• Agronomic Evaluation of Transgenic Cotton Varieties

      Moser, H. S.; McCloskey, W. B.; Silvertooth, J. C.; Silvertooth, Jeff; Department of Plant Sciences, University of Arizona (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      Four field tests were conducted at three Arizona locations in 1999 to evaluate the performance of transgenic cotton varieties in Arizona. We included a total of 34 varieties in one or more of these tests. Across locations and varieties, Bollgard (BG) and stacked BG and Roundup Ready (BGRR) varieties produced about 7 to 8% greater lint yields than the conventional varieties from which they were derived. Across all varieties and all tests, the average lint yield of the Roundup Ultra sprayed RR or BGRR treatments was 1569 lb./A, while the average yield of the unsprayed RR or BGRR treatments was 1580 lb./A. Roundup Ready (RR) varieties produced lint yields similar to the conventional varieties with a couple of exceptions. Roundup Ready varieties tended to be taller and more vigorous than the conventional parent. Transgenic varieties were often different from the conventional parent in one or more traits, such as fiber quality, lint percent, boll weight, or maturity, but the variation was not associated with a particular transgene.
    • Arizona Upland Cotton Variety Testing Program, 1999

      Moser, H.; Clark, L.; Husman, S.; Clay, P.; Silvertooth, J.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      Each year the University of Arizona conducts on-farm variety trials across the state to evaluate the performance of upland cotton varieties. These tests provide many segments of the industry with unbiased, independent data on the performance of varieties from several seed companies when tested side-by-side under typical production practices. Ten trials were planted in the cotton producing areas of the state, ranging from Wellton in Yuma county to Kansas Settlement in Cochise county. Seed companies entered a maximum of two varieties per location resulting in eight to thirteen commercially available varieties per test. The results show that many varieties performed well at several locations, indicating good adaptation to Arizona conditions.
    • Comparison of Obsolete and Modern Cotton Cultivars for Irrigated Production in Arizona

      Holifield, C. D.; Silvertooth, J. C.; Moser, H.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      A study was conducted at the University of Arizona Maricopa Agricultural Center (MAC) to compare growth and development characteristics and determine differences in fruiting pattern and retention among two obsolete (Deltapine 16 and Acala 442) and three modern (Deltapine Acala 90, Deltapine 5415, and NuCotn 33b) Upland (G. hirsutum L.) cotton cultivars grown in an irrigated production system in Arizona. Results indicated that the majority of yield was produced at fruiting branches 10 through 18 at position one. Lint yield results indicated no significant differences among all cultivars tested, except for Acala 442, which was significantly lower than all others. Obsolete cultivars produced significantly higher amounts of lint on vegetative branches than modern varieties. Deltapine 16, followed by NuCotn 33b, had the highest harvest index and was the most efficient cultivar grown with respect to dry matter partitioning.
    • Cotton Defoliation Evaluations, 1999

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      Two field experiments were conducted near Marana and Coolidge, AZ in 1999 to evaluate the effectiveness of a number of defoliation treatments on Upland (var. DP 33b and AP 6101) cotton. All treatments consisted of materials commercially available in Arizona. Results reinforce general recommendations regarding the use of low rates (relative to the label ranges) under warm weather conditions and increasing rates as temperatures cool. Defoliation treatments of Ginstar alone did a satisfactory job of defoliation and regrowth/topgrowth contol and were very similar to treatments including Prep or Integrate. Adding Prep or Integrate to Ginstar in this experiment did not improve defoliation or topgrowth control.
    • Cotton Fertility Study, Safford Agricultural Center, 1999

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      Three different nitrogen fertilizer regimes were practiced in this study along with an unfertilized check. The same amount of nitrogen fertilizer was sidedressed in the plots in one, two or three applications. No statistically significant differences were seen between lint yields in this study nor in the previous study, but the yield trends were very similar. Applying the fertilizer nitrogen in two equal portions at the onset of rapid vegetative growth and just before peak bloom appeared to produce the best lint yield.
    • Date of Planting by Long Staple and Short Staple Variety Trial, Stafford Agricultural Center, 1999

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      Four varieties each of Long Staple and Short Staple cotton were tested over five and four dates of planting, respectively, in this study. The first date of planting for the Long Staple cotton was the 18th of March and for Short Staple cotton the 1st of April. The latest planting was May 13th. Cultivars of differing maturities were tested for both long and short staple cotton to determine their optimal planting time. Many agronomic parameters were evaluated to determine the effect of different planting dates
    • Development of a Yield Projection Technique for Arizona Cotton

