• Short Staple Cotton Advanced Strains Trial, Safford Agricultural Center, 1994

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Twenty six short staple advanced strains/varieties were grown in a replicated field trial on the Safford Agricultural Center. SureGrow SGX247 was the highest yielding cultivar in the trial with a lint yield of 1628 pounds per acre. The exciting feature of this trial is that the top two swains exceeded the highest yield in the Regional variety trial by 100 to 150 pounds of lint. This is the first time that so many advanced strains were tested in a given year. The site at Safford gives cotton breeders an insight as to how their advanced strains or new varieties will perform in the high deserts of Arizona and New Mexico. HVI data for the varieties in the trial indicate that the average fiber length was greater than 1.11 inches and the average fiber strength was greater than 30 grams/tex.
    • 1993 Parker Valley & Mohave Valley Short Staple Cotton Variety Trial

      Hood, L. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Two short staple cotton variety trials were conducted in the Colorado River Basin. One trial was located in the Parker Valley and one in the Mohave Valley. Ten varieties from various seed companies were entered in each test. Yields varied considerably among varieties and locations. However, these trials among others provides evidence that current variety choices are viable components of Arizona cotton production.
    • Comparative Analysis of Two Sampling Methods for Estimating Abundance of Adult Bemisia tabaci in Cotton

      Naranjo, S. E.; Flint, H. M.; Henneberry, T. J.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      The leaf turn method and the black pan method, two sampling methods for estimating the abundance of Bemisia tabaci (Strain B) on cotton, were compared over a two year period in Maricopa and Phoenix, AZ Both methods were highly correlated with the density of immature stages prior to the use of insecticides, but more poorly correlated after insecticide use began. The two methods were highly correlated with one another, however, leaf turn counts were better predictors of immature infestation. The leaf turn method was also much less variable between individual samplers than the black pan method. Finally, in terms of cost-efficiency it takes, on average, 71% less time to estimate population density with an acceptable precision using the leaf turn method. Based on these criteria, the leaf turn method is a more reliable and efficient technique for estimating adult abundance.
    • Arizona Upland Cotton Variety Testing Program

      Silvertooth, J.; Norton, R.; Clark, L.; Husman, S.; Cluff, R.; Stedman, S.; Thacker, G.; Grumbles, R.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Ten field experiments were conducted in many of the cotton growing areas of Arizona in 1994 for the purpose of evaluating Upland cotton varieties in terms of adaptability and performance. Seven commercial cottonseed companies participated in the program. Two varieties were submitted from each company at each location. Experiments were conducted on grower- cooperator fields in each case. Locations used in the program spanned the range of conditions common to cotton producing areas of the state from about 500 ft. to 4,000 ft. elevation. Results indicated a broad range of adaptability and competitiveness on the part of each of the participating companies and their representative varieties. Each of the companies offers 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.
    • Cotton Leaf Curl Virus, A Threat to Arizona Cotton?

      Nadeem, Athar, 1955-; Xiong, Zhongguo; Nelson, Merritt; Silvertooth, Jeff; Department of Plant Pathology, University of Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A serious virus disease of cotton in Pakistan is distantly related to cotton leaf crumple in Arizona. It is much more destructive on cotton than leaf crumple, and has never been found in the western hemisphere. Cotton leaf crumple in Arizona causes only modestly damaging midseason infections, while leaf curl, has had a major impact on the crop in Pakistan. Modern transportation and the increasing movement of living plants in global trade has resulted in them recent introduction of a similar disease of another crop to the western hemisphere.
    • Establishment of a Whitefly Resistance Documentation and Management Program in Arizona

      Dennehy, T. J.; Simmons, A.; Russell, J.; Akey, D.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Adult whiteflies were collected from six regions of Arizona and evaluated for susceptibility to fenpropathrin (Danitol®), acephate (Orthene®) and endosulfan (Thiodan®), and mixtures of fenpropathrin+acephate curl fenpropathrin+endosulfan. Strong indications of resistance to fenpropathrin, acephate and the fenpropathrin +acephate mixture were documented in some areas of the state. With all populations evaluated endosulfan was consistently the most toxic of the insecticides evaluated (singly) and was highly toxic in mixtures with fenpropathrin. Whitefly resistance to pyrethroid insecticides and especially mixtures of pyrethroid+organophosphate insecticides could have serious ramifications for the prevention of sticky cotton in Arizona. To combat further development of pyrethroid resistance cotton growers will need to reduce the number of pyrethroid treatments made per season.
    • Susceptibility of Arizona Populations of Lygus Bugs to Acephate (Orthene®) and Bifenthrin (Capture®)

