Miyajima

Miyajima is a specific pathogenic complex, most often associated with fungal diseases affecting rice and other cereal crops in the Asian region. Although the term «Miyajima» is frequently encountered in specialized literature within the context of breeding lines affected by specific mycoses, it is classified as a biological agent that causes systemic metabolic disorders in plants.

Systematically, this pathogen belongs to the kingdom Fungi. Depending on the specific strain, it can affect the vascular system or the foliar apparatus, triggering the development of spots or wilting. This pathogen is an obligate parasite closely linked to the life cycle of its host crops, which makes its control an extremely difficult agronomic task.

The biology and life cycle of the pathogen are closely related to the hydrothermal regime of the environment. The spores of the pathogen are spread mainly by water droplets, wind, or through contaminated seed material. Upon germinating on the plant surface, the mycelium penetrates the tissues through natural openings or mechanical injuries, after which it begins active vegetative development in the intercellular spaces.

Conditions for the pathogen's development include high air humidity (over 85%) and moderately high temperatures in the 22–28°C range. Such weather parameters contribute to the rapid accumulation of the infectious background. The spread of the disease in crops occurs in foci; however, under favorable conditions, the infection can cover up to 60–80% of the field area in a short period of time.

Harmfulness manifests as a significant reduction in yield, caused by the suppression of photosynthetic activity and the disruption of nutrient transport. The results of the infection include grain shriveling, reduced seed quality, and general degradation of vegetative mass. To protect crops, complex control methods are employed:

• The use of certified, treated seed material.
• Adherence to crop rotation, excluding susceptible cultures.
• Implementation of preventive treatments with systemic fungicides during critical growth phases.
• Regulation of plant density to improve crop ventilation.