      Norton, E. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      A series of boll measurements were taken at numerous locations in cotton producing areas across Arizona in 1999 in an attempt to continue to develop a yield prediction model with a project that began in 1993. Results from 1995 showed the strongest relationship between final open boll counts and yield compared to a number of other measurements. Based on these results, data collection on boll counts began in 1996 and has continued in 1997, 1998, and 1999. Boll counts were taken as the number of harvestable bolls per meter. All boll count measurements were made within one week of harvest. Number of bolls per unit area were then correlated to lint yield and an estimate for the number of bolls per area needed to produce a bale of lint was calculated. Estimates using all four years of data combined indicate that approximately 38 bolls per meter are needed to produce one bale of lint per acre.
    • Economic Impacts of Bt Cotton Adoption: A National and Regional Assessment

      Frizvold, George; Tronstad, Russell; Mortensen, Jorgen; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      This study uses a quadratic programming model to estimate impacts of Bt cotton adoption on consumer benefits, cotton program outlays, and producer returns, by state and by grower adoption status. Three scenarios were considered simulating low, moderate, and high impacts of Bt cotton adoption. For the moderate impact scenario, U.S. benefits from Bt cotton adoption grew from $44 million in 1996 to $66 million in 1998. Annual U.S. consumer benefits ranged from $46– $55 million. Benefits to Bt adopters grew from $57 million in 1996 to $97 million in 1998. Losses to non-adopters fell from -$59 million in 1996 to -$8 million in 1998 as rising commodity program payments countered the impact of lower prices. In 1998, gains to Arizona Bt cotton adopters (net of adoption costs) were about $9 million, averaging over $15,000 per adopting farm.
    • Effect of Halosulfuron (Permit), CGA362622, Glyphosate (Roundup Ultra) and Pyrithiobac (Staple) on Purple Nutsedge Growing in a Fallow Field

      Veatch, Maren E.; McCloskey, William B.; Silvertooth, Jeff; Department of Plant Sciences, University of Arizona, Tucson, AZ (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      In the fall of 1999 an experiment was conducted to measure the effect of CGA- 362622, halosulfuron (Permit), glyphosate (Roundup Ultra) and Pyrithiobac (Staple) on purple nutsedge. Five rates of Permit (0.25, 0.375, 0.495, 0.75 and 1.0 oz a.i./A), three rates of CGA-362622 (3.035, 4.047, and 6.07 g a.i./A), and a single rate each of Roundup Ultra (0.75 lb a.e./A), Staple (1.5 oz a.i./A), Staple + Bueno 6 (2 lb a.i./A), and Staple + Fusilade (0.25 lb a.i./A) were applied either once or twice to field populations of purple nutsedge. Efficacy of each treatment was measured in three ways: phytotoxicity (stunting, chlorosis and/or necrosis) ratings were assigned to each plot (0 being no injury and 10 indicating death), the number of green leaves were counted on 3 large ($8 leaves) and 3 small (≤4 leaves) plants per plot at various times after treatment, and the amount of regrowth after the herbicide treatments was assessed. All of the herbicide treatments caused stunting, induced chlorosis and necrosis, and were fairly effective in controlling nutsedge plants treated at or before the 4-leaf growth stage. Only Permit and CGA-362622 effectively controlled plants treated at the 8-leaf growth stage after one application. The other four herbicides required two applications to obtain effective control. For the regrowth parameter parameters, Permit, CGA-362622 and Roundup Ultra effectively controlled regrowth, but the Staple, Staple + Bueno 6 and the Staple + Fusilade treatments did not control regrowth. Two applications of Permit at the .495 oz a.i./A or greater rates, Roundup Ultra (0.75 lb a.e./A) and 1 or 2 applications of the 6.070 g a.i./A rate of CGA-362622 controlled nutsedge with respect to all measured regrowth parameters and may be the best choices for controlling purple nutsedge.
    • Effects of Aqueous Sprays of Silverleaf Whitefly Honeydew Sugars on Cotton Lint Stickiness

      Henneberry, T. J.; Forlow Jech, L.; Hendrix, D. L.; Steele, T.; Silvertooth, Jeff; USDA-ARS, Western Cotton Research Laboratory (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      Sprays of commercially-procured sugars that are also found in silverleaf whitefly Bemisia argentifolii Bellows and Perring [= B. tabaci (Gennadius) Strain B] honeydew were applied to clean cotton lint to determine the relationship between the sugars and cotton lint stickiness. Increasing concentrations of the sugars resulted in increasing thermodetector counts.
    • Effects of High Frequency Irrigation on Irrigation Uniformity II

