• Sweetpotato Whitefly: Flight Activity, Effects of Wind Velocity, and Precopulatory Pairing Activity Patterns

      Butler, George D. Jr.; Henneberry, T. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Sweetpotato whitefly (SPW), Bemisia tabaci (Gennadius), exhibited high levels of flight activity during daylight hours from July to September. Flight activity in a fallow field in Arizona in late August began as early as 0600 h, peaked between 0800 and 0900 h, and decreased thereafter during the day. Flight activity in cultivated cotton, lettuce and alfalfa fields also occurred throughout the day in early and late September. Few SPW were caught between 1900 and 0700 h. Peak numbers were caught on sticky traps prior to 1200 h in Arizona and Israel. Numbers of adults caught on sticky traps decreased from 0700 to 1000 h and with increasing wind velocity. Precopulatory pairing behavior occurred as early as 0700 h and increased gradually to 0900 to 0920 h, when 48% of the adults observed were paired, and decreased thereafter.
    • 1991 Cotton Replant Decisions, Safford Agricultural Center

      Clark, Lee J.; Carpenter, Eddie W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Each planting season in the Safford valley there are fields that suffer stand reduction from adverse weather conditions. This study addresses some of the options and the economical effects from exercising these options on a field at the Safford Agricultural Center. References are made to work in California that have quantified the yield effect of stand reduction and chilling damage to cotton seedlings. This study shows that patience may pay better than rushing into the field to replant or rewater.
    • Cottonseed Treatment Evaluations in Arizona, 1991

      Silvertooth, J. C.; Malcuit, J. E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Field experiments were conducted at three locations in Arizona (Maricopa, Marana, Safford) to evaluate 12 cottonseed treatments on Upland cotton (G. hirsutum L.). Stand counts were taken to evaluate the effectiveness of each treatment. Statistical analysis showed no significant differences among the treatments used at the Marana location. Significant differences were found among the treatments used at the Maricopa and Safford locations.
    • Use of Treated-vial Technique to Determine Efficacy of Several Insecticides against the Sweetpotato Whitefly, Bemisia tabaci (Gennad.)

      Sivasupramaniam, S.; Kelly, S. E.; Cross, D.; Brown, J.; Watson, T. F.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      A treated -vial technique was used to bioassay insecticide susceptibility of sweet potato whitefly populatons occurring on different hosts and at different locations in southern Arizona. All insecticides tested proved to be efficacious against the sweetpotato whitefly. Combinations improved efficacy, for example, Orthene to Danitol and DEF to Baythroid. Three important factors appeared to affect efficacy: 1) geographic site; 2) host plant of SPWF; and, 3) time of season. Further detailed experimentation needs to be done to elucidate the reasons for this.
    • Dissolved Nitrogen Compounds in Integrated Aquaculture Effluent

      Brooks, George Benjamin Jr.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Integrated aquaculture utilizing pre- irrigation water will hypothetically increase the levels of dissolved nitrogen products in the resulting effluent. Research was performed to assess the levels of additional nutrients added. The results suggest however, that integrated aquaculture may reduce the amount of nitrogen as nitrate applied to the fields.
    • Cotton Yields: Nitrogen and Harvest Aid Effects

      Chu, Chang-chi; Henneberry, Thomas J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      The results of field studies with N rates from 0 to 336 kg/ha, in combination with two growth regulators, ethephon (Prep® ɑ-chloroethyl phosphonic acid, Rhone-Poulenc Ag Co., Research Triangle Parr NC) and thidiazuron (Dropp® N- phenyl -N' -1,2,3 -thiadiazol -5ylurea, Nor-Am Ag Prod. Inc., Naperville, IL). Results showed that sidedress applications of N (ammonium nitrate) to cotton did not influence the defoliation effects of ethephon and thidiazuron, or reduce number of immature green bolls at harvest. Under short-season conditions, sidedress N applications did not effect yields. Ethephon and thidiazuron at the rates tested did not affect cotton lint yields. Thidiazuron alone or in combination with ethephon resulted in high percentages of cotton defoliation.
    • Pima Cotton Genetics

      Percy, R. G.; Turcotte, E. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      An investigation was conducted to determine the inheritance, allelism, and linkage associations of a spontaneous, male- sterile mutant found in plants of American Pima (Gossypium barbadense L.) cotton. Analyses of F₁, F₂, and BC populations of the mutant indicated that it was inherited as a single, recessive gene. T ests for allelism of the new gene with three previously described recessive male - sterility genes (ms₁, ms₂ and ms₃) were negative. Analyses of F₂ population segregation from crosses to 23 mutant marker stocks produced no evidence of linkage associations. We have proposed that the male sterility mutant be designated male-sterile-13 and be given the gene symbol ms₁₃. A conversion program to convert photoperiodic short-day accessions of a Gossypium barbadense germplasm collection to day neutrality continues.
    • Community-wide Insect Management Program in Pima County, 1991

