• Alfalfa Response to Forms of Phosphorus Fertilizer

      Ottman, Michael J.; Thompson, Thomas L.; Rogers, M. T.; White, Scott A.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      Many agricultural workers feel that 10-34-0 is a superior fertilizer for alfalfa since it is thought to move deeper in the soil with irrigation, be more available to the plant, and result in higher yields at equivalent rates compared to 11-52- 0. We found in our study with 24 cuttings over 3 years that alfalfa yields were similar if fertilized with 10-34-0 or 11-52-0 at equivalent rates. Total plant P was not affected by P fertilizer form or method of application. Broadcast 11- 52-0 resulted in higher soil P levels than water-run 10-34-0 and moved deeper in the soil profile. Broadcast 11-52-0 and water-run 10-34-0 appear to be equally effective P fertilizers for alfalfa in the irrigated southwest.
    • Alfalfa Tolerance to Norflurazon (Zorial 5G) on Coarse Textured Soils in Central Arizona

      McCloskey, William B.; Clay, Patricia A.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      The tolerance of seedling alfalfa to norflurazon applied at various times after planting was evaluated at the University of Arizona Maricopa Agricultural Center (MAC) and in Glendale, AZ during 1998 and 1999. At each application date, rates of 0, 1, 1.5, 2, 3, or 4 lbs a.i./A of norflurazon formulated as a 5% sand granule (Zorial 5G) were applied using a ground driven Valmar granule applicator. Zorial 5G at rates ranging from 1.5 to 4.0 lbs a.i./acre applied as early as 25 days after planting (DAP) had no effect on alfalfa seedling emergence and stand establishment at (MAC). Significant alfalfa height reductions were observed as Zorial 5G rate was increased when Zorial was applied at 25 and 62 DAP (MAC) and 64 DAP (Glendale). Alfalfa fresh weight yield for the MAC location was reduced at the second cutting after application as Zorial 5G rate increased for the at planting and 25 DAP treatments. Alfalfa yields approximately one year after planting were not affected by applications of Zorial 5G at 25 DAP or later. Results suggest that Zorial applications at rates of 1 to 2 lbs a.i./A applied at the 3 to 4 trifoliate leaf stage (approximately 2 months after planting) have little effect on yield at first and second cuttings of alfalfa.
    • Alfalfa Variety Trial on Heavy Soil in Graham County Arizona, 1999

      Clark, Lee J.; Carpenter, E. W.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      Twenty four alfalfa varieties with fall dormancy ratings of 8 or 9 were tested in a replicated small plot trial on a heavy clay loam soil on the Safford Agricultural Center. This was the fourth year of the study. WL 91-224F was the highest yielding variety in 1999, but that still left it in second place behind Cuf 101 for the four year average. WL 91-224F yield was 8.35 tons per acre which is very close to its four year average of 8.32 tons per acre. CUF 101 only had the heaviest yield in one out of the past four years, but its high 1998 yield gave it the highest average yield over the four years of the study, at 8.37 tons per acre per year. Heat units with thresholds of 77o F and 41o F are included for each cutting in the study.
    • Alfalfa Yield Response to Cutting Height and Cutting at Dawn and Dusk

      Ottman, Michael J.; Rogers, M. T.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      Alfalfa yield and quality can be affected by the height and timing of cutting. This research was conducted to determine if 1) raising cutting height from 2 to 4 inches could increase stem density particularly during the summer months, and if 2) alfalfa cut at dusk and the following dawn differ in dry matter yield. Alfalfa was harvested from small plots eight times during the year in an experiment conducted at the Maricopa Agricultural Center in 1999 on a third year stand. The 4 inch cutting height resulted in consistently lower yields compared to the 2 inch cutting height even during the summer despite having slightly higher stem density. The 2 inch cutting height produced 12.5 tons/acre over the year compared to 9.9 tons/acre for the 4 inch cutting height. Forage yield was 3.7% higher for alfalfa cut at dusk compared to the following dawn. Alfalfa cut at dusk and weighed the following dawn lost a similar amount of dry weight overnight compared to alfalfa left standing. Any yield advantage of cutting at dusk can only be realized by greenchopping and immediately feeding the forage.
    • Comparisions of Differing Rates of Baythroid 2® and WarriorT® Insecticides for Insect Control in Fall Alfalfa

      Rethwisch, Michael D.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      Various rates of two insecticides were tested for efficacy on threecornered alfalfa hopper and Empoasca sp. leafhoppers. Data were also collected for efficacy of insecticides on beneficial insects present. Hay quality samples were taken after baling. Both insecticides provided excellent control of threecornered alfalfa hopper, and Baythroid also controlled Empoasca sp.leafhoppers. Quality of hay was increased where threecornered alfalfa hoppers were controlled, although this control was for only eight days prior to cutting. A decrease in digestible hay protein was noted with increasing numbers of Empoasca sp. leafhoppers.
    • Effects of High Electroconductivity Field Conditions on Production of Six Alfalfa Varieties on the Colorado River Indian Tribes Reservation

