• 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.
    • 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.
    • A Sensor System for Monitoring Cotton Water Status

      Fangmeier, D. D.; Husman, S. H.; Garrot, D. J. Jr.; Yitajew, M.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
    • 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. .
    • 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.
    • Potential Injury to Rotational Crops Following Single or Multiple Applications of Bladex to Cotton 3

      Chernicky, J. P.; Rodgers, C. A.; Heathman, E. S.; Hamilton, K. C.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
    • The Effect on Yield of Cotton Due to Incidence and Severity of Black Root Rot Caused by Thielaviopsis Basicola

      Chapman, M. A.; Hine, R. B.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Incidence of Black Root Rot of cotton and soil inoculum potential of the causal agent Thielaviopsis basicola were monitored throughout the season in two adjacent fields planted in mid April, 1987 in Duncan, Arizona. Mean inoculum potential in Field 1 soil was 65 cfu/g and 20 % of the seedlings were infected. In Field 2 the inoculum potential and percentage of infected plants were 225 cfu/g and 93, respectively. No cortical decay was noted after June 6 in either field. Yields were similar in both fields.
    • Effect of NaCl on the Growth of Germinating Upland Cotton (Gossypium hirsutum L.) Seeds

      Lehle, F. R.; Zegeer, A. M.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Responses to environmental stresses such as excess salinity are difficult to understand if not studied under defined conditions. The objective of this study was to determine if cottonseed radicle and cotyledon growth during germination was affected by exogenous NaCl. Cottonseeds were imbibed in moistened paper toweling for 24 h at 32°C before transfer to an agar media containing selected concentrations of NaCl for an additional 24 h. Radicle linear growth extension was stimulated at low NaC1 concentrations (80 mM), but increasingly inhibited as NaCl concentrations increased from 160 to 400 mM. Radicle and cotyledon fresh weights were increasingly inhibited by NaCl concentrations between 0 and 400 mM. NaCl inhibition of radicle fresh weights was more pronounced than that of cotyledons. We conclude that the inhibitory effects of NaCl can be quantified as reductions in cottonseed radicle and cotyledon growth.
    • Accumulation of Proline in Germinating Cotton (Gossypium hisutum L.) Seeds During NaCl Stress

      Lehle, F. R.; Zegeer, A. M.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      The accumulation of proline (Pro) in plants during NaCl stress may have adaptive significance and the study of this response could reveal a genetic strategy for enhancing NaCl tolerance. Our objective was to determine if the Pro content of germinating cotton seeds is altered by exposure to exogenous NaCl. Seeds were imbibed for 24 h at 32°C before transfer to agar media containing NaCl. After 24 h of NaCl exposure, the Pro contents of radicles and cotyledons were measured using a colorimetric assay. Results showed that Pro contents of both radicles and cotyledons increased as the level of NaCl increased. The bulk of Pro content increases were restricted to the radicle and occurred in the range of NaC1 concentrations from 200 to 400 mM NaCl.
    • 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.
    • Comparison of Three Irrigation Scheduling Methods and Evaluation of Irrigation Leaching Characteristics

      Scherer, T.; Slack, D.; Watson, J.; Fox, F.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Three methods were used to schedule irrigations during 1989 on replicated plots at the Maricopa Ag Center using DPL 90 cotton. This is a continuation of the research initiated in 1988 using the same field The three methods were; a soil water balance model based on historic consumptive use curves, a soil water balance model based on the Modified Penman Equation and daily weather (AZMET), and infrared thermometry using the C.W.S.I. A potassium- bromide conservative tracer was applied at selected sites in the plots to evaluate leaching characteristics. The irrigation scheduling test was again duplicated at the Safford Experiment Station and is presented in another report. Results from this years data indicate that there was no significant difference in yield among the three methods. However, as in 1988 there was a significant difference in water applied with historic consumptive use (ERIE) the lowest and the Penman equation method (CHECKBOOK) the highest.
    • Controlling Purple and Yellow Nutsedge with Postemergence Applications of EPTC

      Chernicky, J. P.; Heathman, E. S.; Rodgers, C.; Hamilton, K. C.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
    • Evaluation of Cotton for Resistance to Pink Bollworm

      Wilson, F. D.; Flint, H. M.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Cotton cultivars and germ plasm lines were screened for resistance to pink bollworm. Sixteen advanced strains were selected for resistance to pink bollworm and/or high yield potential. In a regional early maturing germ plasm lines test, only the short- season check had less seed damage caused by pink bollworm than did the long-season check. Five lines yielded more lint than both checks. In a Pima test, Pima S-6 nectariless had 14% less seed damage than Pima S-6. Seven pink-bollworm-resistant germ plasm lines will be released in the near future.
    • The Influence of ULV Malathion, Applied for Boll Weevil Control, on Other Pest and Beneficial Species in Arizona Cotton Fields

      Leggett, J. E.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
    • 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.
    • 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 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.
    • Cottonseed Treatment Evaluations in Arizona, 1989

      Silvertooth, J. C.; Malcuit, J. E.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)