Studies on a fungus causing a leaf blotch disease on peas (Pisum sativum L.)

Abstract

The pea crop is classified as one of the principal field crops in New Zealand according to the New Zealand Official Yearbook (1945). Over the last five years, although there has been an increase in the total yield, the yield per acre has decreased considerably. This decrease in yield per acre is probably due to a number of causes, among which losses due to disease are known to play an important part. There are a number of diseases which affect the pea crop in New Zealand and cause fairly extensive damage. In addition to major foliage diseases there are a number of minor diseases which, given favourable environmental conditions, may cause considerable damage to pea crops. Into this latter category falls the disease which has been chosen for this particular study. The name given to this disease where it has occurred overseas is Septoria blotch, Septoria blight, Septoria leaf-blight, or just leaf-blight. The causal organism is Septoria pisi Westend.