      Moore, Leon; Thacker, Gary; Watson, Theo; Ellsworth, Peter; Combs, Jack; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      The Marana-Avra Growers' Task Force and Arizona Cooperative Extension worked together to implement a comprehensive, community-wide insect management program. Growers worked in unison to implement a number of Integrated Pest Management techniques; including uniform optimal planting dates, trap cropping, pinhead square spray applications, in-season insect management, and late season management. This strategy focused on the area's primary pest, the pink bollworm (PBW). This program delayed the need to treat for PBW until late August and minimized secondary pest problems. However, research results on the effectiveness of trap crops were inconclusive.
    • Irrigation Efficiencies, Nitrogen Applications, and Lint Yields of Upland Cotton Grown at the Marcopa Agricultural Center, 1991

      Sheedy, Mike; Watson, Jack; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      The computer program AZSched, with weather data obtained from AzMet, was used to schedule irrigation for a yield trial of Upland Cotton (DPL 90) at the Maricopa Agricultural Center in 1991. Cotton lint yields were compared between plots from four treatments involving the combination of two irrigation efficiencies (70% and 90 %) and two nitrogen fertilizer applications (broadcast and sidedress). The amount of nitrogen fertilizer applied to the broadcast plots was 145# N /A. One hundred thirty pounds NIA was applied to the sidedressed plots. A potassium bromide tracer was applied to select areas in each plot at the time of initial fertilization. Soil samples from each plot were taken to a depth of 10' for analysis of bromide and nitrate to determine the depth of water movement through the soil profile. Irrigation amounts averaged 42.8" for 70% efficiency and 36.7" for 90% efficiency. No significant difference in lint yield was noticed between the two nitrogen fertilizer applications, but significant differences existed between the two irrigation efficiencies.
    • A Native Weed as a Trap Crop for Whiteflies in Cotton

      Ellsworth, Peter C.; Chernicky, Jon P.; Byrne, David N.; Gibson, Roberta; Meade, Donna; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      A field study was conducted during 1991 to evaluate the effectiveness of Physalis wrightii Gray, as a trap crop for Bemisia tabaci (Gennadius) when grown with the commercial crop Gossypium barbedense L. Aldicarb at two rates was used in P. wrightii for control of B. tabaci. Three sampling methods: pan counts, leaf turns, and leaf counts measured B. tabaci numbers in both crops. Aldicarb treatment in the trap crop did significantly affect B. tabaci populations in comparison with untreated P. wrightii (P= 0.000, df =2, 240). Differences in numbers of adults observed on the two hosts were not significant. Analysis of aldicarb metabolite residues by high pressure liquid chromatography exhibited a pronounced dose effect (P= 0.001, df =2, 22) in the trap crop leaf tissues. The chemically treated trap crop did significantly protect the cotton crop from larger and more rapidly developing sweetpotato whitefly populations when compared to the untreated check.
    • Effect of Plant Nitrogen Status on Defoliation of Short-Season Upland Cotton

      Nelson, J. M.; Hart, Gary; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Field studies have been conducted over a four year period at the Maricopa Agricultural Center to determine the influence of nitrogen (N) fertility level on the effectiveness of chemical defoliants for short- season cotton production. Excessive N resulted in dense foliage and cotton that was difficult to defoliate. When plants were deficient in N from mid-season to termination, defoliants were very effective, but lint yields were reduced. The effectiveness of defoliants decreased as the petiole NO₃-N content increased. The optimum fertility program for short-season cotton is one that provides sufficient N during the season to produce maximum lint yields, but allows the crop to become deficient in N at the end of the season, prior to chemical defoliation.
    • The Effects of PIX Application Timing on Lint Yield and Growth and Development Parameters

