218 MANUAL OF FRUIT DISEASES 
diseased ; for there is a slight possibility of their carrying the 
blister-rust fungus over winter. 
Considerable effort has been made to date to control the dis- 
ease with reference to the five-needle pines. So far, however, the 
work has not been wholly successful. The difficulties involved 
are these: (1) There has never been any attempt previously, 
in Europe or America, to eradicate a tree-fungus of this sort; 
so there is no past experience on which to base the procedure. 
(2) The fungus incubates, or lies dormant without showing 
itself externally, for a period varying from one to six or more 
years; thus inspection has been inefficient. Diseased trees 
have been overlooked. (3) Neither the federal nor the various 
state officials who must carry on this inspection have the power 
to destroy the currants and gooseberries found within the 
danger zone. (4) The people generally do not realize the 
seriousness of the blister-rust disease, and therefore cooperation 
has not been unanimous. 
With the knowledge of the disease now available it seems 
likely that rational measures may be employed even in the 
absence of previous experience. On account of the long in- 
cubation period of the fungus in the pine, annual inspections 
are necessary, unless, of course, the whole group of pines be de- 
stroyed immediately on discovery of the disease. Special 
emphasis is laid on the destruction of wild currants and goose- 
berries, for the uredospores may spread from plant to plant for 
many miles during the summer. There is great need for ade- 
quate state laws. Inspectors should be regarded as friends of 
the people rather than as personal enemies to the fruit-grower 
or the forester. Their presence should be taken as an index of 
precaution against calamity rather than of any ill-influence of 
a supposedly antagonistic citizen. Such officers not only need 
cooperation, but, unfortunately, as experience has shown, they 
need legal power to compel concerted action in the eradication 
of diseased plants. In most cases the removal of currants and 
