A test was conducted on established alfalfa to evaluate the efficacy of 10 herbicide treatments for the control of shepardspurse (Capsella bursa). Control ranged from 13 to 99 percent.

A test was conducted to compare EPTC applied preplant to alfalfa as a 10% granule and as a emulsifiable concentrate metered into the irrigation water. Observations and measurements on weed control and phytotoxicity were recorded EPTC appeared to be more active in controlling weeds and injuring seedling alfalfa when applied to 3.0 lb./acre as a granule rather than the same rate applied as a water run.

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.

No description available.

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.

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 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.

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.

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.

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.