Stemphylium disease of asparagus (Asparagus officinalis l.) in new zealand

Abstract

In New Zealand purple spot of asparagus spears and leaf spot of asparagus fern are caused by Stemphylium vesicarium (Wallroth) Simmons (teleomorph Pleospora sp.). Ascospores and conidia were both trapped above asparagus crops during the spear and fern growing season, September-May. Numbers of ascospores and the frequency with which they were trapped were low during February-April. In experimental fields of ‘Mary Washington 500W’ annual losses in weight of harvested spears as a result of leaf spot were estimated as ranging from 18 to 51% over a 5-year period. Leaf spot was reduced and yield of spears increased by spraying fern with four applications of chlorothalonil or mancozeb during January-March. In 1986-87 three sprays of captafol applied to fern during January-March were as effective as weekly sprays from December to May in reducing leaf spot and increasing spear yield for three cultivars—‘Rutgers Beacon’, ‘Cito’, and ‘Mary Washington 500W’. © 1992 The Royal Society of New Zealand.