      Rethwisch, Michael D.; Kruse, Michael D.; Leivas, Roy; Watson, Jack; Sheedy, Michael; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      Five alfalfa varieties were planted and grown under grower conditions on a field section that had high conductivity, while two varieties were planted and grown on a section of the same field much less affected. CUF 101, the variety grown in both areas, was the highest yielding variety in both area. Reduction in CUF 101 hay yield due to high conductivity was approximately one ton/acre in the first year of production, with a large amount of this noted in the first cutting. Yield reductions of CUF 101 due to field area and associated electroconductivity were greater the second year, with an average of 0.29 tons/acre/cutting. Total yield difference for CUF 101 was 1.72 tons/acre for the eight harvests for which data were available. Yield differences between the areas was greatest in the early spring and late fall of the first harvest year, with differences not noted in the June cutting; in year two yield differences were approximately 37% for each cutting. Salado was the second highest yielding variety in the high electroconductivity area in 1998, and equaled CUF 101 in yield from this area in 1999. Sal-T-96 and Leivas Best yielded less than 90% of CUF 101. Sal-T-96 also had the greatest number of weeds, due in part to very slow germination and fewer plants per acre compared with other varieties.
    • Evaluation of Raptor 1AS and Other Herbicides for Sowthistle, Canarygrass, and Wild Oat Control in Alfalfa

      Rethwisch, Michael D.; Nelson John E.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      Two rates of Raptor herbicide were evaluated for late winter weed control in alfalfa in combination with various types of surfactancts, the insecticide Furadan, and other alfalfa herbicides with known limited control spectrums. Herbicides that were combined with Raptor were also evaluated separately, as was Pursuit. Effects of treatments on wild oats, littleseed canarygrass and annual sowthistle were obtained. Treatments containing the active ingredient clethodim (Select/Prism) reduced canarygrass height and reproduction, while Raptor treatments increased numbers of inflorescences. No treatment provided effective control of sowthistle although some activity was noted from the Raptor treatments when numbers of reproductive structures and height were examined. Surfactants/ adjuvants greatly increased Raptor activity. Wild oat control was noted in treatments containing clethodim and several Raptor treatments when utilizing a surfactant/adjuvant.
    • New Alfalfa Variety Trial in Graham County, Arizona, 1999

      Clark, Lee J.; Carpenter, E. W.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      Twenty six alfalfa varieties with fall dormancy ratings of 8 or 9 were tested in a replicated small plot trial on a sandy clay loam soil on the Safford Agricultural Center. This was the first year of the study. Mecca III was the highest yielding variety in 1999 with Coronado following closely behind. Both varieties produced a yield close to 9.5 tons per acre.
    • Response of Alfalfa Treatedwith Halosulfuron during the Summer of 1999

      McCloskey, William B.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      The response of alfalfa regrowth, yield and plant populations to halosulfuron applied following cuttings and irrigations in the summer and fall of 1999 was studied in an experiment conducted at the University of Arizona Maricopa Agricultural Center. A single application of halosulfuron applied when there was little alfalfa foliage slightly reduced plant heights for several cutting cycles with increasing rate decreasing plant height. The cumulative forage fresh weight yields for the October 4th, November 15th, and February 22nd harvests for treatments receiving no halosulfuron or 0.032, 0.047, or 0.063 lb a.i./A were (means ± std. dev.): 15.94 ± 0.91, 14.99 ± 0.66, 14.80 ± 1.74, and 14.46 ± 0.97 tons/A, respectively. The trend of decreasing cumulative forage fresh weight with increasing halosulfuron rate was significant (Adj. R2 = 0.178, P = 0.015) indicating that for the three harvests after August 25th, halosulfuron had a small but negative effect on forage fresh weight. The harvest on April 5, 2000, the fourth harvest following the halosulfuron applications on August 25, 1999, indicated that there was no longer any residual effect of halosulfuron on alfalfa growth. Plant populations measured on April 10, 2000 were not affected by either one or two halosulfuron applications in this experiment. A set of sequential halosulfuron treatments applied when there was substantial alfalfa foliage (about 80% of the ground surface covered) severely suppressed alfalfa regrowth. Little regrowth occurred in these plots in October or November after the sequential applications compared to the untreated control or to the plots that received only the initial application of halosulfuron. The change in mean percent yield loss with successive harvests on November 15th, February 22nd and April 5th of 85, 40 and 14% indicated that the alfalfa plants were recovering from the halosulfuron applications. The cumulative forage fresh weight yields for treatments receiving sequential halosulfuron treatments (0.032+0.032, 0.047+0.047, or 0.063+0.063 lb a.i./A) were (means ± std. dev.): 11.67 ± 1.46, 10.85 ± 1.06, and 10.44 ± 0.98 tons/A, respectively, and were much less than the cumulative yield of 18.97 ± 1.17 tons/A from the untreated plots. The data suggest that the critical factor in determining the degree of alfalfa injury caused by halosulfuron is the amount of foliage present at the time of application.
    • Two Year Evaluation of Nine Alfalfa Varieties Grown Under Grower Conditions on the Colorado River Indian Tribes Reservation

      Rethwisch, Michael D.; Torres, Migues; Kruse, Michael; Torres, Javier; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 2000-10)
      Nine alfalfa varieties, most not previously tested under field conditions in Arizona, were planted October 29, 1997, using the same setting on a Great Plains Solid Stand 13 End Wheel drill. Varieties differed in lbs. of seed/acre planted, ranging from 28.0 for CUF 101 to 21.3 for Alto. Seven cuttings were obtained in 1998, a year characterized by much cooler than normal temperatures during April through early July. The variety Alto yielded significantly more hay than CUF 101 in the first cutting and had the highest total yield (10.61 tons hay/acre) in 1998, 4.9% greater than the area standard, CUF 101. Varieties with fall dormancy class ratings of 8 (Alto, WL 525 HQ, and Baralfa 85) had the highest yields during 1998, yielding at least 103% of CUF 101. During 1999, the top yielding varieties were Baralfa 92, Beacon, and Baralfa 85, which all yielded at least 105% of CUF 101. These varieties in addition to Alto yielded 103+% of CUF 101 through the first two years of production.