Identity, taxonomy and seed-borne aspects of the gray leaf spot organism on blue lupin : a thesis submitted in partial fulfilment of the requirements for the degree Master of Agricultural Science at Massey University

Abstract

While conducting studies in the Manawatu on the brown spot disease of blue lupins 1/ caused by Pleiochaeta setosa (Kirchn.) Hughes, Milne (1964) frequently encountered a Stemphylium disease characterised by necrotic lesions on leaves, stems and pods. A disease caused by a species of this genus had not previously been reported on blue lupins in New Zealand, but in the United States of America Wells, Forbes, Webb and Edwardson (1956) described two previously unrecognised diseases on this host, namely "little leaf spot" caused by Stemphylium botryosum Wallroth and "gray leaf spot" caused by S. solani Weber. Milne considered his isolates to be S• botryosum but was confused by the symptoms being typical of those recorded for S.solani (gray leaf spot). He did not pursue the matter further and at the completion of his studies on P• setosa there remained the unresolved question of the identity of the Stemphylium species present on blue lupin in the Manawatu. [From Introduction]