What disease affects rice and is caused by a fungus?

Rice blast is a significant disease affecting rice, caused by the fungus Magnaporthe oryzae. This pathogen can lead to severe yield losses if not properly managed. The disease is characterized by distinct symptoms that include lesions on the leaves, neck, and grains of the rice plant. Infected areas exhibit grey-green spots that can expand into larger lesions, often resulting in a characteristic "blasted" appearance of the panicle, where grains fail to develop.

In contrast, while Fusarium wilt and leaf spot diseases do impact various crops, they are not specific to rice or caused by the same pathogen associated with rice blast. Aggregate sheath spot is another rice disease, but it is caused by a different pathogen and has different symptoms compared to rice blast. Therefore, rice blast is the correct choice, as it directly addresses the fungus that specifically affects rice.