• Sweetpotato Whitefly (Bemisia tabaci Gennadius) Control: Field Studies with Insecticides on Cotton in the Imperial Valley, CA

      Chu, C. C.; Henneberry, T. J.; Akey, D. H.; Silvertooth, Jeff; Western Cotton Research Laboratory, USDA -ARS, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      Insecticides and insecticide mixtures were evaluated for sweetpotato whitefly (Bemisia tabaci Gennadius) control on cotton in the Imperial Valley, CA in 1992. Seasonal average number of large immatures was 1.6/cm² leaf disk from plots treated with a mixture of Danitol and Orthene as compared to 4. 5/cm² on leaf disks from untreated control plots. Lint yield was 1232 lbs/ac compared to other treatments which ranged from 551 to 976 lbs /ac.
    • The Effect of Water Stress on Two Short-Season Cultivars of Cotton, Gossypium hisutum L., and the Sweetpotato Whitefly, Bemisia tabaci Genn

      Flint, Hollis M.; Wilson, F. D.; Hendrix, D.; Leggett, J.; Naranjo, J.; Henneberry, T. J.; Radin, J. W.; Silvertooth, Jeff; Western Cotton Research Laboratory, USDA -ARS, Phoenix, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      Deltapine 50 (DP -50) and Stoneville 506 (ST -506), short season cultivars of upland cotton, Gossvpium hirsutum L., were grown under weekly or biweekly irrigation schedules in 0.2 ha plots in a split plot design at Maricopa, AZ. The seasonal average numbers of sweetpotato whitefly eggs and nymphs were 24% greater on leaves of plants irrigated biweekly. The leaves of ST-506 had 26% greater numbers of eggs and nymphs than did leaves of DP -50. Samples of lint from the two cultivars irrigated biweekly had 32 % more sugar than did lint from the cultivars irrigated weekly (weekly = 0.28 ± 0.02% , biweekly = 0.41% ± 0.03% sugar). Our results indicate that the numbers of immature sweetpotato whitefly on cotton plants can be reduced by 47% by selecting a less susceptible cultivar and avoiding plant water stress.
    • Trap Crops as a Component of a Community-Wide Pink Bollworm Control Program

      Thacker, Gary W.; Moore, Leon; Ellsworth, Peter C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      Trap crops were employed against the pink bollworm (PBW) as a part of a community-wide IPM program in Pima County, AZ. Levels of PBW larvae in the early squares of the trap crops were extraordinarily high, indicating that the trap crops were drawing overwintered PBW moths in from wide areas. This concentrated the overwintered moths in small areas where they could be easily and economically destroyed.
    • The Development and Delivery of a Crop Monitoring Program for Upland and Pima Cotton in Arizona

      Silvertooth, J. C.; Brown, P. W.; Malcuit, J. E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      A crop monitoring program has been developed specifically for varieties and environmental conditions unique to Arizona. The monitoring program involves early season development guidelines, growth stage guidelines, and in- season evaluation of crop condition (vegetative /reproductive balance and fruit retention), by use of simple measurements such as height:node ratios (HNR), nodes above the top white bloom (NAWB) counts, and fruit retention estimates from plant mapping. The preliminary work necessary in terms of providing accurate and precise descriptions of the various crop development parameters has been provided through a detailed cotton phenology project conducted over many site years of experimental work. The resultant baselines describing crop development /monitoring parameters have been scaled as a function heat unit (HU, 86/55° F thresholds) accumulations. Application of these baselines have been developed through another facet of the research program to provide a basis for a feedback approach to crop management for inputs such as water, nitrogen (N), plant growth regulators, etc.. The crop monitoring program serves as a fundamental component to an active extension education program being delivered on a statewide basis to all cotton producing areas in Arizona.
    • Irrigation Efficiencies, Nitrogen and Phosphorous Applications, and Lint Yields of Upland Cotton Grown at the Maricopa Agricultural Center, 1992

