but still provided acceptable whitefly control.
    • 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), 1998-04)
      This is a continuing report on the effects of over -irrigation in cotton production. Started in the Spring of 1995, this study uses drainage lysimeters to study the impact of over-irrigation on nitrate leaching losses. Furthermore, yield and other growth components are monitored to see what effect, if any, the over-irrigation has. The study was initiated at the Maricopa Agricultural Center, Maricopa, Arizona. The drainage lysimeters used 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, two 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 three 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 1.5 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, 940 lb./acre of lint in 1996 and 1300 lb./acre in 1997. Cumulative drainage was 8 inches in lysimeter one and 28 inches in lysimeter two. Nitrate losses for the three years totaled 126 lb. N/acre for lysimeter two and 72.5 lb. N/acre for lysimeter one.
    • Irrigation Efficiencies and Lint Yields of Upland Cotton Growth at the Maricopa Agricultural Center, 1997

      Sheedy, Mike; Watson, Jack; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      A field trial was conducted at the Maricopa Agricultural Center to observe the effects of four irrigation efficiencies (65%, 75%, 85%, and 95%) on the lint yield produced from two upland cotton varieties (DP 5409 and SG 125). Nitrogen requirements for the crop were determined using pre- season soil samples and in season petiole samples in conjunction with crop monitoring data collected at weekly intervals. AZSCHED was used as a guide to the irrigation timing and amount of water applied during the season. This year there was a lint yield response to the different irrigation efficiencies, and a slight difference in yield between the two varieties. Lint yields were significantly lower in the 95% irrigation efficiency plots. Lint Yields ranged from 1448 # lint /acre (SG125 at 75%) to 1220 # lint/acre ( DP5409 at the 65% irrigation efficiency).
    • 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.
    • 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.
    • Whitefly Management in Arizona: Looking at Whole Systems

      Ellsworth, P. C.; Naranjo, S. E.; Castle, S. J.; Hagler, J.; Henneberry, T. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Whiteflies remain a threat to production of cotton in Arizona. Looking at a series of commercial-scale trials, levels last season were delayed compared to previous years, but at higher densities than in 1995, an outbreak year. Efforts must be expended to optimize insect growth regulator (IGR) use and integrate these tactics with other aspects of crop and pest management. Broad spectrum insecticide use prior to treatment for whiteflies with IGRs alters the ecology of the system. Whitefly densities consistently increased after disruption with a Lygus insecticide relative to Lygus -untreated areas. While Lygus control is a production imperative, guidelines are presented for minimizing the impact of this disruption. The modes of action for the two IGRs differ substantially and result in subtle changes in population age structure and dynamics. The consequences of these changes impact natural enemies and should be noted by producers when selecting an IGR or monitoring populations after treatment. Re- treatment after initial IGR sprays depends on many factors. While apparently similar levels of suppression are possible when only one IGR is used, regimes using both available IGRs resulted in the fewest number of damaging large nymphs late in the season, just prior to defoliation. Conventional insecticides rotated according to pre-IGR introduction guidelines (`95IRM') also suppressed populations significantly and comparably to IGR regimes until late in the season. Then, whitefly densities rose aggressively just prior to defoliation and pyrethroid susceptibility was significantly reduced in the 951RM regime. Full adoption of IGR -based technology along with `Bt' cotton allows growers to better manage whiteflies with fewer disruptions which can lead to secondary pest outbreaks, pest resurgence, and insecticide resistance.
    • Voluntary Area-Wide Whitefly Monitoring Project Implementation 1995-1997, Gila Bend, AZ

      Husman, S. H.; Jech, L. E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Growers, Pest Control Advisors (PCA), and University of Arizona Cooperative Extension personnel formulated and coordinated area-wide pest management strategies in the production area near Gila Bend, Az. from 1995-97. The primary pest target was whitefly with secondary control strategy implementation for pink bollworm in 1995. In 1995-1996, the coordinated effort encompassed approximately 10,000 and 6000 acres which included 10 and 8 cotton producers respectively and 6 pest control advisors. Due to producer interest and initiative in an adjoining production area, project acreage increased to over 18,000 acres and included 14 producers and 9 pest control advisors in 1997. The project cost of $3.00/acre was supported by participating producers with the monies used to hire University of Arizona trained students for field scouting of whiteflies. An economic development grant from the Electrical District #8 supported the project coordinator's salary who is a University of Arizona employee. Each field was sampled weekly for whitefly populations using recommended University of Arizona sampling procedure. The population data was then faxed to the responsible producer and pest control advisor on the date of sample. Treatment thresholds and chemistry class suggestions were made by Cooperative Extension with final control decisions and material choice at the producer and pest control advisor discretion. Weekly community wide meetings were conducted and used to discuss general area-wide and field specific population dynamics, treatment suggestions, crop condition, and agronomic and entomological area -wide production strategy recommendations.
    • Whitefly Management in Arizona: Conservation of Natural Enemies Relative to Insecticide Regime

      Naranjo, Steven E.; Hagler, James R.; Ellsworth, Peter C.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory, Phoenix, AZ; University of Arizona, Maricopa, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1998-04)
      Field studies were conducted in 1997 to evaluate strategies for management of whitefly (Bemisia tabaci). We evaluated the effects of different insecticide regimes (conventional and insect growth regulators [IGR]) on the abundance of native parasitoids and predators associated with whitefly in Arizona cotton. Immature parasitoids were most abundant in untreated control plots and there was little difference among insecticide regimes. Percentage parasitism was low overall (< 30 %), but was highest in Knack plots and lowest in untreated control and Applaud plots. Predator populations were lowest in plots treated with conventional insecticides, and there were several instances where weekly or season -long populations of several predator species/groups were slightly depressed in IGR plots compared with the untreated check. Overall, results are encouraging and indicate that use of IGRs helps to conserve populations of native natural enemies.