      Dennehy, T. J.; Cramer, G. C.; DeBolt, J.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Adult lygus bugs were collected from alfalfa fields in 6 different cotton producing areas of Arizona. The 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 very susceptible to bifenthrin. However, some populations were significantly less susceptible to bifenthrin than were others. Lygus populations with greater than 20% survivorship of 100 μg/ml vial bioassays with bifenthrin should be monitored to provide early warning of future problems with pyrethroid resistance. Resistance of lygus to acephate appeared to be widespread but not uniform in Arizona. While some populations had individuals surviving exposure to vial treatments of as high as 10,000 pg/ml acephate, other populations had no survivors of 1,000 pg/ml treatments. Lygus populations with survivors of 10,000 pg/ml vial bioassays should be considered highly resistant to acephate. Our findings illustrate that resistance levels are often unique from farm to farm, even within the same region. To preserve the long-term usefulness of acephate, where possible, cotton growers should consider using it no more than once or twice per season, on any given field.
    • Cotton Defoliation Evaluations, 1993

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Two field experiments were carried out in representative cotton producing areas of Arizona to evaluate the effectiveness of a number of defoliation treatments on Pima cotton. These experiments were conducted at Coolidge and Marana. The treatments employed principally consisted of relatively new materials available in Arizona, and were compared to current standard treatments. All treatments showed promise in terms of effectiveness and the results provide a basis for use recommendations in 1995.
    • Effect of Soil and Foliar Applied Potassium on Pima and Upland Cotton at Two Arizona Locations

      Galadima, A.; Silvertooth, J. C.; Unruh, B. L.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Due to increasing emphasis and interest being placed on cotton (Gossypium spp.) fiber quality as well as yield benefits associated with potassium (K) fertilization, two studies were conducted in 1994. These studies with those before them were aimed at assessing the agronomic necessity of K fertilization in Arizona cotton production. The locations of the trials included Maricopa Agricultural Center (Casa Grande sandy loam) and Safford Agricultural Center (Pima clay loam). At the Safford location, both Upland (G. hirsutum L., var. DPL 90) and Pima (G. barbadense L., var. S-7) cotton were planted with treatments that included both soil and foliar K applications. The trials at Maricopa Agricultural Center included four foliar K applications over the growing season on Pima (G barbadense L., var. S-7) cotton. The results of the experiments at both locations indicated no lint yield responses to K fertilization by either Upland or Pima cotton.
    • Short Staple Regional Cotton Variety Trial, Safford Agricultural Center, 1994

      Clark, L. J.; Carpenter, E. W.; Hart, G. L.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Fifty five short staple varieties were grown in a replicated field trial on the Safford Agricultural Center. Germain's GC 9033, a variety with the same apparent maturity as DP 90 was the top variety for seedcotton yield but came in third place in lint yield behind two varieties from Australia. Average yields were about 200 lbs per acre lower than 1993, which were about 200 pounds per acre lower than in 1992. HW data for the varieties in the trial are included in this report.
    • Precision Guidance Techniques to Reduce Weed Competition and Production Costs in Cotton

      Thacker, Gary W.; Coates, Wayne E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      The objective of this project is to evaluate the benefits of precision guidance systems as a means of using tillage to kill weeds, and to confine herbicide applications to narrow bands. In cotton, a precision guided close cultivation with a directed spray of MSMA significantly reduced a purple nutsedge stand early on. However this reduction was not significant by the end of the season. For controlling woolly morningglory, the use of a precision guided cultivator equipped with in -row weeding devices resulted in much lower numbers of morningglory weeds, although the differences were not significant at the 95% confidence level. The guidance system kept the implement precisely aligned to the drill rows at a higher speed than was possible with the cooperator's non - precision cultivator. This higher productivity more than offsets the cost of the guidance system and the in-row weeding devices.
    • Telone II® and Temik® Efficacy on Rootknot Nematodes in Cotton

