• Regional Variety Tests

      Pegelow, E. J. Jr.; McAlister, A. C.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Regional variety tests were conducted at Maricopa, and Marana Agricultural Centers in continuing cooperation with the beltwide testing program. The national standards included in this test were Coker 139, Deltapine 50, and Paymaster 145. Lint yields for each variety, at both locations, are given in Table 1.
    • ABA and Auxin Contents of Squared and Flowers in Relation to Water Deficit Stress and Subsequent Young Boll Shedding

      Guinn, G.; Brummett, D. L.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Water deficit increases boll shedding. Large squares, however, are much less likely to shed, possibly because they contain high concentrations of free and total auxin (indole-3-acetic acid or IAA). Our previous research indicated that much of this IAA disappears by the time the squares open as flowers and the IAA content remains low for about four days after anthesis. If water deficit decreases the IAA content, or increases the ABA conten4 of squares and flowers, then water deficit before flowering could have a carry-over effect and increase the shedding rate of young bolls that subsequently develop from them. In field plots, water deficit increased the ABA content of flowers as much as 66 %. Water deficit first decreased and later increased the concentrations of free and total IAA in squares that were analyzed about three days before anthesis. Flowers contained much less IAA than squares. Despite pronounced effects of water deficit on the IAA content of squares it is unlikely that it had any carry-over effect on the free IAA content of young bolls that subsequently developed from them. Water deficit slightly increased the total IAA content of flowers, but had no effect on their free IAA. Because water deficit increased the ABA content but did not decrease the IAAA content of flowers, any carry-over effect of water deficit on young boll shedding might have been from changes in ABA but not from changes in IAA before the young-boll stage.
    • A Study of PIX Rates across CaZa and Triggrr on Long and Short Staple Cotton, Safford Agricultural Center, 1989

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      An experiment was designed to test seven treatments of PIX on both short and long staple cotton. The treatments included single applications of 1/2- and 1-pint rates and multiple applications of 1/8- and 1/4-pint rates. Because of the exceptionally good growing season with lots of early heat units, both short- and long-staple plants set fruit early, which limited their vegetative growth naturally without the need for FIX. Yields were high with lint production over 1800 and 1400 pounds of lint for short and long staple, respectively. Plant mapping also was performed on each treatment.
    • Influence of Multiple Applications of PIX on Long and Short Staple Cotton, Safford 1989

      Clark, Lee J.; Carpenter, Eddie W.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      A four-by-four factorial experiment was performed on the Safford Agricultural Center to determine if CaZn, Foliar Triggrr or Soil Triggrr would cause increases in lint yields on short or long staple cotton. Four levels of PIX were used to see if there would be any interaction between PIX and the other materials. The results in 1989 showed that CaZn and the Trier products did not increase yields, the levels of PIX did not increase yields and there was no interaction between them. Very favorable weather conditions and good crop management kept plants from growing vegetative and prevented crop stress, thus reducing the opportunity for the plant growth regulators to increase yields. Yields were excellent with over 1700 and 1600 pounds of lint per acre for short and long staple cotton, respectively.
    • Short Staple Variety Demonstration, Maricopa Agricultural Center, 1989

      Malcuit, J.; Silvertooth, J.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      A short staple variety trial was conducted on the demonstration farm, at the Maricopa Agricultural Center in 1989. Twenty varieties, received from various seed companies, were entered into the test. Results from the analysis showed significant differences among varieties with no observable performance trend in terms of maturity types (long or short season). The lint yields in this test ranged from 4679 to 3353 lbs. acre⁻¹ for DPL90, and S55 respectively.
    • Short Staple Variety Demonstrations, Pinal County, 1989

      Malcuit, J.; Stedman, S.; Silvertooth, J.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Short staple variety demonstrations were conducted in Pinal County in 1989 at the Prechel and Benedict Farms near Coolidge Az. Twelve varieties were included in the demonstration at Prechel Farms. Results from the analysis showed significant differences among varieties. Seedcotton yields in this test ranged from 4826 to 2844 lbs. acre⁻¹ for STV BR-110 and S-55 respectively. Seven varieties were included in the demonstration at Benedict Farms. Results from the analysis showed significant differences among varieties. Seedcotton yields in this test ranged from 4127 to 3530 lbs. acre⁻¹ for STV BR-110 and DP-50 respectively.
    • Effect of Harvest Date on Aflatoxin Contamination in the Yuma Valley

      Cotty, P. J.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Experiments were performed at the Yuma Valley Agricultural Center to determine how timely harvest of cotton may affect aflatoxin contamination of cottonseed As the cotton was held in the field between the final irrigation and harvest, the quantity of aflataxin in the crop increased. Significant reductions in aflatoxin contents of seed were realized by harvesting in early September.
    • Planting Date and Susceptibility to Pink Bollworm

      Brown, P.; Huber, R.; Moore, L.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      The susceptibility of cotton to spring emergence of pink bollworm (PBW) was evaluated for a variety of planting dates in Pinal Maricopa, LaPaz and Yuma counties using historical climate records and heat-unit-based models that predict PBW emergence and cotton development. Early planted cotton proved most susceptible to the PBW emergence, however, cotton type (shoe vs. long staple) and springtime weather conditions both played an important role in overall susceptibility.
    • Short Staple Demonstrations, Graham County, 1989

