Effects of 2,4-D, Dicamba and 2,4,5-T on Creeping Red Fescue Seed Production

The effects of 2,4-D [(2,4-dichlorophenoxy) acetic acid] or 2,4,5-T [(2,4,5-trichlorophenoxy) acetic acid] at 0.56 and 1.12 kg/ha and of dicamba (3,6-dichloro-o-anisic acid) at 0.14–0.56 kg/ha on the seed production of creeping red fescue (Festuca rubra var. genuina L.) were evaluated. Mid-September applications as low as 0.56 kg/ha 2,4-D to fescue in the year of seeding severely reduced yields the following year. Applications of 1.12 kg/ha 2,4,5-T at the same time reduced yields in 1 of 2 yr. Yields of 1-yr-old fescue were reduced by spring applications of 1.12 kg/ha 2,4-D made at or before the 50% heading stage and 0.56 or 1.12 kg/ha 2,4,5-T made prior to stem elongation or at the shot-blade stage. Similar application of 2,4,5-T at the 50% heading stage did not reduce yields. Severe yield reductions occurred when 0.70 kg/ha 2,4-D was applied at the heading to the 90% flowering stages, but not when applied at the hard dough stage. Dicamba had no effect on the yields obtained the year following seeding, regardless of whether applied in mid-September or in the spring prior to the 50% heading stage. Dicamba or 2,4,5-T had no major effect on seed quality, but applications as low as 0.56 kg/ha in mid-September increased dockage the following year. Applications of 0.70 kg/ha 2,4-D at the flowering stage during the year following seeding increased dockage and severely reduced both seed weight and germination.