Host Induced Change in the Morphology of a Powdery Mildew Fungus

Abstract

BLUMER'S¹ work showed that the powdery mildews produce two types of conidiophore, those of the Erysiphe polygoni DC. type, producing one mature conidium in a day, and those of the Erysiphe cichoracearum DC. type, producing a chain of between two and eight mature conidia in a day. Childs² later referred to these two powdery mildews as the non-chain forming and the chain forming types respectively. He showed that the former had a single peak period of spore liberation between 1000 and 1400 h, while the latter had a more complex diurnal cycle of spore liberation with two peaks, the first between 0600 and 0800 h and the second between 1400 and 1600 h. There is no evidence that the fungus which produces one type of conidiophore can produce the other in any circumstances.