• Efficacy of Imazameth (Cadre) for Nutsedge Control in Parker Valley Alfalfa

      Knowles, Tim C.; McGuire, Jerry; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Summer weeds including purple nutsedge are of economic concern to alfalfa growers in western Arizona. Application rates of Cadre 2 ASU, a new sulfonylurea herbicide chemistry currently registered for experimental use in peanuts, for purple nutsedge control in a roadway bordering established alfalfa were examined in a two year duration, replicated field study. Fair to good (35- 65%) purple nutsedge control was obtained when Cadre was applied at the 3 oz/acre rate to a severe initial nutsedge infestation (80- 100%). Control was most effective when Cadre was applied in late summer compared to early spring, and repeat split applications were necessary under the high weed pressure observed in this study.
    • 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.
    • Feed Quality of Common Summer Grass and Broadleaf Weeds in Alfalfa Hay

      Knowles, Tim C.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Late summer grassy weed control is a questionable practice since it reduces alfalfa hay tonnage during summer slump, and the reduction in hay feed quality caused by these weeds in horse hay is questionable. A field experiment was conducted at the September alfalfa cutting to examine the feed quality of grassy and broadleaf weeds found in western Arizona hay fields at this time which corresponds with annual summer slump. These weeds included bermudagrass, junglerice (watergrass), Mexican sprangletop, Johnsongrass, purple nutsedge, and common purslane. Since hay cut during this period is used primarily for dry dairy cow and horse hay this study examined the suitability of alfalfa hay infested with these summer weeds as a feed for these animals. Based on this study, horse owners could benefit financially if they waited until late summer when hay prices slump, and purchase off-grade alfalfa hay containing less than one half grassy summer weeds for an economical, nutritious feed source.
    • Hay Yield and Quality of Sudangrass and Sorghum-Sudangrass Hybrid Varieties Grown for Export from Western Arizona

      Knowles, Tim C.; Ottman, Michael J.; Lloyd, Jim; Quist, Aron; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Two common sudangrass varieties (Piper and Sweet Sudan), four sudangrass hybrids (NK Trudan 8, Cargill HS 35, NC+ 200, and Germaine 's G 555), and three sorghum - sudangrass hybrids (DK SX 17, TE Haygrazer II, and Pioneer 877F) were evaluated for hay yield and quality at four cuttings in large field plots located at Quail Mesa Farms in southwest La Paz County. Results from four hay cuttings at one location are presented showing that of the nine sudangrass varieties examined in this study, Piper, NC+ 200, and Germaine 's G 555 sudangrass varieties had superior hay tonnage and quality.
    • 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.