Mycosphaerella graminicola

Mycosphaerella graminicola, also known as Septoria tritici blotch (STB), is a fungal pathogen that primarily affects wheat crops. It is one of the most destructive diseases of wheat, causing significant yield losses worldwide.

Taxonomy

The fungus was first described in 1884 by Heinrich Friedrich Link, a German naturalist and botanist. It was initially classified as Septoria tritici, but was later reclassified as Mycosphaerella graminicola due to its sexual stage. The species belongs to the Mycosphaerellaceae family in the Ascomycota phylum.

Description

Mycosphaerella graminicola is a filamentous fungus. It produces ascospores in structures called pseudothecia, which are dark, spherical and embedded in the host tissue. The fungus also produces pycnidia, which are flask-shaped structures that contain asexual spores or conidia.

Disease Cycle

The disease cycle of Mycosphaerella graminicola is complex and involves both sexual and asexual reproduction. The fungus overwinters as pseudothecia or pycnidia on infected wheat debris. In the spring, ascospores or conidia are released and dispersed by wind to infect new wheat plants. The fungus penetrates the plant tissue, causing lesions and blotches on the leaves. The fungus then produces new pseudothecia or pycnidia in these lesions, completing the disease cycle.

Management

Management of Mycosphaerella graminicola involves a combination of cultural practices, chemical control, and breeding for resistance. Cultural practices include crop rotation and removal of infected plant debris to reduce the source of inoculum. Chemical control involves the use of fungicides. Breeding for resistance is a long-term strategy that involves the development of wheat varieties that are resistant to the fungus.

Impact

Mycosphaerella graminicola causes significant yield losses in wheat crops worldwide. The fungus reduces the photosynthetic area of the plant, affecting grain fill and reducing yield. In addition, the disease can reduce the quality of the grain, affecting its market value.