• Practical Uses of Crop Monitoring for Arizona Cotton

      Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
    • Preliminary Field Evaluation of an Insect Growth Regulator, Buprofezin, for Control of the Sweetpotato Whitefly, Bemisia Tabaci

      Ellsworth, P. C.; Meade, D. L.; Odom, Phillip; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Two rates of buprofezin and a combination, buprofezin + endosulfan, were compared against Ovasyn® and the standard pyrethroid combination Danitol® + Orthene®. Targeted pests were all stages of the sweetpotato whitefly (SPWF). Danitol + Orthene was the most effective treatment against all SPWF stages. All buprofezin treatments, including the buprofezin + endosulfan combination, were moderately effective against all SPWF stages relative to the untreated check, while Ovasyn had control levels similar to the untreated check. Danitol + Orthene had the highest yield at 4030.2 lbs seed cotton/A, and buprofezin + endosulfan had the second highest yield, 2172 lbs/A. All other treatments yielded amounts similar to the untreated check, 863.0 lbs/A. Effects of these control practices on beneficial and other non- target arthropods have not yet been analyzed. Lygus populations were extreme in this test and favored the Danitol + Orthene treatment over the SPWF -specific buprofezin treatments.
    • Seasonal Distribution of Cotton Leafperforator: Pheromone Dispenser Persistence and Effect of Trap Height on Moth Catches in Pheromone Baited Traps

      Leggett, J. E.; Henneberry, T. J.; White, R. D.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      The cotton leafperforator (CLP) Bucculatrix thurberiella Busck. is a sporadic pest in cotton fields of southwest desert area. The cotton leafperforator sex pheromone was identified and synthesized by Hall et al. (1992), thus providing a sensitive method for detecting CLP moths. Tests were conducted in 1992 and 1993 to determine the effective life of CLP polyethylene pheromone dispensers, correlate CLP male moth catches to cotton field infestations, determine the seasonal distribution, and effect of trap height on moth catches. The polyethylene pheromone dispensers were effective for about 4 weeks. The best correlation coefficients for 1993 data, were obtained by comparing CLP moth catches per night to main stem leaf damage at 6 node position from top of plants at field edges. Horseshoe stage CLP per leaf and trap catches had the highest correlation coefficient, r= 0.78. There was more than twice as much CLP damage to leaves at field edges when compared to leaves 10 m into the field. The first CLP moth capture occurred in early to late July and increased rapidly each year in August to 100 to 200 per trap night, but was variable in September, with a high of 300 and a low of 9 per trap night. CLP- baited delta traps placed 0.3 m above ground caught more moths than traps placed at greater heights from 11 to 21 August.
    • Short Staple Cotton Variety Trial, Safford Agricultural Center, 1993

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Fifty three short staple varieties were grown in a replicated field trial on the Safford Agricultural Center. HS SAL 10, a long season variety, was the highest yielding variety in the trial with a lint yield of 1772 pounds per acre. Average yields in this trial were lower than in 1992, even though there were more heat units during the growing season. HVI data for the varieties in the trial are included in this report.
    • Short Staple Variety Demonstrations, Graham County, 1993

      Clark, Lee J.; Cluff, Ronald E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Two on farm, replicated short staple variety demonstrations were established in 1993. Twelve varieties were evaluated in one location and fifteen varieties were evaluated at the other. Delta Pine 90 was the highest yielding variety at one location with a yield of 1387 pounds of lint per acre and Stoneville LA 887 was the highest yielding variety at the other location with a yield of 1134 pounds of lint per acre.
    • Short Staple Variety Trial, Greenlee County, 1993

      Clark, Lee J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Ten short staple cotton varieties including four New Mexico acalas, one New Mexico experimental acala, three California acalas, one hybrid acala and a rust resistant variety from Mexico were tested in the 1993 variety study. The highest yielding variety was Maxxa with a lint yield of 832 pounds per acre. In addition to lint yields; percent lint, boll weights, plant heights and plant populations are shown. Average boll weights are compared between this location and three other elevations varying from 1400 feet to 4100 feet above sea level.
    • Short Staple Variety Trials in Cochise County, 1993