      Martin, E. C.; Wegge, R.; Sheedy, M.; Silvertooth, Jeff; University of Arizona, Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      Another year of data was collected to determine the effects of high frequency irrigation on irrigation uniformity in cotton production. A field located at the Marana Agricultural Center was split into two treatments. Treatment one was irrigated at approximately 35% depletion of available water in the plant rootzone. Treatment two was irrigated at approximately 65% depletion in the crop rootzone. Increased frequency of irrigation has shown improved yields in many cotton studies. However, these more frequent and lighter irrigation applications may cause problems with irrigation uniformity. Frequent rains during critical time periods made it difficult to ascertain the impact of the irrigation schedule on uniformity. However, the less frequent, heavier application rate did result in a more uniform irrigation.
    • Evaluation of a Calcium-Based Soil Conditioner in Irrigated Cotton

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      A two site evaluation of a calcium (Ca²⁺)-based soil conditioner was conducted during the 1999 cotton season. The two locations included one at the Maricopa Agricultural Center (MAC) in Maricopa, AZ and the other was on a growercooperator field in Tacna, AZ. Both studies involved the use of CN-9, a Ca – nitrate solution with 9% nitrogen and 11% Ca. At MAC theCN-9 solution was sprayed over the seedbed post planting but prior to the first water-up irrigation. At the Tacna site CN-9 was applied in a sidedress application at planting. Routine plant measurements were taken throughout the duration of both studies and lint yield estimates were made at each location at the end of the season. No significant differences due to the application of CN-9 were detected in any data collected.
    • Evaluation of a Feedback Approach to Nitrogen and Pix Applications, 1998 and 1999

      Norton, E. J.; Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      A single field experiment was conducted at Marana, AZ in 1988 and 1999 to evaluate a scheduled (based upon stage of growth) versus a feedback approach (based upon growth parameters and crop conditions) to nitrogen (N) and mepiquat chloride (PixTM) applications on Upland cotton (Gossypium hirsutum L.). The parameters used in the feedback applications for both N and Pix included fruit retention (FR) levels and height to node ratios (HNRs) with respect to established baselines for irrigated cotton grown in the desert Southwest. Treatments consisted of all combinations of feedback and scheduled applications of both N and Pix. In 1998, the highest lint yields occurred in the treatment consisting of Pix feedback and N feedback (treatment two) management. However, there were no significant differences (P≤0.05) among any of the treatments with respect to yield. In 1999, significant light yield increases (P<0.05) were found in the treatments consisting of Pix feedback and N feedback (treatment two), Pix scheduled and N scheduled (treatment three), and Pix scheduled and N scheduled (treatment five) management approaches.
    • Evaluation of an Arid Soil Conditioner in an Irrigated Cotton Production System

      Norton, E. R.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      A single field study was conducted on a sodium-affected soil at the University of Arizona’s Maricopa Agricultural Center (MAC) in 1999. Deltapine DP33B was dry planted and watered-up on 13 April 1999. Two treatments were evaluated; treatment 1 received no acid and treatment 2 received water-run acid applications. The acid used in this evaluation was sulfuric acid (H2SO4) and was applied at approximately 11 gallons acid/acre at each scheduled irrigation throughout the entire growing season. All other agronomic inputs and decisions were uniformly applied to both treatments. Lint yields were not significantly different.
    • Evaluation of Commerical Ultra Narrow Cotton Production in Arizona

      Clay, P. A.; Isom, L. D.; McCloskey, W. B.; Husman, S. H.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      Seven commercial ultra narrow row (UNR) cotton fields were monitored on a weekly basis in Maricopa County, AZ in 1999. Varieties of Delta Pine and Sure Grow were planted from April 15 to June 1 and reached cut-out after accumulating 1913 to 2327 heat units after planting. Average yield for UNR cotton was 2.1 bales per acre which was 0.4 bales per acre lower than the five year average for cotton planted on conventional row spacings. Fiber quality from gin records for 801 bales had average micronaire readings of 4.54 and grades of 11 and 21 for 74% of bales. Discounts for extraneous matter (bark, grass, and cracked seed) was 5.4% and average strength (34.8) and staple lengths (27.12) were in acceptable ranges. Total cash costs ranged from $450 to $705.
    • Fertility Management and Calibration Evaluations on Upland and Pima Cotton

