Mollisia blight

Mollisia blight is a fungal disease caused by species within the genus Mollisia. These ascomycete fungi are often associated with stem and root rot symptoms in various agricultural crops. While they frequently act as saprotrophs on plant debris, under specific environmental conditions, they can become necrotrophic pathogens, causing significant stress to host plants.

The disease primarily affects cereal crops, including wheat, barley, and rye, but can also colonize grasses. The infection cycle often begins at the base of the plant, utilizing moisture trapped in the lower canopy. By infecting the stem base and leaf sheaths, the fungus disrupts the plant's ability to transport nutrients effectively, leading to stunted growth.

Diagnostic symptoms typically include the development of necrotic lesions on leaf sheaths and stems, which often appear greyish or brown with dark edges. During periods of high humidity, the characteristic apothecia—small, cup-shaped fruiting bodies—develop on the surface of dead or dying tissue, releasing spores that continue the infection cycle.

The development and spread of Mollisia are heavily dependent on environmental factors, particularly cool, wet weather. Excessive soil moisture and dense planting configurations create a stagnant microclimate that promotes rapid spore germination and colonization. Wind and rain splash serve as the primary vectors for transporting inoculum from infected crop residue to healthy plants.

The economic impact of this disease is significant, as it can cause reduced crop vigor, susceptibility to lodging, and ultimately lower grain quality and yield. Effective management requires an integrated approach to maintain crop health and reduce pathogen pressure. Recommended strategies include:

• Implementation of crop rotation cycles to break the infection path.
• Removal or deep incorporation of crop residues to reduce primary inoculum.
• Optimal seeding rates to ensure good aeration within the crop canopy.
• Timely application of systemic fungicides if threshold levels are exceeded.