This paper discusses the results of preliminary tests for determining the best way to kill the potato vine under the conditions of the State of São Paulo. Of the methods compared (cutting or flaming the vines, or spraying them with sodium chlorate, sodium arsenite, dinitro cresol or dinitro-o-sec-butyl phenol), spraying with the dinitro derivatives seemed to be the best. Further experiments are needed to observe the incidence of virus diseases and rots caused by Phytophthora infstans and Alternaria solani in the seed potatoes coming from fields treated with the latter products.