Newly seeded alfalfa tolerated glyphosate applied from the 8-trifoliolate leaf stage (17 cm tall) to the pre-bud stage (34 cm tall) at 75 or 150 g ae ha-1. Injury symptoms were moderate and temporary. Glyphosate at 300 g ha-1 suppressed alfalfa severely and killed 30% of the plants when applied at the smallest (3-trifoliolate) stage of alfalfa growth. Alfalfa responded similarly to glyphosate and SC-0224.

Established alfalfa treated with glyphosate at 75 or 150 g ae/ha (rates known to control dodder) during the vegetative or bud stage showed symptoms of narrowed leaves and mildly chlorotic new growth, and yield of one cutting of alfalfa usually was reduced by 10 to 20%. Glyphosate, applied in the vegetative stage, affected the treated foliage more than postharvest regrowth. Applied at bud stage, the regrowth that followed harvest of treated foliage was affected more. Symptoms and effect on yield were greater at 300 g ae/ha, but alfalfa always recovered. Applying glyphosate at 75 or 150 g ae/ha in each of two or three sequential cuttings showed no cumulative effect. Glyphosate and SC-0224 had similar effects on alfalfa and suppressed alfalfa much less than would a severe infestation of dodder.

Glyphosate and SC-0224, at rates that control dodder (75 to 150 g ae ba–1), injured flowers, caused flowers to abscise, and sometimes reduced seed yields when applied to alfalfa when buds or blooms were present. Glyphosate at 75 or 150 g ha–1 did not injure flowers, impair seed set, or reduce yield or quality of seed when applied to alfalfa foliage before the bud stage.