• Efficacy of Norflurazon for Nutsedge Control in Parker Valley Alfalfa

      Knowles, Tim C.; McCloskey, Bill; McGuire, Jerry; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Summer weeds such as nutsedge are of economic concern to alfalfa growers in western Arizona. A two year replicated evaluation of the effectiveness of granular norflurazon herbicide for purple nutsedge control was conducted on an established alfalfa field in La Paz County. Zorial Rapid 80 WP and Evital 5G herbicides were tested for their effectiveness at controlling purple nutsedge when applied following hay harvest but prior to irrigation in early spring and late summer. Zorial 80 WP was applied at 2.0 lb a. i. /acre. Evital 5G was applied in spring 1996 at application rates of 1.0, 1.5, 2.0, and 3.0 lb a. i. /acre. Split applications were made the following summer to four plots for a total of 2.0, 3.0, and 4.0 lb a. i. /acre/year. In 1996, purple nutsedge control resulting from a single application of Evital 5G at 2.0 lb a. i. /acre was 41, 82, and 35% at 35, 63, and 99 DAT, respectively. However, Zorial 80 WP applied at 2.0 lb a. i. /acre provided poor purple nutsedge control due to poor soil incorporation since the liquid was unable to penetrate the dense nutsedge foliage. The treatments were reapplied in spring and summer of 1997.
    • Bermudagrass Control in Alfalfa Using Clethodim (Prism) and Two Formulations of Sethoxydim (Past Plus, Ultima)

      Husman, Stephen H.; McCloskey, William B.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Two successive applications of Poast Plus (60 oz. product /A, 0.47 lb. sethoxydim /A), Ultima 160 (46 oz. product /A, 0.47 lb. sethoxydim /A), and Prism (34 oz. /A, 0.25 lb clethodim/A) were made on May 31 and June 27, 1996 to control bermudagrass (Cynodon dactylon) in a commercial alfalfa field. A crop oil concentrate was added to all herbicide solutions. Applications were made two days after the irrigations that followed removal of the cuttings. The bermudagrass density was high with extensive stolon development; the grass formed almost a complete mat in most of the plots. Percent control was visually estimated on June 27 (prior to second application) and on July 25, 28 days following the second application and after cutting of the alfalfa. Percent control was 84.5, 71.2, and 65% for Poast Plus, Ultima, and Prism, respectively, after one application. Percent control was 87.5, 72.5, and 90.5% for Poast Plus, Ultima, and Prism, respectively, after two applications. A single application of Poast Plus resulted in good bermudagrass control but single applications of Ultima or Prism resulted in marginal control. The second application of Prism significantly improved bermudagrass control but the second application of Poast Plus or Ultima did not improve control. The Poast Plus formulation of sethoxydim appeared to be superior to the Ultima 160 formulation of sethoxydim.
    • 1995-1997 Alfalfa Yields of Five Varieties Planted October 1994 on the Colorado River Indian Tribes Reservation

      Rethwisch, Michael D.; Baldwin, Bill; Baldwin, John; Leivas, Danny; Kruse, Michael; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      This report covers the first 2.5 years of production of five alfalfa varieties (CUF 101, SW 14, SW8210, Pioneer 5888, and a grower selection originating from CUF 101 and noted as Baldwin Select) that were planted in October, 1994, into large plots (0.75 acres) to obtain actual field harvest data. Data are reported from 22 harvests thus far in the study, including five from 1997. Varietal hay yields were very similar in 1995 until mid summer, when area soil temperatures reached above 100°F at the four inch depth for a period of about 6 weeks. During the summer months of 195 -1996 Baldwin Select had significantly higher yields than other varieties tested. Statistical differences in accumulated hay yields were noted beginning in August 1995 and have continued. during 1996. Baldwin Select has the highest yielding variety each year thus far, producing 8.8% more than CUF 101, worth $233 /acre. Alfalfa varieties have been very similar in relative feed value when tested. Yellowing from Empoasca spp. leafhoppers was greatest during the 1995 -1996 winter on varieties with fall dormancy ratings of 9 or greater. Weed infestations during late summer 1996 appear to be inversely correlated with fall dormancy, for which Baldwin Select significantly higher than CUF 101.
    • Alfalfa Hay Yields for Two Years of Eight Varieties Planted in February 1995 on the Colorado River Indian Tribes Reservation

