EFFECTS OF HERBICIDES AND THEIR APPLICATION TIME ON ALFALFA FORAGE PRODUCTION

Abstract

Dichlobenil at 2 kg ha−1 yearly increased alfalfa (Medicago media Pers. ’Beaver’) forage yield by 17% over 4 yr, and controlled narrow-leaved hawk’s-beard (Crepis tectorum L.) and dandelion (Taraxacum officinale Weber). Terbacil increased forage yield by 5% in spite of damage to the alfalfa immediately after application in spring and at 2 kg ha−1 suppressed growth of bromegrass (Bromus inermis Leyss.) and crested wheatgrass (Agropyron cristatum (L.) Gaertn.). 2,4-D controlled only narrow-leaved hawk’s-beard, damaged alfalfa moderately to severely, reduced yields, but increased forage protein and phosphorus levels some of the time. There were no significant differences in yield between fall and spring applications of herbicides.Key words: Alfalfa, simazine, 2,4-D, dichlobenil, terbacil, napropamide