RICE BLAST
Symptoms
Blast symptoms can occur on leaves, leaf collars, nodes and panicles. Leaf spots are typically elliptical (football shaped), with gray-white centers and brown to red-brown margins. Fully developed leaf lesions are approximately 0.4 to 0.7 inch long and 0.1 to 0.2 inch wide. Both the shape and the color vary depending on the environment, age of the lesion and rice variety. Lesions on leaf sheaths, which rarely develop, resemble those on leaves.
The most serious damage occurs when the fungus attacks nodes just below the head. The stems often break at the diseased node. This stage of the disease is referred to as “rotten neck.” Disease in the node prevents the flow of water and nutrients to the kernels and they will stop developing. Heads of plants damaged in this way may be completely blank to nearly normal, depending on the stage of head development when infection occurs. The poorly developed grain usually breaks up badly in milling, reducing quality.