      Husman, S.; McClure, M.; Lambeth, J.; Dennehy, T.; Deeter, B.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Field studies were conducted at four western Maricopa County commercial sites in 1994 to determine whether Temik 15G® would suppress rootknot nematode at low to moderate populations. Three of the experiments were on Upland D +PL 5415 with the fourth on Pima S-6. Sites were chosen based on pre- season sampling with individual field populations ranging from 0.005 (low) - 3.6 (high) rootknot nematode juveniles per cubic centimeter (cc) of soil volume. Each study consisted of four treatments with six replications. The following treatments were used at all test sites: (1) Untreated check, (2) 5 lbs. Temik 15G at planting, (3) 5 lbs. Temik 15G at planting, 15 lbs. Temik 15G sidedressed at pinhead square, (4) 5 gal. Telone 11® pre-plant. Sampling for thrips and lygus was conducted at all test sites to provide insight regarding yield effects resulting from control of insect versus those due to suppression of nematode. There were no significant yield differences between the untreated check and either Temik treatment. However, significant yield increases were measured with Telone versus all treatments at all locations. Insect pressures were minimal in all cases. Temik 15G did not suppress nematode damage at any population level.
    • Nitrogen Management BMPs Parker Valley Demonstration

      Watson, J.; Winans, S.; Sheedy, M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A nitrogen management demonstration was conducted in the Parker Valley in 1994. Grower nitrogen application practices were compared with nitrogen application recommendations based upon pre plant soil samples plus petiole nitrates and plant mapping data. The only significant difference in amounts applied occurred in May, with grower applied rates exceeding recommended rates. Grower rationale for the application was logical, however, it being dependent upon the uncertainty of irrigation timing in June.
    • Multiple Plant Growth Regulator Use on Short Staple Cotton

      Hood, L. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A field trial was conducted during the 1992 & 1993 growing seasons to evaluate the activity of Cytokin and Pic applied alone or in combination to short staple cotton. The Cytokin treatment significantly increased tint yield over the other treatments in 1992. There were no statistically significant seed cotton differences between the non - treated check and any treatment in 1993. Fruit retention remained high throughout 1992 and very high throughout the 1993 season. Under high fruiting conditions, use of a plant growth regulator would not normally be recommended.
    • Effect of Combinations of Accelerate and other Defoliants on Defoliation and Yield of Pima and Upland Cotton

      Nelson, J. M.; Hart, G. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Field studies were conducted at the Maricopa Agricultural center to evaluate the effectiveness of Accelerate when used in combination with other defoliants. In addition, an experimental compound was tested as a boll opener. Air temperatures were very high at the time these tests were conducted and most defoliant treatments caused desiccation of Pima leaves 7 days after treatments were applied. Several treatments did result in acceptable defoliation of Pima cotton 14 days after application. In the upland test, Ginstar used alone resulted in higher defoliation percentages than any combination of defoliants. Boll opener treatments had no effect on boll opening of Pima or upland cotton. In these tests, there were no differences among treatments in lint yield or fiber properties.
    • Irrigation Efficiencies and Lint Yields of Upland Cotton Grown at the Maricopa Agricultural Center, 1994

      Sheedy, Mike; Watson, Jack; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      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 5415 and DP 5816). Nitrogen requirements for the crop were determined using pre -season soil samples and in-season petiole samples with data collected from crop monitoring at weekly intervals. AZSCHED was used as a guide to the irrigation timing and amount of water applied during the season. The irrigation efficiency did not have an effect on the lint yield of the cotton crop regardless of variety, but there was a significant difference in yield between the varieties. Lint yields ranged from 1165 #/acre to 1299 #/acre for DP 5415 and 869 #/acre to 986 #/acre for DP 5816.
    • Bioassay Results in Field Persistence of Two Pink Bollworm Parasitic Nematodes

