Received for publication 4 Apr. 1985. Scientific Paper No. SP-7078, College of Agriculture, Washington State Univ. We acknowledge the gift of PP333 from ICI Americas, Inc., and thank Roger Couture, Senior Plant Physiologist, for providing information about this product. 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.