      Thelander, A. S.; Silvertooth, J. C.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      Numerous field experiments were conducted during the 1997 through 1999 cotton seasons involving macro and micronutrient fertilization. The purpose of these experiments was to evaluate University of Arizona (UA) fertility guidelines with respect to soil test results and to possibly fine-tune or better calibrate these guidelines for common Arizona soils and cotton growing regimes. Field experiments studied the effects of a single nutrient or nutrient combinations on both Upland and Pima varieties. Results from these experiments, based on soil test information, quantitative plant measurements, and lint yield showed no significant difference due to treatments for all sites except for a phosphorus study conducted during the 1998 season in Graham County and a phosphorus study conducted during the 1999 season in Pinal County. All results reinforce current UA soil testing guidelines for cotton.
    • How to Obtain Cotton Advisories from the Internet

      Brown, P.; Russell, B.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      Weekly production advisories and weather updates are now available from the Internet. Nineteen location-specific advisories are developed each Monday morning and then transferred to the Main AZMET Internet Web Page located at URL address http://ag.arizona.edu/azmet. To retrieve advisories or updates from the Internet users must 1) log on to the Internet using the procedures required by your Internet service provider; 2) enter the URL for the Main AZMET Web Page; 3) move to the Cotton Advisory sub-page; and 4) select the advisory or update of interest. Advisories for the most recent week, this year to date, and all of 1999 are available at this Internet address.
    • Influence of Ironite and Phosphorus on Long and Short Cotton on the Safford Agricultural Center, 1999

      Clark, L. J.; Carpenter, E. W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      Ironite and phosphorus were applied to plots planted to long and short staple cotton to find their effect on crop development and lint yield. The soil analysis indicated sufficient iron and phosphorous in the soil for cotton production and that yield increases from additions of these elements were unlikely. No statistically significant increases in lint yield were seen with the addition of Ironite nor phosphorous fertilizer. However, an interesting yield trend with ironite was seen in long staple cotton.
    • Johnsongrass Control in Cotton with BAS 620

      Clay, P. A.; Isom, L. D.; Silvertooth, Jeff; University of Arizona Cooperative Extension (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      Johnsongrass control with BAS 620 was 60% and 67% for the 0.124 and 0.248 lb ai/A rates respectively, 14 d after initial application. Control was comparable to Select at the corresponding rates. Control 28 d after the second application of graminicides ranged from 60% to 88%. Both rates of BAS 620 and Select as well as Fusilade DX provided the most effective control. Seed cotton yields ranged from 1347 to 3134 lbs/A and all herbicide treatments yielded significantly greater than the nontreated check.
    • Lygus Control Decision Aids for Arizona Cotton

      Ellsworth, Peter C.; Silvertooth, Jeff; The University of Arizona, Department of Entomology & Maricopa Agricultural Center (College of Agriculture, University of Arizona (Tucson, AZ), 2000)
      Changes in insecticide use, available pest control technologies, and local crop ecology together with severely depressed cotton prices place a renewed premium on Lygus control decision aids for Arizona cotton. As part of an on-going program to develop research-based Lygus management recommendations, we investigated the impact of various timings of chemical controls on Lygus population dynamics, number of sprays, costs of control, and net revenue as well as cotton heights, trash, lint turnouts, and yields. Once there were at least 15 total Lygus per 100 sweeps, sprays were made according to the number of nymphs in the sample (0, 1, 4, 8 or 16 per 100 sweeps). Up to 7 sprays were required (15/0 regime) to meet the needs of the target threshold. Lygus adult densities were largely unresponsive to the treatment regimes or individual sprays made. Three generations of nymphs, however, were affected by the treatments with the ‘15/4’ regime harboring the fewest nymphs through July. This ‘moderate’ regime required 4 sprays and had the shortest plants, cleanest harvest, and highest lint turnouts. In addition, this regime out-yielded all other treatment regimes including the 6- (15/ 1) and 7- (15/0) spray regimes. Regression analyses of the data suggest that adult Lygus are less related to yield loss than nymphs and that large nymphs are best correlated with yield loss. Thus, spraying based on adults only would appear illadvised. Returns were highest ($747/A) for the 15/4 regime with over $100 more than the more protective regimes. Thus, there is no economic advantage in advancing chemical control when nymph levels are low. Maximum economic gain was achieved by waiting for the 4 nymphs per 100 level (with 15 total Lygus/100; 15/4) before spraying. However, waiting too long (beyond the 8 nymphs / 100 level; 15/8) resulted in significant reductions in yield and revenue. Our recommendations, therefore, are to apply insecticides against Lygus when there are at least 15 total Lygus, including at least 4 nymphs, per 100 sweeps. These recommendations are stable over a wide variety of economic conditions (market prices & insecticide costs). Continued work is necessary to verify these findings over a wider range of cotton developmental stages, varieties, and other environmental conditions.