      Sheedy, Mike; Watson, Jack; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      The computer program AZSCHED, with weather data obtained from AZMET, was used to schedule irrigations for a yield trial of Upland Cotton (DPL 90) at the Maricopa Agricultural Center. Cotton lint yields were compared between plots from eight treatments involving the combination of two irrigation efficiencies (70% and 90%), two nitrogen fertilizer placements (sidedressed and broadcast), and two phosphate fertilizer applications (0#/a and 50#/a). A potassium bromide (KBr) tracer was applied to select areas in each plot prior to the first irrigation. The total amount of fertilizer as nitrogen applied in split applications to both the sidedressed and broadcast plots was 120 #/a. The average amount of water applied to the plots were 33.5" for 70 % efficiency and 26.9" for 90% efficiency. Soil samples from each KBr applied 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. The plots were harvested on October 7, 1992. This year there was no significant difference in lint yield between any of the treatments: irrigation efficiencies, nitrogen placement, or phosphorous application.
    • The Effects of PIX Application Timing on Upland Cotton 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), 1993-03)
      Four commercial scale field studies were conducted in 1991 and 1992 to further evaluate Upland cotton yield and development responses to PIX application timing as a function of cotton growth stage. Treatments imposed in both years intended to further clarify some response trends observed in previous years of field studies. Treatments were all at the maximum label rate of one and one half pints with application timing the main variable. Timing was based on heat unit accumulation and resultant growth stage since date of planting. Two of the four studies resulted in significant lint yield increase of roughly one hundred pounds across all PIX treatments in contrast to the untreated check. The two studies which resulted in lint yield increases both had height:node ratio measurements in excess (vegetative) of previously defined guidelines.
    • Arizona Upland Cotton Variety Testing Program

      Silvertooth, J.; Hood, L.; Husman, S.; Cluff, R.; Stedman, S.; Thacker, G.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      Eight field experiments were conducted across the cotton growing areas of Arizona in 1992 for the purpose of evaluating Upland cotton varieties in terms of adaptability and performance. Five 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 except one, which was conducted on a University of Arizona Agricultural Center. Locations used in the program spanned the range of conditions common to cotton producing areas of the state from about 500ft. to 3,000ft. 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.
    • Effect of Plant Water Status on Defoliation and Yield of Pima Cotton

      Nelson, J. M.; Bartels, P. G.; Hart, G.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      A field study was conducted at the Maricopa Agricultural Center to determine the influence of plant water status at the time of defoliation on the effectiveness of defoliants and yield of Pima cotton. Irrigation termination dates of 4 and 18 September and 2 October were used to achieve different levels of plant water stress at the time defoliants were applied (16 October). Irrigation termination dates tested had no significant effect on lint yield or the effectiveness of defoliants. All irrigation termination dates resulted in defoliation of 80% or higher using a single application of defoliants. At the time of defoliation, CWSI values ranged front 0.59 to 0.80 and plant water potential from -2.0 to -2.9 MPa for the three irrigation termination treatments.
    • Sweetpotato Whitefly Parasites Abundant in Some Cotton Fields During October

      Butler, George D. Jr.; El-Lissy, Osama; Antilla, Larry; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      Surveys of whitefly parasites in cotton showed few or none were present during July and October in some areas, preliminary observations of sticky traps show that large numbers of parasites were present in some fields during October.
    • HVI Lint Quality as Affected by Defoliation Treatments, Marana 1991

      Thacker, Gary; Odom, Phil; Silvertooth, Jeff; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      This study was conducted to determine the effect of various defoliation treatments on the HVI quality of short staple cotton. We compared two applications of sodium chlorate and Accelerate to single applications of Dropp plus crop oil with and without Accelerate. We measured significant differences in percent defoliation and desiccation. We also measured significant differences in the HVI parameters of staple, micronaire, and length.
    • The Arizona Cotton Advisory Program