      Clark, Lee. J.; Cluff, Ronald E.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Short- staple variety trials were grown in two locations in Graham County in 1989. Exceptional weather conditions, coupled with good management practices, provided record cotton yields in the Safford valley. Delta Pine 77 was the highest yielding variety in the Thatcher location with a yield of 1740 pounds of lint per acre. An experimental acala from New Mexico came in second in this triad ahead of Delta Pine 90. Delta Pine 90 was the highest yielding variety in the Eden area with a yield of 1196 pounds per acre. Data on percent first pick plant height and plant populations are presented for each variety in each location. Graphs of heat units received each day throughout the growing season at the AZMET station on the Safford Agricultural Center are presented for 1988 and 1989.
    • Defolation of Pima Cotton, 1989

      Silvertooth, J. C.; Howell, D. R.; Thacker, G.; Stedman, S. W.; Winans, S. S.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Four field experiments were carried out in several representative cotton producing areas of Arizona to evaluate the effectiveness of a number of defoliation treatments on Pima cotton. Variable conditions were encountered among the experimental locations in 1989 for treatment comparisons. However, it appears that consistencies in the effectiveness of several treatments for Pima defoliation offer a better basis for recommendations across the state.
    • Interaction of Pima Cotton Defoliation and Crop Water Stress Index

      Silvertooth, J. C.; Stedman, S. W.; Tollefson, J.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      A single field experiment was conducted in 1989 to evaluate the relationship of crop water status on Pima cotton defoliation by use of a crop water stress index (CWSI) as estimated by infrared thermometry. The entire study area was given the last irrigation uniformly on 24 August, and 20 row plots were outlined for the arrangement of three treatments in a randomized complete block design with three replications. Treatments consisted of making defoliant chemical application at three different targeted CWSI levels (0.40, 0.60, and 0.85). All defoliant treatments consisted of Dropp plus Accelerate (0.4 lb. and 1.5 pt. of material/acre, respectively) applied with a ground rig applicator. Results indicated no distinct advantage in terms of percent defoliation as a function of lower CWSI levels at which defoliants were applied. The defoliations made at 0.40 CWSI did result in more regrowth after 14 and 21 days. It appears from this test that Pima plants will defoliate satisfactorily with proper chemical treatments up to CWSI levels of 0.80. Further desiccation of the crop results in very erratic CWSI readings, resulting in difficulties in applying this technique to defoliation management. It does appear, though, that Pima cotton defoliation can be accomplished when CWSI readings are between 0.5 and 0.8 without substantial regrowth problems, providing precipitation or irrigation events do not occur.
    • Effect of Plant Nitrogen Status on Effectiveness of Pix and Defoliants for Short-Season Cotton Production

      Nelson, J. M.; Briggs, R. E.; Hart, G.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      A field study was conducted at the Maricopa Agricultural Center to determine the effect of nitrogen fertility level on the effectiveness of PIX and defoliants for short- season - cotton production. Increasing the nitrogen fertility level from 90 lbs N/A to 240 lbs N/A increased lint yields from 2.23 to 3.14 bales/A, respectively, in a 157-day growing season. FIX treatments did not promote earliness, and resulted in yield reductions. Increasing the application rates of Dropp from 0.1 to 0.2 lbs a.i./A and Def-6 from 0.75 to 1.13 lbs a.i./A resulted in increases in leaf drop. There was a significant linear decrease in the effectiveness of defoliants as the petiole NO3 N content increased from 850 to 2450 ppm.
    • Defoliation Research on Upland Cotton at the Maricopa Agricultural Center in 1989

      Nelson, J. M.; Briggs, R. E.; Hart, G.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      A field study was conducted at the Maricopa Agricultural Center to evaluate the effectiveness of experimental defoliants and adjuvants on DPL 90cotton. None of the defoliation treatments tested were effective in September when air temperatures were above 100° F. Several chemicals gave 80% or higher defoliation in early October when temperatures were in the low 90s. The experimental defoliant SN 597 NA218 appears to have promise as a late-season defoliant for DPL 90 cotton.
    • PIX Multiple Application Evaluations in Arizona on Upland and Pima Cotton, 1989

      Silvertooth, J. C.; Malcuit, J. E.; Howell, D. R.; Farr, C. R.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
    • Effects of Irrigation Termination Date on a Medium Maturity Type Upland Cotton

      Silvertooth, J. C.; Malcuit, J. E.; Stedman, S. W.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      A single field experiment was conducted in 1989 on a grower cooperator field to evaluate the response of a medium maturity type Upland cotton (DPL-50) to three dates of irrigation termination. The crop was planted 20 April and managed uniformly in all respects until 2 August when the earliest irrigation termination treatment was imposed. The dates of the second and final irrigation terminations were 17 August and 1 September, respectively. With each subsequent irrigation, the respective plots received an additional six acre inches of water (approximately). Harvest results revealed no significant (P <0.05) differences in lint yield due to irrigation termination treatments. Overall mean lint yield for the experiment was 1,228 lbs. cotton lint/acre, the experimental coefficient of variation (CV) was 11% and the observed significance level (OSL) was 0.34.
    • Upland and Pima Cotton Response to Banded Phophate Fertilization

