Received for publication 4 Apr. 1985. The expert technical assistance of Nancy Adams and the financial support of the New York State Grape Production Research Fund are gratefully acknowledged. The helpful comments and suggestions of M.H. Roberts, S.K. Kim, T. Robinson, and R.M. Pool are deeply appreciated. Picloram was a gift from the Dow Chemical Company. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.