THE PROBLEM OF THE IMPORTED PLANT DISEASE 
AS ILLUSTRATED BY THE WHITE PINE 
BLISTER RUST 
HAVEN METCALF 
Bureau of Plant Industry, U. S. Department of Agriculture 
Within the last few weeks the civilized world has stood aghast at 
the stories told by survivors of the devastation wrought by the German 
army in its retreat from Northern France. Particularly schrecklich 
are the stories and pictures showing the rows of fruit trees cut down 
without being utilized for fuel, apparently with no purpose other than 
wanton destructiveness. But if we pause to think we realize that the 
Germans did not do the worst that they could have done. The fruit 
trees are cut down, to be sure, but others can be planted in their places. 
We may expect in future years to see the old orchards completely 
rehabilitated. But let us suppose that instead of simply cutting 
down trees in Europe, any enemy should see fit to leave them standing 
but thoroughly incoulated with diseases which would not only destroy 
the present stand of trees but would prevent their future profitable 
culture in the same territory. To take an extreme example, suppose 
that some malignant person or nation should see fit to introduce into 
Europe from America, the Colorado beetle, the pear blight, the chest- 
nut bark disease, and the citrus canker. Surely the world would stand 
aghast at this if its significance was generally realized, because this 
would not only destroy or seriously damage the present generation of 
plants concerned but would tax the agricultural resources of Europe 
with a perpetual burden. No more fiendish blow to the economic 
resources of a country could be imagined. Yet this is exactly what 
we have allowed foreign nations to do to us without resistance, through 
our lax laws regarding the importation of live plants, or rather through 
our virtual absence of laws on this subject. We have permitted our 
country to be invaded by not one but many—perhaps hundreds—of 
diseases and pests which constitute a permanent tax upon our agri- 
cultural and forest resources, and up to the present time we have made 
scarcely any serious effort to prevent further invasion. 
The Bureau of Entomology has issued a large bulletin entitled 
“A Manual of Dangerous Insects Likely to be Introduced in the 
United States Through Importations.’”’ I understand that this 
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