      Silvertooth, J. C.; Malcuit, J. E.; Doerge, T. A.; Thacker, G. W.; Stedman, S. W.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Four field experiments were established in Arizona in 1988 and six in 1989 to evaluate the effects of banded phosphorus (P) fertilizer on cotton. Experiments each year involved both Upland (Gossvpium hirsutum L.) and American Pima (Q. barbadense L.). Banded applications of P fertilizer were made with placement of the concentrated band of fertilizer 6 in. below and 3 in. to the side of the zone of seed placement. Fertilizer sources of P₂O₅ were with 10-34-0 or 16-20-0. At all locations, a series of rates of applied P₂O₅ were established as the treatment variables, including a check (0 lb P₂O₅/acre). Rates of applied P ranged from 0 to 90 lb P₂O₅/acre, at increments of approximately 30 lb. P₂O₅/acre. In all cases, treatments in the field were arranged in a randomized complete block design with four replications. Plant measurements for plant height, flower numbers per unit area, number of mainstem nodes, and nodes to the first fndting branch were initiated by the fifth true leaf stage to evaluate plant response in terms of growth and development. Plant tissue samples were also taken at several stages of growth from each experiment throughout the growing season. Tissue samples consisted of petioles and leaf blades from the uppermost fully developed leaves. Petioles were analyzed for extractable PO₄-P and leaf blades for total P. Lint yield measurements also were taken. With the exception of one of the experimental locations in each year, no statistically significant differences (P≤0.05) were found among any treatments for any of the plant growth parameters. The same was true with regard to petiole PO₄-P and leaf blade total P levels measured. No significant differences among treatments were found for either Upland or Pima cotton with regard to lint yield in 1988 or 1989.
    • A Comparison of Three Cotton Tillage Systems

      Coates, W. E.; Thacker, G. W.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Two alternative tillage systems used significantly less energy than conventional tillage. The Sundance system used the least energy, averaging 35 horsepower-hours per acre (Hp-hr /ac), the Uprooter Shredder-Mulcher (USM) was intermediate at 50 Hp-hr /ac, and the conventional system used the most energy at 69 Hp-hr /ac. These energy savings translated directly into cost savings of about the same proportions. The USM and Sundance systems can plow down and prepare the next seedbed in about one-half the time that conventional tillage requires. In the two years of testing we could not measure any significant differences in cotton yield. So far, we have not found any significant differences in soil compaction.
    • Exogenous L- and D-Proline Does Not Reduce NaCl Inhibition of Radidle Growth of Germinating Cotton (Gossypium hirsutum L.) Seeds

      Lehle, F. R.; Zegeer, A. M.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      The adaptive significance of proline (Pm) accumulation in cotton seeds can be assessed by determining if NaCl tolerance is influenced by changes in the Pm level of the seed. The objective of this study was to determine if exogenous L-Pro and D-Pro reduce NaCl inhibition of radicle growth of germinating cotton seeds. Seeds were imbibed for 24 h at 32°C before transfer to agar medium containing either Pro, NaCl or mixtures of both. Results indicate that exogenous Pro increases the Pro contents of cotton seed radicles and cotyledons to a similar extent. Such increases are independent of whether L- or D-Pro is fed exogenously. Results also show that exogenous Pro does not significantly reduce NaCl inhibition of radicle growth in germinating cotton seeds. .
    • Gossyplure-baited Pink Bollworm Male Moth Trap Studies

      Chu, C. C.; Henneberry, T. J.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Gossyplure, the pink bollworm, Pectinophora gossvpiella (Saunders), sex pheromone is an excellent tool as a bait in traps for detection, survey, research and monitoring male moth populations. We studied the within - and between-seasonal changes of pink bollworm male moth catches in gossyplure-baited live traps installed in cotton fields each year from 1981 to 1988. Seasonal average number of male moths caught varied from 14/trap/night in 1982 to 148 /trap /night in 1981. Male moths caught/trap/night were highly correlated with the minimum air temperatures. The number of male moths caught from March to June were significantly correlated with those caught from July to August, indicating that early spring trapping can be used to identify potential problem fields.
    • Sweetpotato Whitefly Populations in Cotton Genotypes at Poston, Arizona in 1988

      Butler, G. D. Jr.; Henneberry, T. J.; Perkins, H. H. Jr.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Studies were conducted to identify potential sources of cotton germ plasm resistant to sweetpotato whitefly (SPW), Bemisia tabaci (Gennadius). Numbers of adult SPW sampled using black pan and vacuum methods showed reduced numbers of SPW on GC-EXP-7007 experimental variety vs. all other entries. However, numbers of SPW pupae on leaf samples in most cases were not different. Pima P-62 had the high numbers of SPW adults per blackpan sample, and highest number of pupae/leaf sample.