• Early-season Cotton Square Removal with Ethephon and Initiation of Pink Bollworm Infestations

      Henneberry, T. J.; Bariola, L. A.; Chu, C. C.; Meng, T. Jr.; Deeter, B.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Ethephon applied at rates of 0.50 or 0.75 lb AI/acre removed early-season squares and delayed initiation of pink bollworm, Pectinophora gossvpiella (Saunders) infestations and reduced the number of infested bolls on early-season fruiting branches, without affecting yield except for ethephon at 0.751b AI /acre at one location. Higher rates of application reduced yields. In most cases, ethephon treatments delayed flowering but plants compensated for removal of early- season squares and equalled or surpassed accumulated flowering of untreated control plants later in the season.
    • Effect of Date of Planting and Irrigation Termination on Pink Bollworm Populations in Pima and Upland Cotton

      Terry, L. I.; Silvertooth, J. C.; Summers, C.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Field experiments conducted in 1989 comparing effects of planting date and irrigation termination date on pink bollworm in both in- season and overwintering infestations indicated different responses depending upon the location and type of cotton. Tests were located at: Yuma Agricultural Center; Marana Agricultural Center; and Maricopa Agricultural Center. Infestations at Yuma ranged from 0% at early flowering to 80% infested bolls prior to harvest. Marana had equally high infestations at the end of the season, while Maricopa had the lowest infestations ranging from 2% to 5% for Pima and 3 %-17% for Upland. Planting date or species of cotton did not affect early infestation. Data comparing plots for overwintering infestations are still being evaluated. Continuous insecticide treatments were made at all locations after squaring began.
    • 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.
    • Effect of Irrigation Termination Date on Defolation and Yield of Upland Cotton for Short-Season 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 influence of plant water stress on the effectiveness of defoliants and yield of short season cotton. Irrigation termination dates of 11, 18 and 24 August were used to achieve different levels of water stress at the time defoliants were applied (1 September). Irrigation termination dates had little effect on the response of cotton to defoliants. Def-6 at the lowest rate tested, 0.75 lbs a.i./A, was less effective in defoliating cotton with a 24 August irrigation termination date than cotton terminated earlier. Dropp resulted in higher defoliation percentages and 30% fewer unopened bolls at harvest than Def-6. Although the irrigation termination dates provided a range of CWSI values at the time of chemical termination, no clear relationship was found between CWSI values and defoliation percentages. Short season cotton (149 days) produced 3.2 bales of lint/A compared to 4.4 bales for a full-season crop (208 days).
    • 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.
    • 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.
    • 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.
    • Effects of Date of Planting on the Yield of Four Cotton Varieties at Yuma, Arizona

      Malcuit, J. E.; Howell, D. R.; Silvertooth, J. C.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      A field experiment was conducted in Yuma, Arizona, to evaluate the effects of planting date on cotton yields. One Pima and the Upland cotton varieties were planted on four dates from 23 February to 5 April. DPL-90 produced the highest yield (1760 lbs lint acre⁻¹) at the second planting date (9 March). The lowest yields, for all varieties, resulted from the latest planting date (5 April). The greatest reductions in yield when comparing an early planting date to the latest planting date, were observed for DPL-90 and Pima S-6. However, in spite of the reduction in yield, DPL-90 was the highest yielding variety at the latest planting date.
    • 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.
    • 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.
    • Evaluation of Date of Planting and Irrigation Termination on the Yield of Upland and Pima Cotton

      Silvertooth, J. C.; Watson, T. F.; Terry, L. I.; Malcuit, J. E.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Three field experiments were conducted in 1989 in Arizona to evaluate the response of Upland and Pima cotton to two dates of planting and two dates of irrigation termination. Planting dates ranged from as early as 22 February in the Yuma Valley (150 ft. elevation) to 4 May at Marana (2,000 ft. elevation). Dates of irrigation termination ranged from 27 July in the Yuma Valley to 8 September at Maricopa and Marana. Based upon the final lint yield, planting date provided a significant main effect within two of the three experimental locations (Yuma Valley and Marana). At the Maricopa location, there was a significant effect on yield due to date of irrigation termination with both 30-inch- and 40-inch-row Upland cotton experiments, resulting in differences of 167 and 157 lbs. lint /acre, respectively, by extending two irrigations (approximately 12 acre inches) past 10 August to 8 September. The Pima experiment at Maricopa was similar with a significant (P <0.05) response to two additional irrigations (approximately 12 acre-inches) of 184 lbs. lint /acre. Return from additional lint yield must be considered against additional costs (water, insect control, etc.), as well as possible quality losses from insect infestations.
    • 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.
    • 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.
    • 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)
    • Insecticide Efficacy on Beet Armyworm Infestations in Open and Closed Cotton Flowers and Effects of Flower Infestation on Boll Abcission

