Nigrospora ear rot

Khuskia oryzae, widely recognized by its anamorph name Nigrospora oryzae, is an ascomycete fungus classified within the Apiosporaceae family. As a significant phytopathogen, it is distributed globally, particularly in tropical and subtropical regions where environmental conditions favor the rapid proliferation of fungal infections in cereal crops.

This fungus is primarily known as the causal agent of Nigrospora ear rot. While rice is the most economically important host, Khuskia oryzae frequently infects maize, sorghum, and several other grasses. The infection manifests as the colonization of plant tissues by dense, black, velvet-like fungal masses consisting of conidia, which disrupt the normal development of kernels and stalks.

The life cycle of Khuskia oryzae begins with the survival of the fungus on crop residues and infected debris. Under favorable conditions, the pathogen produces abundant spores that are dispersed through rain splashes and wind currents. These spores enter the plant tissue through natural openings or wounds caused by insect damage or environmental stress, initiating the colonization process.

The development and spread of the disease are highly dependent on high humidity and warm temperatures, typically ranging from 25°C to 30°C. Prolonged periods of rainfall during the grain-filling stage exacerbate the severity of the infection. Crops that are weakened by nutritional deficiencies or drought stress are particularly susceptible to the rapid advancement of the mycelium throughout the host plant.

• Reduction in seed germination rates and seedling vigor.
• Structural degradation of the grain, affecting commercial quality.
• Development of internal rot that often goes undetected until harvest.
• Yield losses occurring both in the field and during post-harvest storage.

Effective management and control of Khuskia oryzae require an integrated approach. The most critical measures include crop rotation to break the pathogen's life cycle and the removal or deep incorporation of crop residues into the soil. Seed treatment with appropriate fungicides is essential to protect young plants. Additionally, maintaining optimal storage conditions with low humidity is vital to prevent the spread of the fungus in grain warehouses.