DEVELOPMENT OF RHIZOCTONIA-SOLANI KUHN ON THE UNDERGROUND PARTS OF THE POTATO PLANT

The development of the sclerotia (black scurf) of Rhizoctonia solani Kühn, on potato tubers is related to tuber maturity and the health of the root and stolon systems. Few sclerotia formed on tubers from untreated plants until the onset of plant senescence when, as the tubers matured and roots and stolons decayed, sclerotia developed both rapidly and extensively. Application of acid to haulms in early August led to an increase in black scurf on tubers, initially related to the increase in root and stolon infection, but especially after later harvests, to the degree of tuber maturity. Later in August, scurf increases were paralleled both by tuber changes and root and stolon infection. My mid-September, when acid application was to plants becoming senescent, there was little difference between patterns of infection found on treated and check plants. © 1979 Kluwer Academic Publishers.