The tolerance of 10 broccoli cultivars to preemergence (PRE) applications of oxyfluorfen was evaluated in greenhouse and field experiments. Differences in tolerance among cultivars were expressed as differences in seedling injury ratings and growth and stand reduction. The cultivars ‘Pinnacle’ and ‘Mercedes’ were most tolerant, ‘Embassy’ and ‘Early Dawn’ were least tolerant, and other cultivars were intermediate in tolerance. Broccoli seedling weights and stand counts averaged across 10 cultivars and oxyfluorfen application rates of 0.125, 0.25, and 0.5 kg/ha were 70 and 81% of control, respectively, for the two fall-planted experiments and 39 and 50% of control, respectively, for the spring-planted experiment. Differences in tolerance among cultivars were less distinct in the cooler spring than in the warmer fall season. Oxyfluorfen application that caused stand and early growth reduction did not always affect broccoli head weight or quality or delay harvest.