      Clark, Lee J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Variety trials were grown at two locations and with two different sets of short staple varieties. One trial, north of Kansas Settlement, tested nine acalas and one rust resistant variety from Mexico. The other trial, south of Kansas Settlement and east of Pearce, tested three acalas and nine upland varieties. Top yielding varieties were Maxxa, in the acala trial and DPL 2056 in the upland trial. Yields were lower than expected due to adverse weather conditions, including hail.
    • Sweetpotato Whitefly (Bemisia Tabaci Gennadius) Population Relationships to Cotton Yield and Quality

      Chu, C. C.; Henneberry, T. J.; Akey, D. H.; Prabhaker, N.; Perkins, H. H.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Sweetpotato whitefly (SPWF) Bemisia tabaci Gennadius strain B has been a devastating pest of cotton in Arizona and California in recent years. Management systems involving cultural procedures, SPWF population monitoring crop sanitation, crop sequencing chemical control and other technology are developing slowly. SPWF population information in relation to cotton yield and quality losses are urgently needed Preliminary 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 in 1993. The results suggest significant correlations for numbers of SPWF per leaf disc from cotton leaves vs. cotton yield and lint stickiness. Cotton lint yield was negatively correlated to all stages of SPWF populations (-0.783 or higher). Lint stickiness was high positively correlated to SPWF populations (0.707 or higher) and cotton defoliation was positively correlated to SPWF populations (0.876 or higher).
    • Upland Cotton Variety Resposne to Row Spacing

      Husman, S. H.; Silvertooth, J. C.; Jech, L. E.; Wegener, R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      An Upland cotton row spacing study evaluation 30 in. vs. 38 in. rows was conducted in the Gila Valley of western Maricopa County in 1993. In addition, six Upland varieties were also evaluated on both the 30 and 38 in. row configurations. There were no row spacing differences in yield among five of the six varieties. Sure Grow 1001 had significantly lower lint yields when produced on 30 In. rows. DPL 5415 had significantly higher lint yields that the other five tested varieties on 38 in. rows. There were no variety differences in the 30 in. rows.
    • Upland Regional Cotton Variety Test at the Maricopa Agricultural Center, 1993

      Hart, G.; Nelson, J. M.; Clark, L. J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Thirty-six upland cotton 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, gin turnout percent, plant population and fiber property data are presented in this report.
    • The Use of AZSCHED to Schedule Irrigation on Cotton, Safford Agricultural Center - 1993

      Clark, Lee J.; Carpenter, Eddie W.; Slack, Donald C.; Martin, Edward C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      An irrigation scheduling trial was implemented on both long and short staple cotton on the Safford Agricultural Center in 1993. It is a continuation of studies initiated in 1991, where plots were irrigated when they reached 40 %, 50% and 60% soil water depletion level as predicted by the AZSCHED software. Results for this study are given as well as a summary of the three year study.
    • Use of Leaf Water Potentials to Determine Timing of Initial Post-Plant Irrigation

