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.

This experiment tested the effects of a cytokinin containing product (Dry Seed +) on CUF 101 alfalfa when applied with the seed at planting on October 24, 1996, at the rate of 1 /lb product to 100 lb of alfalfa seed. Data indicated a non - statistical yield response averaging 200 lbs an acrefrom treated fields the first cutting, valued at $11 /acre, but yields were identical the second harvest. Alfalfa quality means were very similar for both harvests. A positive net return of $9.76 /acre was noted by using Dry Seed +. More testing is suggested to confirm these findings.

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.

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.

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.

Soil Sunburst was applied at the rate of one quart per acre at two treatment levels (single vs. two applications, applied once per cutting) in irrigation water to a first year stand of CUF 101 alfalfa. Treatments were applied in the first irrigation after the previous cutting in May and June 1996. Treatments applied in May increased relative feed value by over 10% compared to the untreated check in the first cutting (June) after application. This increased alfalfa quality rating from fair to good which increased value of hay by approximately $14 /acre. Mean yields between the treatments and untreated plots were similar, although average yields in untreated plots were 50-90 lbs /acre greater than in treated plots. Yields and quality data were not able to be obtained the second harvest (July), not allowing differences, if any, between one and two applications to be determined immediately after the second application. Yields and hay quality values for treatments in the August harvest were almost identical, indicating that treatment effects noted from the May application (and possibly those of the June application) were short term effects, as they did not continue through the August cutting.

The plant growth regulator Soil Triggrr was applied in basin flood irrigation water to the first (following previous cutting) and last irrigations of a third year stand of CUF 101 alfalfa before a late June 1995 harvest. Effect of product on yield may have been limited by pH as irrigation water pH was approximately 7.9. An increase in yield was noted with product usage, with a greater yield increase noted when applied earlier in crop cycle (first irrigation = 136 lbs hay /acre) rather than later in crop development cycle (last irrigation = 34 lbs hay /acre) when compared with the untreated check Yield from the next (July) harvest was not obtained Yield differences were not statistically different or economic for a single harvest in this experiment. Alfalfa quality was not obtained.

New alfalfa varieties are constantly being introduced into the marketplace. The number of varieties available for low-elevation desert areas in Arizona in the non-dormant and very non-dormant class is close to 50. New varieties are introduced each year and unbiased yield comparisons are helpful to the grower to base the decision of whether or not to sow a new variety. The study reported here is part of the on-going effort to evaluate alfalfa variety performance in Arizona. A summary of small grain variety trials conducted by the University of Arizona can be found online at http://ag.arizona.edu/pubs/crops/az1267.pdf.

Three insecticides and one herbicide (Prism®) were evaluated efficacy against summer alfalfa insects using small plots. Usage of the insecticide Steward® resulted in excellent control of alfalfa caterpillars and beet armyworms, as well as excellent initial control of Empoasca leafhoppers. Usage of Steward® also reduced nymphal lygus bugs, but also resulted in lowest numbers of bigeyed bugs. Application of the insecticide Baythroid® XL was noted to result in excellent control of Empoasca leafhoppers throughout the study, excellent control of palestriped flea beetles early in the study, but also reduced populations of damsel bugs early in the study. Reduction of threecornered alfalfa hoppers was also noted, as was excellent control of alfalfa caterpillars at one and seven days post treatment with this chemistry, although this was not noted at four days after treatment. Data indicate the herbicide treatment (Prism® + Hasten®) significantly reduced damsel bug populations and large lygus bug nymphs for one day post treatment, and resulted in a slight numerical decrease in beet armyworms and palestriped flea beetles. Clover leafhopper numbers where higher at seven days post treatment in alfalfa receiving this treatment than the untreated check. Application of Trilogy®, expected to be a slow acting treatment, did result in some slight initial reductions (25%) of palestriped flea beetles, threecornered alfalfa hoppers and beet armyworms, but these red uctions were not apparent at four days post treatment. Usage of Trilogy® resulted in highest Empoasca leafhopper populations at seven days post treatment, although the reason for this observation is unknown.

Alfalfa has the highest water requirement of any crop grown in Arizona, and any strategies that conserve water growing this crop could have a large impact on water availability in the state. The purpose of this study is to determine yield and profitability of sub-optimal irrigation strategies in alfalfa. An irrigation study was conducted at the University of Arizona Maricopa Agricultural Center on a sandy clay loam soil. The following irrigation treatments are included in this study: 1) One irrigation per cutting, 2) Two irrigations per cutting, 3) Summer (August) irrigation termination, 4) Winter (December, January, February) irrigation termination, and 5) Summer and Winter irrigation termination. The Winter irrigation termination treatments were initiated in December 2009 and data is not available yet for these treatments. The amount of water applied from January through November 2009 was 69.7 inches (one irrigation per cut), 80.5 inches (two irrigations per cut), and 78.6 (Summer irrigation termination). The annual hay yields were 12.5 tons/acre (one irrigation per cut), 13.7 tons/acre (two irrigations per cut), and 12.9 tons/acre (Summer irrigation termination). Sub-optimal irrigation increased the forage quality by decreasing fiber (ADF and NDF) and increasing protein content. Sub-optimal irrigation did not reduce stand density. The water use efficiency of applied water (plus rainfall) was not affected by irrigation treatment.