Chemical Weed Control in Tall Bearded Iris

Fall-applied 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine) and α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) satisfactorily controlled annual and biennial weeds in tall bearded iris (Iris germanica L.). Increased application rates improved control of semitolerant weeds. Trifluralin controlled grass weeds better than simazine. Simazine caused leaf tip and root necrosis, and trifluralin prevented root growth of iris plants when incorporated in the root zone at high rates of application.