      Rethwisch, Michael D.; Sokiestewa, Hipkoe; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Eight alfalfa varieties were evaluated for forage production during 1995 and 1996 following a Feb. 1995 planting. DK 189 yielded the most tonnage in both years of production (104.4% of CUF 101) and Mecca II the least amount (95.9% of CUF 101). Although five varieties had higher yields than CUF 101 during the second year of production, only DK 189 and WL 525 HQ averaged higher yields than CUF 101 for the two year duration of this study.
    • Alfalfa Variety Trial in Cochise County, Arizona, 1996

      Clark, L. J.; Carpenter, E. W.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Fourteen alfalfa varieties with fall dormancy ratings from 6 to 9 were tested in replicated small plot trials on the Kibler farm in Stewart District northwest of Willcox. The leading variety after two year of testing was DeKalb 189 with a dry matter yield of 8 tons per acre. Heat units with temperature thresholds of 77 °F and 40 °F are given for each cutting .
    • Alfalfa Variety Trial in Graham County, Arizona, 1996

      Clark, L. J.; Carpenter, E. W.; Cluff, R. E.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      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 first year of a new study and there were some difficulties caused by irrigation management on the heavy soil. Pioneer 5888 was the highest yielding variety with a yield just over 9 tons per acre in 6 cuttings. Heat units with thresholds of 77 F and 40° F are included for each cutting in the study.
    • Alfalfa Variety Performance at Maricopa, 1995-97

      Ottman, M. J.; Smith, S. E.; Fendenheim, D.; Parsons, D. K.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
    • Comparisons of Lorsban 4E and Spinosad 4SC for Control of Summer Insects in Alfalfa

      Rethwisch, Michael D.; Kruse, Elizabeth; Kruse, Michael D.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Anew chemistry (Spinosad 4SC) was tested for control of beet armyworm and other summers insects in alfalfa. This product did not control beet armyworms as well as the top of label rate of Lorsban 4E, and at one day post treatment had more beet armyworms than the lowest rate of Lorsban tested At three days post treatment both rates of Spinosad 4SC had fewer beet armyworms than the lowest rate of Lorsban tested. Few differences were noted between Spinosad 4SC for beet armyworm control, although fewer alfalfa caterpillars were noted with usage of the higher Spinosad rate, although significantly more beneficial insects were noted at three days post treatment with the lower rate of Spinosad. Lorsban chemistries significantly lowered yellows and hopperburn damage ratings compared with other treatments and a difference was noted between the two Spinosad rates although Empoasca sp. leafhopper numbers were similar.
    • Influence of Folocron Nitrogen Fertilizer Applied in Summer on Alfalfa Yield During Summer Slump

      Knowles, Tim C.; Ottman, Michael J.; Wakimoto, Victor; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Established alfalfa reportedly does not benefit rom applications of N fertilizer since it is a leguminous crop that is capable of fixing its own N from atmospheric N. Some growers feel that nitrogen (N) fixing nodules found on the roots of the alfalfa plant are ineffective during Arizona's hot summers . Thus, N fertilizer is sometimes applied in early summer to established alfalfa to enhance growth and possibly delay or lessen the severity of summer slump to increase alfalfa tonnage. A field experiment was conducted to determine the effect of inorganic and controlled release N fertilizer applied in summer on alfalfa hay yield at the first cutting during summer slump. Three treatments consisted of an unfertilized check plot, broadcast 18-46-0 applied at 27 lbs. N /acre, and Folocron water run at a rate of 30 lbs. N /acre in August to three year old 'CUF 101' alfalfa grown on a silt loam soil. Maximum alfalfa hay yield at the September cutting (0.91 ton/acre) was obtained without N fertilizer application.
    • Overview of Alfalfa Production and Market Trends in La Paz County

      Knowles, Tim C.; Winans, S. Sherwood; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Alfalfa producers in the Colorado River region of La Paz County have experienced some shifting trends in markets and production over the last 15 years. Acreage has increased steadily from a low of 25,000 acres in the early 1980's to a high of nearly 45,000 acres in 1997. Average annual alfalfa hay yields in La Paz County have maintained a fairly flat trend ranging from 7.5 to 8.5 tons per acre during this time. Alfalfa hay prices were severely depressed during the summer of 1986, from summer of 1991 through winter of 1992, and during the summer of 1995. In contrast, La Paz County alfalfa hay producers experienced the strongest markets during the winters of 1984, 1990, and 1995. More recently, since the winter of 1996, producers have experienced the strongest alfalfa hay market in the history of La Paz County with on farm prices reaching an all time high of $136 per ton.