WHITE-PINE BLISTER RUST. 77 
eradication was impossible. Local control has therefore been the 
only aim of the Europeans. Besides all this, the application of 
methods of control to plant diseases in Europe has never been devel- 
oped to such a point as it has in North America except for relatively 
few diseases of the more important cultivated crops. There has 
apparently never been a well-planned investigation of the control 
of this disease extending over a number of years anywhere in Europe. 
All European publications upon control are fragmentary. It. is 
evident that many scattered efforts have been made to control the 
disease there, but the results have never been published. 
As stated above, the status of Pinus strohus in Europe is entirely 
different from its status in North America. While it has been more 
than 200 years since it was introduced into Europe (5) , it of course 
has not approached the distribution that a tree does in its native 
region. It has been widely distributed in Europe as a park and orna- 
mental tree and has been very popular for this purpose. As a forest 
tree it is a species which is planted in relatively small blocks and even 
then only on an experimental scale. In Europe it is essentially an 
ornamental tree rather than an important timber tree. Its total 
value there is -exceedingly small compared to its total value in North 
America. 
Legislation against plant diseases in Europe is so complicated that 
no attempt will be made here to give an outline of it. Incidentally, 
it should be stated that Tubeuf (162, 163, 164, 169, 170, 174) has 
repeatedly called attention to the fact that commercial nurseries 
have been and are still spreading this disease throughout Germany. 
In 1904 he (170) repeats earlier demands for a national control of 
the forest-tree nursery trade and goes so far as to refute the state- 
ments of Schwarz (125) that this disease in the nurseries at Halsten- 
bek is absent or negligible. It is evident that the nursery trade domi- 
nated the situation and prevented such action. 
Since the disease on Ribes plants is essentially one of the leaves, 
there has been an apparent chance for success by spraying them. 
Tubeuf (165) seems to have been the first to report on such tests. 
He sprayed Ribes leaves in the greenhouse with Bordeaux mixture 
and then set the sprayed plants among those already diseased. 
Numerous uredinia soon developed on the lower sides of the sprayed 
leaves. Jaczewski (58) says that spraying with Bordeaux mixture 
is not very effective. 
Ewert (37) in 1912, to prove whether infection of Ribes leaves 
always occurs on the lower side only, made a test on a bush of Ribes 
nigrum. This bush was one of a number of Ribes plants upon which 
Cronartium ribicola had appeared every year for a decade. One-half 
of the bush was sprayed on the lower sides of the leaves only; the 
other half was untreated. Spraying was done on March 28, April 9 