      Steger, A. J.; Silvertooth, J. C.; Brown, P. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Presumably, from a physiological standpoint, early season water stress should be avoided to ensure early fruit initiation, good fruit retention, and optimum yield potential of cotton (Gossypium spp.). This study was conducted to determine the optimum timing of the initial post plant irrigation and the long term effect of postponement on subsequent plant growth patterns, fruit retention, and yield. A short - season Upland variety, (G. hirsutum L.), DPL 20, was planted on 19 April in Marana, AZ, elevation 1970 ft. , on a Pima clay loam (Typic Torrifluvent) soil. Plots (experimental units) consisted of eight 40 in. rows and extended the full length of the irrigation run (600 ft.). Experimental design was a randomized complete block with four replications. Initial post - plant irrigations, designated T1 , 72, and T3, were applied when the midday leaf water potential (ψ) of the uppermost, fully- developed leaf reached -15, -19, and -23 bars, respectively. All treatments received the same irrigation regime following the initial post plant irrigation. Basic plant measurements were taken weekly from each experimental unit. These included plant height, number of mainstem nodes, location of first fruiting branch, fruit retention, number of nodes above the uppermost white bloom, bloom count within a 166 ft² area, and percent canopy cover. Soil -water data at seven 25 cm depth increments was collected from a total of 36 access tubes located within the field study, with three tubes per plot. Lint yields (lb. lint /acre) were 1112, 1095, and 977 for T1 , 72, and T3, respectively. Yields were significantly lower when the initial post plant irrigation was applied after ψ, dropped below -19 bars, confirming the results of a previous study conducted in 1992. Throughout the growing season, height - node ratios (HNR) of T1 and 72 plants were at or above the upper threshold established for DPL 20, while T3 HNR remained close to the expected baseline. Fruit retention was low for all three treatments due to season -long insect pressure from lygus bug. The low fruit retention data reflects the effects of high HNR. Future work will include efforts to separate changes in ψ due to day-to-day climatic variations from those caused by soil -water depletion. A second objective will be to incorporate the data obtained from the neutron moisture meter probe into the study results in an effort to better describe the complete soil-plant-atmosphere continuum as affected by the various treatment regimes employed in this study.
    • Validity of the Pinhead Square Treatment Program for Pink Bollworm Suppression and Impact of Several Insecticides on Arthropod Fauna in Cotton

      Ellsworth, Peter C.; Meade, Donna L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      A limited chemical control tactic known as pinhead square treatment has gained recent Favor as a component of pink bollworm population management. The strategy has economic and ecologic goals of using reduced insecticides early in the season (to include lower rates, half the acreage, and less potent chemistry) in order to reduce later season risk of pink bollworm infestations. This strategy also depends in part on the cultural tactic which results in "suicidal emergence" of overwintering pink bollworms through optimal planting date management. The combination of these tactics has been used in the past to overcome boll weevil populations area-wide. This study is focused on the evaluation of this system as a basis for pink bollworm suppression. Though only preliminary is presented here, it is clear that there are numerous insects impacted by this practice which interact in complex ways to influence pest populations of all kinds. Furthermore, the fate of such a practice in any production system is also influenced by the specific chemical agent used. This experiment details the use of four different classes of insecticide chemistry as well as one bioinsecticide. The experiment has been duplicated in 1993; however, only 1992 data are shown here.
    • Varietal and Nitrogent-level Effects on Sweepotato Whitefly Populations in Cotton

      Watson, T. F.; Silvertooth, J. C.; Tellez, A.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      Four cotton varieties, each differing in leaf pubescence, and three nitrogen (N) levels were investigated for effects upon development of SPWF populations. The N treatments appeared to have no effect upon population development. However, there was a direct correlation of increased SPWF numbers with increased hairiness. Both DPL 5415 and SALCOTIO had significantly lower seasonal means of all stages than did the more hairy varieties of CB1135 and STV453.
    • Whole Season Rotational Pesticide System for Integrated Pest Management for Control of Sweetpotato Whitefly in Cotton

      Akey, D. H.; Henneberry, T. J.; Wuertz, D. A.; Silvertooth, Jeff; USDA, ARS, Western Cotton Res. Lab., Phoenix, 85040; Sundance Farms, Coolidge, AZ 85228 (College of Agriculture, University of Arizona (Tucson, AZ), 1994-03)
      A season long pesticide rotational system for cotton management of Bemisia tabaci (Gennadius) (SPWF) was put in place. The system tried to minimize pesticide impact on midseason build -up of beneficials against SPWF. SPWF thresholds were used to begin use of "potent, efficient" insecticides to stop exponential increase of SPWF in late season. Insecticide class rotation was a key element of the system to prevent insecticide resistance. Comparisons between test blocks and best agricultural practices for rest of field showed that SPWF eggs and large immature of September populations, yields (2.68 bales /Ac), and beneficials were about the same among the blocks. The cotton was free of stickiness in the entire field.