      Brown, P.; Russell, B.; Silvertooth, J.; Ellsworth, P.; Stedman, S.; Thacker, G.; Hood, L.; Husman, S.; Cluff, R.; Howell, D.; et al. (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      Arizona Cooperative Extension generates and distributes weather -based Planting Date and Cotton Development Advisories for 10 cotton production areas (Marana, Litchfield Pk, Pinal Co., Parker, Safford, Yuma Valley, Dateland and Aguila). Planting Date Advisories are distributed from mid - February through the end of April and stress 1) planting all (particularly full season varieties) cotton varieties according to heat unit accumulations rather than calendar date and 2) the importance of soil temperature to good germination. Cotton Development Advisories are distributed from early May through mid -September and provide updates on crop developmen4 insects, weather and agronomy to growers. The Cotton Advisory Program will continue in 1993 and growers may obtain the advisories by mail (far only in Yuma County only) from the local county extension office or by computer from the AZMET computer bulletin board.
    • Progress on the Use of Trap Crops for Whitefly Suppression

      Ellsworth, P. C.; Meade, D. L.; Byrne, D. N.; Draeger, E. A.; Chernicky, J. P.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      In 1992, a repeat of a trap -cropping experiment was conducted for the suppression of sweetpotato whiteflies in Pima (S-6) cotton (see Ellsworth et al. 1992). The 1991 experiment showed some promise, but was characterized by low to moderate and later infestations of whiteflies than was desired. The 1992 experimental design (land area = 9.5 acres) was modified to accomplish three improvements: 1) the cotton crop area was doubled in size to 8 rows by 50 ft to improve the ratio of crop to trap area, 2) a fourth treatment was added to form a Latin square design which consisted of cotton plots surrounded only by bareground (i.e., no trap crop): the other three were surrounded by Wright groundcherry that was untreated or treated with 1X or 2X rates of soil-applied aldicarb, and 3) melons (1 row X667') were late planted between blocks to ensure locally abundant whiteflies during the time of the test. The melons were watered regularly in order to retain whiteflies until the start of the test. Early groundcherry establishment was variable and later compromised by insufficient water. This prompted later than usual flushes of groundcherry growth and delayed canopy development. This fact coupled by the intense level of whitefly movement following melon dry -down effectively overwhelmed the insufficiently developed trap crop. Aldicarb was applied on two dates (7/29 & 8/15), and whiteflies were sampled from all plots five times through August. The sampling data are preliminary at this point, but several observations were apparent: 1) the groundcherry trap crop was insufficiently developed to protect the Pima crop, 2) the addition of melons to the system dramatically increased the ,cumbers of locally abundant whiteflies, 3) maintaining the melons in good condition (i.e., well- watered) effectively retained whiteflies in the melons until dry-down, 4) upon dry-down, the melons released overwhelming numbers of adult whiteflies which could not be suppressed on the groundcherry trap crop before reaching the adjacent cotton, 5) the groundcherry was still selectively attractive to the whiteflies (relative to cotton), but was insufficiently developed w trap and retain the huge numbers of dispersing whiteflies, 6) soil - applied aldicarb did accomplish some degree of control of whiteflies on the groundcherry plants, but was inadequate in the face of the tremendous immigration of whitefly adults, 7) the intense whitefly pressure ultimately killed the majority of immature groundcheny plants with the aldicarb-treated plants lasting somewhat longer than the untreated plants, and 8) the yield and quality of the adjacent, late -planted Pima crop was commercially unacceptable and judged to be virtually a total loss. The failure of this implementation of the trap -cropping concept does not preclude the possibility that a better implementation would have succeeded; however, the observation that melons in close proximity to the test area dramatically changed the number of locally dispersing adult whiteflies cannot be denied. It would seem unlikely that a suitable trap crop system could be developed where such an intense proximate source and near instantaneous release of thousands of whiteflies (i.e., at dry-down of melons) is occurring.
    • Sweetpotato Whitely Control on Cotton by Treating Only the Field Edges

