SOME FACTORS AFFECTING THE OCCURRENCE AND DEVELOPMENT IN POTATOES OF GANGRENE CAUSED BY PHOMA SOLANICOLA PRILL. & DELACR.

It is shown that gangrene is a soil- and haulm-borne disease and that infection of the tubers can take place through cuts, bruises, 'eyes' and lenticels. Low temperature and dry, dark storage were found to be most favourable to development of the disease, but rotting was more severe if the tubers had been kept at a higher temperature before infection took place. Storage at 21 degrees C. for 10 days was sufficient to arrest rotting. Gangrene developed on all the potato varieties tested, but different varieties showed differences in susceptibility to the disease. No difference was observed in the susceptibility of early and late varieties but susceptibility increased with advancing maturity of the tubers.