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This is an introductory paper on the outbreak of fungal disease Scieroderris canker of Todo-fir in Hokkaido, northern Japan. Scicroderris canker, caused by Scieroderris lagerbergii Grem., broke out in 1970 in several localities of the northern Japan. A remarkable characteristic of this disease is that it damages no shoot above the surface of deep snow cover. It was found that the site selection and methods for reforestation are the most important factors that can facilitate escape from Scieroderris canker.

Both sericultural and manufacturing branches of Japan's once highly important raw silk industry suffered severe dislocations following peak production about 1930. World economic depression, synthetic fiber development, and World War II were fundamental causes. Reeling mill closures stemmed from bankruptcies, governmental readjustment programs, conversions into defense plants, bombings, and post-war business rationalization, Mulberry acreage shrank principally owing to wartime food shortages and profitable post-war alternatives, particularly orcharding. This paper contrasts changes observed in two of the most specialized Japanese cocoon-producing regions, Gumma Prefecture, on the Kant&obar; lowlands where sweet potatoes and upland rice characteristically followed mulberry, and the Nagano Basin, representative of highland basins in central and northern Honshu, where orchards common replaced mulberry. Proportional losses in both reeling capacity, measured in number of reeling machines and in mulberry acreage were above the national average in the Nagano Basin and below it in Gumma Governmental policies and local factors caused these differences. [ABSTRACT FROM AUTHOR]