      El-Lissy, Osama; Antilla, Larry; Butler, George D. Jr.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      The edges of one of each of five pairs of long staple cotton fields were treated for sweetpotato whiteflies. Treated fields had 61% fewer eggs and 53% fewer nymphs than untreated fields. Adult populations were reduced 64% in the treated fields at the edges. In the center of treated fields adult populations remained low and unchanged but in untreated fields there was a 70% increase. According to minicard tests, cotton from treated fields was not sticky but cotton from untreated fields was sticky. Thus, populations of whiteflies and their damage can be significantly reduced by treating only the periphery of cotton fields at the onset of infestation. The treating of only 12 to 15% of the acreage greatly reduces costs and preserves the untreated center for beneficial insects.
    • Cotton Response to Applications of PIX, 1992

      Silvertooth, J. C.; Malcuit, J. E.; Hood, L.; Husman, S. H.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      Four field experiments were conducted in 1992 in Arizona to evaluate cotton crop response to several treatment regimes of multiple applications of PIXTM (an anti - gibberellicacid plant growth regulator). Treatment regimes used in 1992 employed higher rates of PIX/acre /application and extended times of applications later into the fruiting cycle than earlier experiments in 1988 through 1991. Some treatments used exceeded currently labeled maximum use rates in an attempt to evaluate the possible need of increasing maximum rates. Similar to earlier experiments, results in 1992 demonstrated the ability of some PIX treatments to significantly reduce plant height, relative to the untreated check treatments. Excellent fruit retention levels were experienced in each experimental site in 1992, irrespective of PIX treatments. Lint yield results revealed significant differences (P ≤ 0.05) between several selected treatments at two of the locations in 1992.
    • Drought Tolerance in the Progeny of Interspecific Cotton Hybrids

      McDaniel, R. G.; Dobrenz, A. K.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      The F2 and F3 progeny of interspecific cotton crosses were evaluated under field conditions. The plants were maintained under drip irrigation with stress applied by withholding water during plant development and early flowering periods. Physiological and biochemical plant responses were measured throughout the growing season on an array of representative plants from the field population. Considerable variability was found to exist among these progeny for all traits measured in both years of the present study. Responses of parental controls were quite consistent for both seasons.
    • Defoliation of Pima Cotton at the Safford Agricultural Center, 1992

      Clark, Lee J.; Carpenter, Eddie W.; Odom, Philip N.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      Three defoliation studies were performed on Pima cotton at the Safford Agricultural Center in 1992. One tested two different formulations of Dropp with various adjuvants. The second compared experimental material SN597 with other common defoliants. The third compared SN597 at different rates in a late application. At 14 days after application SN597 dropped 97% of the leaves compared to 37% for sodium chlorate. All of the combinations dropped leaves much more efficiently than chlorate.
    • Upland and Pima Cotton Response to Soil and Foliar Potassium at Three Arizona Locations

