SPREAD OF RICE BLAST IN SMALL FIELDS
ARMY BIOLOGICAL DEFENSE RESEARCH CENTER FREDERICK MD
Pagination or Media Count:
Increase and concurrent spread of rice blast from foci in small fields is described under nearly ideal conditions for infection. Lesion counts and severity estimates were made at stations on polar coordinates at regular intervals. Spore loads in the air were measured with rotobars uniformly spaced aroundthe foci andcorrected to spore hours per cubic meter. Increase in the air are shown. Lesions were present six days after inoculation. Growth of foci in all fields was similar and logarithmic notwithstandng initial size. Toward the end of the epiphytotic, spore load decreased faster than disease attenuated. In early stages of an epiphytotic, when 40 or fewer lesions occur per acre, there is little chance of detecting spores on a rotobar.
- Agronomy, Horticulture and Aquiculture