ON THE INVASION OF ROOTS OF MEDICAGO AND MELILOTUS BY SCLEROTINIA SP. AND PLENODOMUS MELILOTI D. AND S.

Abstract

The invasion of roots of Medicago and Melilotus by Sclerotinia sp. and P. meliloti was studied, with particular reference to the effectiveness of wound cork in arresting the progress of these pathogens. Both pathogens are apparently capable of penetrating through the uninjured external cork covering of the roots and also through any subsequently formed wound cork layers. Killing of the root tissues and retardation of wound cork development in advance of hyphal invasion was caused by both pathogens. No explanation can at present be offered as to why the advance of P. meliloti is checked and that of Sclerotinia sp. is definitely slower after good growth begins in the spring.