America's Crop Heritage


made by the Bureau of Plant Industry. Subsequently, small test
plantings were made in the South. The crop was publicized
widely as one that could be grown on poor lands. While the
crop has not been grown on a large scale in this country because
of the winter-killing, its production serves as a stimulus to the
Chinese growers to export a good quality of unadulterated oil.
 SUGAR CANE
 The importance of a continuing supply of fresh sugar cane
stocks has not diminished since Charles Mason first secured the
assistance of the Navy in procuring East Indian varieties. Mosaic
disease, a great enemy of Louisiana cane growers, has necessitated
the breeding of new, resistant types. Javanese varieties restored
the industry in Louisiana in the 1920's. But explorers in 1928
had to secure further cuttings for breeding stocks. Over a hun-
dred varieties were found in New Guinea and Papua. In 1935
the Department claimed that the introduction of the mosaic-
resistant varieties had maintained the sugar industry of Louisiana
at an annual value of $20 million, and had saved investments of
$100 million. New threats of mosaic among the resistant varieties
developed in 1935, indicating that further work had to be done.
 Beans were imported from Mexico in 1903 and again in 1945
from Chile, Columbia, Peru, and Mexico to supplement a breed-
ing program. The spineless cacti of Tunis were brought to Amer-
ica in 1905 to test their utility as a feed crop. Thousands of
plants of the Japanese blanched salad vegetable udo, similar to
asparagus, were distributed about the same time. Hemp seed
from Manchuria and China was tried in Kentucky, Nebraska,
and California.
 America began exchanging large numbers of plants with Latin
American countries during the 1930's, and continued the practice
during World War II when plant imports from other lands
were shut off. As an example, cultivation of the Derris elliptica-
the roots of which constitute a source of rotenone-has been
extended by distribution of over 2 million cuttings to Latin
American countries.
 THE WAR YEARS
 When the Japanese invasion spread over plantations of vital
tropical crops in 1942, the Bureau adopted a new program of
self-sufficiency in the Americas. From seed flown in from the


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