PIRICULARIA ORYZAE CAVARA
ARMY BIOLOGICAL LABS FREDERICK MD
Pagination or Media Count:
Rice blast occurs in the neck, nodes of the stem, branches of the spikes, and in the area soon after the spikes emerge. The so-called white spikes and withered palea can occur. The color of the spots which are formed in the first stage of the disease can be contrasted with the case of the leaves. By the time that they are noticed in the fields, the disease has progressed considerably and the spots are light black on the spike neck, completely black on the nodes, and white or grey on the spike branches and the paleas. If attacked soon after they emerge, the spikes which have been attacked will not bear any fruit, but if they are not attacked immediately, but two weeks later, the progress of the disease is slow and some ripe fruit does occur. Spike and node blast occurs most severely when too much fertilizer has been applied or if they have been immersed in cold water. Neck and node blasts are very common in the mountains of northern Japan and palea and spike branch blast can be seen throughout the country.