      Akey, D. H.; Henneberry, T. J.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      In 1988 severe beet armywonn (BAW) infestations resulted in damaged cotton flowers and foliage. Some insecticide applications failed to eliminate larvae in the flowers because applications were applied before the flowers opened. Applications made after flowers were open were more effective. In 1989, tests were conducted to define further these results. Karate™ applied when cotton flowers were open achieved 90% control compared to 9% when flowers were closed in one test, and 97% compared to 13 %, respectively, in a second test (P\0.01). A higher percentage (18 %) of cotton bolls was shed on day 7 following flower infestations than were shed (6 %) when flowers were not infested.
    • 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.
    • Irrigation Scheduling on Long and Short Staple Cotton, Safford Agricultural Center, 1989

      Clark, L. J.; Carpenter, E. W.; Scherer, T.; Slack, D.; Fox, F.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Two irrigation scheduling trials were performed in 1989, one for short staple and one for long staple. Yields in the trials were very good with the best treatments yielding over 1700 and 1600 pounds of lint per acre for DP 90 and S-4 respectively. The treatment using Infrared thermometry was the best overall treatment in the short - staple trial, with the highest yield, the highest percent first pick, the shortest plants, the lowest water use and the highest water use efficiency. The two computer methods were very close to the IR treatment in yield and percent first pick, but grew taller plants with more water and were not as efficient with their water use. The trial on long staple cotton was encouraging in that reasonable yields were obtained using short-staple parameters. The computer model using AZMET data yielded significantly lower than the other treatments, indicating that we need to refine the evapotranspiration crop coefficients.
    • Nitrogen Management in Irrigated Cotton

      Silvertooth, J. C.; Clark, L. J.; Carpenter, E. W.; Malcuit, J. E.; Else, P. T.; Doerge, T. A.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      Two field experiments were conducted in 1989 in Arizona to compare several methods of nitrogen (N) management in Upland and Pima cotton. Standard preplant, preplant plus sidedress, and use of soil and petiole analysis for NO₃⁻-N were the basic methods of N fertilization management compared. A nonfertilized check treatment also was included with the N management treatments, which were arranged in a randomized complete block design in each experiment. Preseason soil samples and a series of in- season petiole samples were taken for all treatments and analyzed for NO₃⁻-N. The concentrations of NO₃⁻-N in the petioles reflected the boll load obtained and the crop fruiting patterns as well as the N fertilization patterns in the respective treatments. Final lint yield analysis revealed distinct differences among the treatments imposed at the Maricopa location but no statistically significant differences at the Safford location.
    • Pima Cotton Genetics

      Percy, R. G.; Turcotte, E. L.; Silvertooth, Jeff; Bantlin, Marguerite (College of Agriculture, University of Arizona (Tucson, AZ), 1990)
      In an investigation of the genetic diversity and structure of Gossvpium barbadense L. it was determined that northwestern South America was the species' center of variability and probably the species' center of origin. Cultivars of the species were found to possess as much genetic variability as the center of variability. Cultivar variability was due in large part to introgression with G. hirsutum. Studies of interspecific hybrid performance revealed that development of G. barbadense parents could significantly affect the plant height, earliness, and yield of the resulting hybrids. Environment significantly affected hybrid performance and could enhance or obscure any beneficial effects of hybrid parent selection. A conversion program to convert photoperiodic short-day flowering tropical accessions to day neutrality continues. Preliminary results from inheritance and linkage studies of a male sterility factor and a foliar mutant indicate that both are single gene, recessive traits. No linkages between the male sterility factor and 21 marker traits were found.