Fusarium head blight

Pathogen and disease type. The pathogen Fusarium graminum (commonly associated with the Fusarium graminearum species complex) is a destructive ascomycete fungus. It is responsible for various plant diseases, including seedling blight, crown rot, and the most economically significant form, Fusarium head blight (FHB). The fungus survives in crop residues and soil, producing inoculum that triggers epidemics under favorable conditions.

Affected crops and economic impact. The disease primarily affects small grain cereals such as wheat, barley, rye, oats, and maize. The economic impact is twofold: yield loss through grain shriveling and reduced crop quality, and the accumulation of hazardous mycotoxins like deoxynivalenol (DON). Contaminated grain often fails safety standards, leading to significant financial losses for producers.

Symptoms and signs. The characteristic sign of the disease is the premature bleaching of spikelets on an otherwise green head. In humid conditions, a salmon-pink or orange fungal growth can be observed on the glumes and spikelets. Infected kernels are often thin, shriveled, and may show a white or pinkish mycelial covering, leading to poor germination and establishment in subsequent seasons.

Development and spread. The fungus thrives in warm, humid weather, especially during the flowering (anthesis) stage of grain development. Spores are dispersed via rain splashes and wind currents. High humidity and prolonged leaf wetness create an ideal environment for the fungus to penetrate the floral parts, allowing for rapid colonization of the developing grain.

Management and prevention. Controlling FHB requires an integrated management strategy aimed at reducing inoculum and protecting the head during the critical flowering window. Key measures include:

• Crop rotation with non-host species to reduce the levels of pathogen inoculum in the soil.
• Effective tillage practices to bury crop residues where the fungus persists.
• Use of certified, fungicide-treated seeds to ensure healthy stand establishment.
• Selection of resistant or tolerant cultivars suitable for the local climate.
• Application of specialized fungicides at the early flowering stage when weather conditions favor infection.