Tolerance of Alfalfa (Medicago sativa) to EPTC

Abstract

EPTC (S-ethyl dipropylthiocarbamate) did not reduce emergence of alfalfa (Medicago sativaL. ‘Vernal’) seedlings at 3 to 81 kg/ha in the greenhouse nor at 3 to 243 kg/ha in the field. No rate injured roots, but temporary foliar symptoms were present at all rates. Soaking seeds for 40 days in technical grade EPTC or for 8 days in water saturated with EPTC before seeding in untreated soil did not reduce emergence or injure the seedlings. Seedlings from seeds germinated in paper towels moistened with water saturated with EPTC grew normally when transferred to untreated soil. Alfalfa was injured if seedlings were exposed to EPTC after emergence, but it tolerated exposure to high concentrations during imbibition and germination of the seeds and elongation of the seedlings before they emerged from the soil. EPTC delayed seedling emergence by about 1 day. This effect was separate from that causing typical foliar symptoms.