WHITE-PINE BLISTER EUST. 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 relativel}^ 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 nurser}^ trade domi- 

 nated the situation and prevented such action. 



Since the disease on Ribes plants is essentially one of the loaves, 

 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 Boixieaux 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 

 Oronartium rihicola 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 



