The stem nematode Ditylenchus dipsaci attacks non-dormant Arizona alfalfa in the desert valleys; damage occurs during the cooler months of fall and spring. Efforts to introduce and retain resistant alfalfa has had limited success. From October until temperatures decrease below 50 F., the nematode reproduces and feeds. In warmer years, damage may be sustained from October until spring temperatures exceed 85 F. Chemical control may be warranted during these periods of feeding activity. Field trials were established to determine the efficacy of pesticides registered for use in alfalfa. Temil; Vydate, Furdan, Disyston, Thimet and Dasanit applied either in fall or spring were effective in controlling populations when first detected following dormancy. The best control is obtained when pesticides are applied immediately after harvest and prior to irrigation. Yield increases up to 15-25% were obtained with decreased yields in non -treated controls of 40-80%. Stand decline was reduced as much as 50% when treatments were correctly applied.

Continued irrigation with saline water on Arizona's already salty farm lands will increase the need for crops that are able to maintain yields under stress. We investigated responses of gemùnation salt- tolerant alfalfa (Medicago sativa L.) to salt and temperature stress interactions in comparison to Mesa - Sirsa. Significant interactions were found for the populations, salts and temperatures and their effects on percent germination. The germination salt - tolerant cycles proved to be more cold and heat tolerant under salt stress then Mesa - Sirsa.

No description available.

Four major non - dormant alfalfa varieties were tested over 1986 and 1987. No differences in yield or quality of the varieties were determined.

Ten alfalfa varieties ranging from very non - dormant to moderately dominant were compared over two seasons. Significant differences were observed between yields of top varieties from 1986 to 1987. Baron, the highest yielding variety for 1986 ranked 3rd in 1987, with Valiant moving from seventh to first in 1987. Overall yields increased from seven tons in 1986 to almost eleven tons per acre in 1987. The previous county average was 5.5 ton per acre.

No description available.

Increasing crop salt tolerance can mean higher yields on irrigated farmland and salt -affected soils. Three cycles of selection were made for growth of alfalfa seedlings under 7500 ppm NaCl. Comparison of parent and selected populations was made for yield and germination under saline conditions. Yield of the last cycle was significantly improved. Germination of the last two cycles was higher than that of the parent and cycle 1.

For the past three years, ten alfalfa varieties have been grown and yields recorded. Yields in excess of 9 tons per acre were harvested in 1988 on 7 of the 10 varieties. Baron, a moderately nondormant variety, was the highest yielding variety for the three years, with an average yield of 8.9 tons per acre.

A new alfalfa variety trial was planted in the fall of 1987to replace the previous four-year trial. The top varieties from the previous trial were placed in the new trial, along with new, promising varieties. A single year's data is insufficient to judge the performance of a variety during its useful years of production. The data simply indicate performance in their first year. Pioneer 5929, the variety that had the best overall yield in the previous trial (1), performed well in this trial as well. However, Mecca, a new variety from Plant Genetics, Inc., had the highest yield.

Replicated herbicide experiments were carried out on alfalfa fields in Graham and Greenlee counties in the winter of 1989. Five herbicides were tested; tanzy mustard and (oxtail barley were the mails target weed species. Velpar L applied on at a rate of 4 pints per acre in 20 gallons of water provided the best control with 99% control of the broad -leafed weeds and 86% of the grassy weeds just prior to the first cutting. Better control of foxtail barley probably would have been achieved by several of the herbicides if they had been applied earlier, before the weeds germinated and /or if the materials had been incorporated by an adequate irrigation or rainfall.