DESICCATION OF ALFALFA FOR SEED PRODUCTION WITH DIQUAT AND GLUFOSINATE

Recommendations for desiccation of alfalfa do not clearly define the s tage at which desiccants should be applied. To obtain this information , diquat and glufosinate were applied to alfalfa (Medicago sativa L.) from 1991 to 1994 at various stages of maturity to determine the effec t of desiccant and stage of maturity at desiccation on seed yield, 100 0-seed weight and seed germinability. Alfalfa seed yields, 1000-seed w eights, percent germination and percent viable seed were similar after desiccation with diquat and glufosinate. Desiccation when 60-75% of t he alfalfa seed pods were brown permitted maximum seed yields. Percent germination increased slightly in seeds that were exposed to weatheri ng under normal conditions until all pods turned brown. Both desiccant s adequately desiccated alfalfa for harvesting but desiccation with gl ufosinate took 2 or 3 d longer than diquat. Desiccants did not reduce alfalfa growth in the spring after application.