EFFECTS OF TUBER-BORNE INOCULUM OF RHIZOCTONIA-SOLANI AND FUNGICIDAL SEED POTATO TREATMENT ON PLANT-GROWTH AND RHIZOCTONIA DISEASE IN CANADA AND URUGUAY

Plant growth and the occurrence of rhizoctonia disease on Red Pontiac and Kennebec cultivars were slightly different in Uruguay and Canada. In both countries, use of rhizoctonia-infested seed resulted in some decreases in emergence and stem number and also increased the presence of black scurf on progeny tubers for Kennebec but only in one case for Red Pontiac. Use of the fungicide thiabendazole as a fungicide seed treatment prevented some of these problems but caused some delays in plant emergence and increases in stem numbers. The impact of these and other observations on the export of potato seed are discussed.