      Lindegren, J. E.; Henneberry, T. J.; Forlow Jech, L. J.; Burke, R. A.; Silvertooth, Jeff; USDA-ARS, HCRL, Fresno, CA; USDA-ARS, WCRL, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      Steinernema carpocapsae (Weiser) and S. riobravis Cabanillas, Poinar and Raulston applied in the field at the rate of 1 billion nematodes /acre equivalent persisted in the soil for 63 and 6 days, respectively. Persistence of S. riobravis in the field may offer the potential for introduction and permanent establishment of this nematode for pink bollworm (PBW), Pectinophora gossvpiella (Saunders), control in southwestern cotton growing areas.
    • Evaluation of a Feedback Approach to Nitrogen and Pix Application

      Silvertooth, J. C.; Norton, E. R.; Unruh, B. L.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A single field experiment was conducted in 1994 at Maricopa, AZ to compare a scheduled approach (based on stage of growth) versus a feedback approach (based on vegetative status) to both nitrogen (N) and mepiquat chloride (PIX™) applications on Upland cotton (Gossypium hirsutum L.). PIX feedback treatments were based upon fruit retention (FR) levels and height: node ratios (HNRs) according to established baselines. Scheduled PIX applications were made for a total of 1.0 pt./acre over two applications, with feedback PIX treatments receiving a single 0.5 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 four applications and feedback N treatments received a total of 135 lbs. N/acre from three 45 lb. N/acre 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 and a treatment receiving scheduled N and PIX, which were not significantly differencent (P ≤ 0.05) from one another. From a practical standpoint, however, these treatments were very different in terms of the magnitude in differences of fertilizer N and PIX required to produce comparable yields.
    • Timing Initial Post-plant Irrigation Based upon Plant-Water Status

      Steger, A. J.; Silvertooth, J. C.; Brown, P. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A two year study was conducted to determine the optimum timing of the initial post plant irrigation using leaf water potential (LWP) measurements. A short - season Upland cotton (Gossvpium hirsutum L.), variety DPL 20, was planted on 19 April 1993 and 15 April 1994 at the Marana Agricultural Center on a Pima clay loam (Typic Torrifluvent) soil. Treatments, designated Tl , 72, and T3, were such that the initial post plant irrigation would be applied when the midday LWP of the uppermost, fully- developed leaf exposed to full sunlight measured -15, -19, and -23 bars, respectively. All treatments received the same irrigation regime following the initial post plant irrigation. Basic plant measurements, including plant height, mainstem node number, fruit retention, number of nodes above the uppermost white bloom, fresh bloom count within a 166 -ft1 area, and percent canopy cover, were taken weekly from each plot. Soil -water data was collected at 10 inch depth increments, to a depth of 60 in. , from access tubes located in each experimental unit. Yields were 1112, 1095, and 977 lbs lint/acre in 1993 and 1082, 1035, and 964 lbs lint /acre in 1994 for T1, 72, and T3, respectively. Yields were reduced when the midday LWP was allowed to fall below -19 bars, however, reduction was significant (P 5 0.05) only in 1993. At the time of the initial post plant irrigation for each treatment, approximately 83, 62, and 32 % of the total plant available water was present in the upper 60 in. of the soil profile for Ti, 72, and T3, respectively.
    • Pima Cotton Genetics

      Percy, R. G.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1995-03)
      A short season feasibility study, using early maturing Pinta genotypes was conducted for a second season. Four early maturing genotypes, a short season check (P62) and a full season check variety (PS-7) were evaluated in replicated tests under short season and full season regimes. In both 1993 and 1994, most genotypes reached cutout around August 4, with 2759 accumulated heat units. All genotypes were earlier maturing than PS-7, as indicated by plant growth measurements and by sequential harvests. In 1994, the four early maturing experimental genotypes produced yields equal to or slightly better than the longer season cultivar PS-7. No differences in yield occurred between the short season and standard practice management systems in either year. A fiber improvement project was initiated in 1989 with the primary goals of increasing the fiber length and strength potential of Pima cotton. In 1989 the early maturing, short statured Pima strain P62 was crossed to Giza 45 and Giza 70 to transfer the fiber strength of those varieties into a heat tolerant, earlier maturing, productive Pima background. Likewise, P62 was crossed to the Sea Island cultivar St. Vincent V-135 with the objective of transferring the latter cultivar's long fiber length into an agronomic Pima background. Two resulting lines, one possessing high fiber strength and the other possessing high fiber length are planned for release in 1995-96.