Published online by Cambridge University Press: 12 June 2017
Clethodim was applied to tall fescue to determine the effects of application timing (fall, early spring, mid-spring), rate (0, 5.6, 11.2, or 22.4 g ai ha−1), and use of crop oil (0 or 2.3 L ha−1) on seedhead density and forage yield and quality of tall fescue. Increasing the rate of clethodim or adding crop oil reduced seedhead density and forage yield, and generally improved forage quality. There was no effect of application date in 1988 and 1990, but seedhead density and forage yield decreased from the November to the March application date in 1989.