2 Department Circular 383, U. S. Dept, of Agriculture 
year later, when one of the first publications on this disease appeared, 
‘it was evident that a serious problem was at hand, a problem in- 
volving the future welfare of our great American chestnut forests. 
The onsweep of the devastating bark disease is a matter of history. 
It spread rapidly through all the chestnut regions of the eastern 
United States and, according to specialists.in the department, has 
now reached the southern limit of commercial chestnut growth in 
northern Georgia and northwestern South Carolina. It appears from 
all the evidence at hand that it is only a question of a few years when 
our former great chestnut forests will be extinct and we shall have 
to look elsewhere for materials to meet the needs this valuable tree 
has in the past provided. While the blight was devastating the 
chestnut forests, orchards of chestnuts in the New England and 
Middle Atlantic States were also wiped out, so that there is no 
longer any orchard culture of consequence east of the Allegheny |. 
Mountains. 
When it first became evident that the chestnut blight was a menace 
of the first magnitude, renewed interest was aroused in forei 
explorations for. the purpose of discovering new forms that mipht be 
of use in meeting the situation. From 1903 to 1912 numerous lots 
of Chinese and other chestnuts were received, grown, and dis- 
tributed in the course of the foreign plant introduction work. Mean- 
while the origin of the chestnut-blight fungus remained unknown, 
and it was not until the spring of 1913 that it was discovered in 
China under conditions that left no doubt that its original home 
had been found. The discovery was made'by the late Frank N. 
Meyer, agricultural explorer of the Bureau of Plant Industry, United 
States Department of Agriculture. He found the disease attacking 
the Chinese hairy chestnut (Castanea mollissima), and also evidence 
that this chestnut was resistant in varying degrees. From 1913 until 
the present time the search in foreign fields for blight-resistant 
chestnuts and related species has continued. ; é 
In 1921 J. F. Rock began systematic work in agricultural explo- 
rations for the Bureau of Plant Industry, United States Department 
of Agriculture, that year confining his activities mainly to Siam 
and Burma. In August, 1922, Mr. Rock undertook an extensive 
and detailed search for new chestnuts and related species in the 
Province of Yunnan, western China. This Province lies north of 
Siam and on the northeastern border of India. The country is 
difficult of access. It is a region of magnificent mountains, high 
plains, large and small valleys, deep gorges, and rushing waters. 
The climate is unlike anything in this country, subtropical in the 
lowlands, with clouds, fogs, and snows on the high elevations, with- 
which the country abounds. At the higher elevations, 5,000 to 
sed feet, the winter temperatures are not low, but the snows are 
eavy. 
_ Mr. Rock spent. several weeks in the primeval forests of this 
interesting region, collecting large quantities of seeds, which were 
carefully packed and started on their long and hazardous journey 
late in the fall. After many vicissitudes the seeds reached Wash- 
ington, closing a chapter of one of the most extensive undertak- 
ings of the kind on record. Mr. Rock remained in the.region 
through the winter, spring, and summer of 1923, and was enabled 
