Ascochyta blight of Lentils

Description. All above ground plant parts of lentil plants can be affected by ascochyta blight. Symptoms may appear on plants from the seedling to mature stages. The disease appears as spot- like lesions which are initially light grey, but become tan with a dark brown margin.
The centres of lesions become speckled with pycnidia (tiny, dark fruiting bodies). The presence of pycnidia is the best way of identifying ascochyta blight lesions from those caused by other diseases such as botrytis grey mould or stemphylium blight. Heavy infestations of ascochyta blight will cause premature leaflet drop and stem dieback at the growing tips giving plants a blighted appearance.
Pod infection can lead to seed infection and discolouration of the grain. Infected seed generally has brown patches on the seed surface, but may show no symptoms at all. Compared to healthy seed, heavily infected seed is purplish- brown, shrivelled and reduced in size.
Disease Cycle. The fungus may either be seed-borne or survive on infected stubble from previous diseased crops. While the disease can become established as a result of sowing infected seed, it may also infect new crops when spores of the fungus, produced on infected stubble are carried by the wind from old lentil paddocks. Infection can occur at any stage of plant growth; however, moisture is essential. Cool wet weather promotes sporulation, spore dispersal and infection. Secondary spread within crops occurs when spores produced on diseased plants are carried by wind and rainsplash onto neighbouring plants. Heavy rainfall late in the season provides ideal conditions for pod infection and subsequent seed discolouration.