      Unrah, B. L.; Silvertooth, J. C.; Clark, L. J.; Nelson, J.; Malcuit, J. E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      Due to a limited information describing the response of cotton (Gossvpium spp.) in Arizona to K fertilization, three studies were conducted in 1992 with the objective of evaluating the response of cotton crop growth and lint yield to soil and/or foliar applications of K fertilizer. The locations of the trials included the Safford Agriculture Center (Pima clay loam), Maricopa Agriculture Center (Casa Grande sandy loam), and a site located near Coolidge, AZ on a Mohall sandy loam soil. All irrigation, pest management, and fertilization inputs (other than K) were provided on an as- needed basis throughout the season. Routine plant measurements and plant mapping analyses were carried out at each location on regular intervals throughout the season. At the Safford location both Upland (G. hirsutum L., var DPL 90) and Pima (G. barbadense L., var S-6) cotton were planted with treatments including soil and foliar K applications imposed in a factorial arrangement. All soil K applications were broadcast and preplant incorporated using K₂SO₄ as the K source at rates of 0, 200, and 400 lbs. K₂O/acre. Four 4.6 lbs K₂O /acre foliar applications of KNO₃ were applied at 1626, 2016, 2326, and 2510 heat units after planting (HUAP). The trial at the Maricopa Agriculture Center included four foliar K applications over the growing season applied to Pima cotton (S-6) at 2427, 2762, 3200, and 3515 HUAP. The six foliar treatments included rates which ranged from 0 to 37 lbs. K₂O /acre using KNO₃ as the K source. Treatments were arranged over the experimental area in a randomized complete block design with five replications. At Coolidge all K treatments were band-applied to the soil at a depth of 8 in. using two shanks per row, preplant. The treatments were 0, 218, 436, and 654 lbs. K₂O /acre using K₂SO₄ as the fertilizer source. Upland cotton (STV KC311) was planted and treatments were arranged in a randomized complete block design with four replications. Results from all three trials indicated no differences among any of the treatments (including soil verses foliar and unfertilized treatments). All of the plant measurements taken for all the locations reveal crop growth resulting in excellent fruit retention without vegetative growth (i.e. height-to-node ratios within the long -term 95% confidence intervals for both Upland and Pima cotton. This indicates ample nutrient demand so that if available soil K is inadequate to meet crop needs, deficiency symptoms and reduced yields should occur. No visual deficiency symptoms were detected for any treatment in the experiments (all locations). All plots experienced vigorous and wellbalanced growth and development throughout the growing season. The results of these K fertility experiments supports current University of Arizona recommendations that unless exchangeable K is less than 150 ppm, crop response is not likely, although an exact critical level for exchangeable K is still lacking.
    • Nitrogen Management Experiments for Upland and Pima Cotton, 1992

      Silvertooth, J. C.; Clark, L. J.; Malcuit, J. E.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      Two field experiments were conducted in Arizona in 1992 at two locations (Maricopa and Safford). The purposes of the experiments were to validate and refine nitrogen (N) fertilization recommendations for both Upland and Pima cotton. The experiments each utilized N management tools such as pre-season soil tests for NO₃⁻-N, in-season plant tissue testing (petioles) for N fertility status, and crop monitoring to ascertain crop fruiting patterns and crop N needs. Results at both locations revealed a strong relationship between the crop fruit retention levels and N needs for the crop. This pattern was further reflected in final yield analysis as a response to the N fertilization regimes used. The effects of N fertility levels were evident in crop maturity and its relationship to lint yields.
    • Long and Short Staple Cotton Variety Trial, Safford Agricultural Center, 1992

      Clark, L. J.; Carpenter, E. W.; Nelson, J. M.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      Thirty six short staple varieties and thirteen long staple varieties were grown in a replicated field trial on the Safford Agricultural Center in Graham county. Stoneville 324 was the highest yielding short staple variety in the trial with a yield of 4733 pounds per acre of seed cotton. The average yields of short staple varieties was greater than in 1991. Long staple cotton did not fare as well with the weather as did the short staple. The yield of S-6 was about 100 pounds of seed cotton less than in 1991. The good news is that other long staple varieties are being developed that can out yield S -6 in the high desert area. O & A Pima was the highest yielding variety with a yield that exceeded S-6 by about 500 pounds of seed cotton per acre. S-7 followed closely behind O & A Pima 4 and both matured quicker than S-6. Heat unit data from the past couple of years are given in this report along with the average heat unit accumulation.
    • Short Staple Variety Demonstration, Graham County, 1992

      Clark, Lee J.; Cluff, Ronald E.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1993-03)
      Twelve upland cotton varieties were compared in an on farm trial in Graham county. The highest yielding variety was Stoneville 324, a relatively new semi-smooth- leafed variety from Stoneville with fiber qualities that approach those of DPL 90. Stoneville 324 yielded 4226 pounds of seed cotton with HS Sal 10 following closely behind at 4158 pounds per acre.