This report summarizes data from several studies conducted along the Colorado River in recent years for control of Empoasca sp. leafhoppers, threecornered alfalfa hoppers, and western big-eyed bugs. Data were rearranged and presented in an easy to understand format for insect pests control utilizing a time sequence corresponding to sampling dates after application, a method not always readily 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 fifth and final year of the study. Prestige was the highest yielding variety in 2000, but that still left it in sixth place behind Cuf 101 and WL 91-224F, which averaged 8.25 tons per acre over the five years of the study. Heat units with thresholds of 77° F and 41° F are included for each cutting in the study and percent of final stand count are recorded.

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 second year of the study. Coronado was the highest yielding variety in 2000 with Mecca III following closely behind. Both varieties produced a yield over 9 tons per acre and averaged 9.3 tons per acre over the 2-year period.

Six treatments containing carbohydrates and/or fertilizer were applied to alfalfa shortly after cutting in July 2002 to help ascertain if foliar applied carbohydrates would be helpful in overcoming summer slump of alfalfa hay production in the desert southwest. No significant differences were noted for any treatment for yield or quality when compared with the untreated check, although a trend for increased quality from treatments was noted. Highest yielding treatment was DC34, which increased tonnage by less than 0.1 tons/acre compared with the untreated check. DC34 was also among the highest in alfalfa quality. Alfalfa treated with Amaze® had the highest quality, but no affect on yield. As applications were made when little green foliage was available, most of the applied treatments did not actually contact green tissue but brown/dessicated alfalfa tissue or bare soil. Applying treatments during the regrowth cycle when more foliage is available may result in improved results as suggested by the trends noted from this experiment's treatments, however further testing will be necessary to verify such results.

Three plant growth regulators (two for growth enhancement, one for growth inhibition) were applied to several consecutive cuttings of alfalfa during the period of May-August in the Blythe, CA, area. All treatments resulted in reduced tonnage compared to the untreated check, although application of prohexadione calcium (active ingredient in the growth inhibition plant growth regulator) did result in increase in alfalfa quality when applied in May. Subsequent applications during the summer of this material did not result in a quality class increase for alfalfa hay production. Treatments of growth enhancement chemistries did result in less tonnage, however, data indicate that this reduction may be due to nutritional needs of alfalfa not being supplied during periods of increased growth. Supplemental nutrition along with the growth enhancement chemistries has not been tested to determine resulting alfalfa yields.

"A number of products with miticidal activity were applied both in the spring and summer of 2002 to alfalfa in the Blythe, CA, area to evaluate their efficacy for twospotted spider mite (Tetranychus urticae) control. These two application periods differed in regards to presence of western flower thrips (Frankliniella occidentalis), a predator of spider mites. Western flower thrips populations were high in the spring but essentially absent during the period following the summer application, providing contrasting data for effects of western flower thrips interactions with many miticides for spider mite control. Miticides tested included those currently utilized for mite control in alfalfa hay production as well as a number of new and/or potential products for alfalfa hay. In the spring testing, most treatments had more spider mites than the untreated check at three days post treatment when western flower thrips were present and actively feeding on spider mites. Two fertilizer treatments that contained high amounts of sulfur also had more spider mites than the untreated check at three days post treatment, thought due to repellency of adult western flower thrips. Many of the treatments that had more spider mites than the check following the spring application are known to have thrips activity (Zephyr, Trilogy, Dimethoate, Lorsban, etc.). Fewer motile (adults and immatures, not eggs) spider mites than in the check were noted only from the Capture + Dimethoate 400, Capture, and the combination of the two Gowan numbered products (1528, 1549) at three days after treatment. Products that provided excellent (90%+) control throughout the duration of the summer part of the experiment included two numbered compounds from Gowan (1528 and 1549), Capture + Dimethoate 400, Danitol, Zephyr + Trilogy, and a numbered compound from Valent USA (V-1283). The wide disparity in the two data sets indicate that western flower thrips presence/absence should be considered as part of the decision making process for spider mite control. "

An experiment was initiated utilizing a swather based sprayer to determine if miticides applied at cutting would be an effective control method of spider mites in low desert alfalfa hay. Two treatments (Trilogy, Trilogy + Kinetic) were applied the morning of May 23, 2003, to alfalfa with very high numbers of spider mites. Treatments had five replications, with plots sampled on June 2, 9 and 18. Data indicated a severe reduction in spider mite numbers as of June 2 in all treatments (including untreated) thought due to high temperatures experienced shortly after cutting that exceeded lethal thresholds for spider mite survival. Differences in treatments for spider mites or western flower thrips were not noted until June 18, when significantly fewer spider mites were noted in Trilogy treated plots than untreated check plots. Trilogy + Kinetic treatments resulted in numerically fewer spider mites than the untreated check on this sample date, but numerically more than Trilogy treatment.

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 fourth year of the study. Coronado was the highest yielding variety in 2002 with Mecca III and ZX9393 following closely behind. All three varieties produced a yield over 6 tons per acre and averaged over 8 tons per acre over the 4-year period.

No description available.

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 about 46. 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. The data contained in this report are also available at http://www.ag.arizona.edu/~azalfalf/yield/2000/. 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.