Didymella pinodes

Didymella pinodes is a fungal pathogen that primarily affects pea crops. It is the causal agent of the disease commonly known as Ascochyta blight, one of the most destructive diseases of peas worldwide.

Taxonomy

The fungus was first described in 1927 by the mycologist Hans Wilhelm Wollenweber and has since been reclassified several times. It is currently placed in the genus Didymella, which is part of the family Didymellaceae in the order Pleosporales.

Description

Didymella pinodes is a necrotrophic fungus, meaning it kills host tissue and then feeds on the dead cells. It produces small, dark, flask-shaped fruiting bodies called pycnidia, which contain numerous spores. These spores are spread by wind and rain splash, and can survive in soil and crop debris for several years.

Disease cycle

The disease cycle of Didymella pinodes begins when spores land on a susceptible host and germinate. The fungus penetrates the plant tissue, causing lesions and tissue death. The fungus then produces more spores, which are released and spread to new hosts. The disease cycle can occur multiple times in a single growing season.

Management

Management of Didymella pinodes involves a combination of cultural practices, chemical control, and breeding for resistance. Cultural practices include crop rotation, sanitation, and avoiding overhead irrigation. Chemical control typically involves the use of fungicides. Breeding for resistance is a long-term strategy that involves selecting and breeding pea varieties that are less susceptible to the disease.

Impact

Didymella pinodes has a significant impact on pea production worldwide. It can cause yield losses of up to 50% in severe cases. The disease also reduces the quality of the harvested peas, which can affect their market value.