Published online by Cambridge University Press: 12 June 2017
Leafy spurge viable seed production and germination were reduced by 2,4-D applied during flower development and seed formation, in the field. Viable seed production was reduced when 2,4-D was applied at all growth stages after the start of flower bud development. The number of viable seed from untreated plants was 173, while, the number of viable seed from plants treated 0, 7, 14, 21, 28, or 35 d after the start of flower bud development was <1, 4, 7, 31, 53, and 62; respectively. Leafy spurge seed germination was higher in gibberellic acid than in water for seed collected from untreated plants and from plants treated with 2,4-D 7, 14, and 21 d after bud initiation. This research shows that 2,4-D must be applied prior to flower bud development to prevent seed production.