- Experiments in Corvallis, OR and Pasco, WA evaluated the potential of bicyclopyrone, tolpyralate, halosulfuron and EPTC for weed control in carrots. Bicyclopyrone and tolpyralate significantly reduced plant stand, injured carrots, and reduced yield at all three rates. Only bicyclopyrone at 0.875 oz/A and tolpyralate at 1 oz/A provided yield within range of linuron, prometryn, and EPTC treatments. The prometryn treatment yielded the most carrots, followed closely by linuron and EPTC. Halosulfuron killed all carrots. Weed control with bicyclopyrone and tolpyralate was similar when comparing within treatments with equal carrot injury. A possible exception was that tolpyralate may have controlled crabgrass better than bicyclopyrone. Prometryn control of hairy nightshade lasted longer than linuron.