      Husman, S. H. .; Silvertooth, J. C.; Ramsey, C; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Two field studies were conducted in 1991 to further evaluate Upland cotton yield and development responses to PIX application timing as a function cotton growth stage. Treatments imposed in 1991 were intended to further clarify some response trends observed in previous field studies. Treatments in 1991 were all at the maximum label rate of 1.5 pt./acre with application timing the main variable. Timing was based on growth stage and heat unit accumulation since date of planting. The study in Waddell, Az. resulted in no significant yield differences across all treatments. In contrast, the study at the Maricopa Agricultural Center resulted in a statistically significant yield response by approximately 100 lbs. lint /acre for all FIX treatments compared to the untreated check plots. Plant growth and development measurements indicated the height: node ratio counts to be a good reflection of vegetative tendencies under field conditions in the two studies.
    • The Use of AZSCHED to Schedule Irrigation on Cotton, Safford Agricultural Center - 1991

      Clark, Lee J.; Carpenter, Eddie W.; Slack, Donald C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Irrigation scheduling software has been developed that is menu driven, user friendly and capable of scheduling up to 60 fields. This software is demonstrated scheduling irrigation on both Pima and upland cotton in this paper.
    • 1991 Yuma County Upland Cotton Variety Trial, Wayne Stuhr Farm - Wellton, AZ

      Howell, Don R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
    • Insecticidial Control of the Sweet Potato Whitefly in Cototn

      Watson, T. F.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Four field experiments were conducted to evaluate efficacy of a number of registered or experimental insecticides against the sweet potato white fly. Several materials gave encouraging results under unusually high population densities. Among the more effective treatments in one or more tests were: Capture, Danitol, NTN 33893, pyriproxyfen and SN 85292, and combinations of Capture +endosulfan, Capture +Ovasyn and Danitol +Orthene.
    • Plant Population Effects on Pima S-6 Lint Yield

      Husman, S. H.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      A replicated field study was conducted at the Maricopa Agricultural Center in 1991 to investigate the effect of plant population density on Pima S-6 lint yield. Treatments ranged from a low of 10,465 plants per acre to a high of 65,000 plants per acre. There were no significant yield differences observed with populations between 17,000 plants per acre and 65,000 plants per acre. Significant yield decreases occurred when populations were reduced below 17,000 plants per acre.
    • The Arizona Cotton Advisory Program

      Brown, P.; Russell, B.; Silvertooth, J.; Moore, L.; Stedman, S.; Thacker, G.; Hood, L.; Husman, S.; Howell, D.; Cluff, R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Arizona Cooperative Extension produced and distributed weather -based Planting Date and Cotton Development Advisories for 8 cotton production areas (Marana, Litchfield Pk, Pinal Co., Parker, Safford, Yuma Valley, Dateland and Aguila) in 1991. Planting Date Advisories were distributed from mid - February through the end of April and stressed 1) planting full season cotton varieties according to heat unit accumulations rather than calendar date and 2) the importance of soil temperature to good germination. Cotton Development Advisories were distributed from early May through mid- September and provided growers updates on crop development, insects, weather and agronomy. The Cotton Advisory Program will continue in 1992 with the major change being an expansion in coverage to include Paloma, Queen Ck, and Mohave Valley.
    • Weather Conditions during the 1991 Growing Season

      Brown, P.; Russell, B.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      The 1991 growing season was characterized by a cool, wet spring and a cool, dry summer. Heat unit accumulation for the season was the lowest in 5 years at most locations. Precipitation was concentrated in two periods: early (Jan. - Mar.) and late (Nov. - Dec.). Summer rainfall was well below normal at most locations.
    • Evaluation of Date of Planting and Irrigation Termination on the Yield of Upland and Pima Cotton

      Silvertooth, J. C.; Watson, T. F.; Malcuit, J. E.; Brown, P. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Five field experiments were conducted at three locations in 1991 in Arizona to evaluate the response of Upland and Pima cotton to dates of planting and dates of irrigation termination. Planting dates ranged from as early as 2 April in the Yuma Valley (150 ft. elevation) to 14 May at Marana (2,000 ft. elevation). Dates of irrigation termination ranged from 8 August in the Yuma Valley to 24 September at Maricopa. Planting date was commonly a significant effect in these experiments, particularly with Pima cotton. Irrigationtermination results over three locations and three seasons show increases of approximately 50 to 100 lbs. lint /acre by extending later irrigations.
    • Short Staple Variety Trial, Cochise County, 1991

      Clark, Lee J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1992-02)
      Three new California acala varieties are evaluated in this field trial along with nine New Mexico acalas. The highest yielding variety was New Mexico's 1517-88 with a yield of 2.8 bales per acre. California's MAXXA came in number 3, but not very far behind, yieldwise. Nazas 77, a rust resistant variety from Mexico,was evaluated in a second trial at this same location. Rust was not a problem at this site in 1991 so its rust- resistance could not be evaluated, but it yielded within 5% of the yield of 1517-88.