I 50 ^ ^1»- ra m—^- '> 7' (^ M^ W- j5Ji 



Messrs, S. Tujita and J. Kasahara of the Company struck with the seriousness of 

 the case at once took active measures to combat the disease. By thoroughly spray- 

 ing with the Bordeaux mixture and by systematic picking of the affected leaves, 

 they were able to prevent the spread of the disease for the rest of the year. 



The fungus in question seems to be peculiar to Japan, as there are no records 

 of the occurrence of the downy mildew on the hop-vines cither in Europe or 

 America, for such a destructive parasite on such an important crop is scarcely likely 

 to have passed unnoticed there. 



In August of 1905, Mr, J. Hanzawa, an assistant professor of botany in the 

 Sapporo Agricultural College, found on the Avild hop- vine, Hitmuhts Lnpiihis L. 

 var, cordifoUus Maxim, the same fungus at Zenibako about 12 miles from Sapporo. 

 At about the same time, Prof. G. Yamada of the Morioka Agricultural and Dendrol- 

 ogical High School also collected the same parasite on the same host in the xicinity 

 of Morioka in Northern Honshu. These facts prove beyond doubt, that the mildew 

 fungus is indigenous to this country growing on the wild hop-vine, and has recently 

 found a more congenial host in the cultivated- hop-vines introduced from America 

 and Europe. 



The diseased leaves show^ at first small yellowish spots limited by the veinlets 

 and scattered irregularly over their surface. Finally these spots become confluent 

 often forming large irregular brownish or dark brown patches. On the undersurface 

 of the leaf at the discolored portion is formed a thick downy growth, which is 

 whitish at first but later turns to dark gray. The leaves having large affected 

 spots along their margin or midrib show occasionally conspicuous bullations in the 

 adjoining green portion of the blade. 



From two to five conidiophores spring out of a stoma. Their length is variable, 

 ranging from 200 to 460 /-/, sometimes attaining even 600 11. They are slightly 

 swollen at the base ; and their average diameter at about the middle is d-j pt. 

 The first branching takes place at about 2/3 or 3/4 from the base. The branch 

 system is 5-6 times dichotomous and rather spreading ; and its ultimate branches 

 are either straight or slightly curved inwards or occasionally outwards, tapering 

 to a blunt point. 



Conidia are broad elliptical or obovate, 22-26 /a long and 15-18 // broad, of 

 a light smoky color, and with a lighter colored or colorless blunt apical papilla 

 (1.5-2 fx in height and 4 u. in breadth). The thickened septum of the conidium 

 often remains as a short papilla at its base, but generally it dissolves away when it 

 is mounted in water. The germination takes place in about three or four hours. 

 The contents break up into about eight zoospores, w^iich escape through an open- 



