PLASMOPARA. 



129 



the Vine. This parasite was introduced into Europe from 

 America. 1 It makes its appearance in early summer as white 

 patches on the under surfaces of leaves, sometimes also on stalks 

 and fruit. In the course of the summer the leaves show hrown 

 spots and dry up. 



The white patches consist of tufts of branched conidiophoiv-. 

 from which ovoid conidia are al Dinted. These on germina- 



I-'ni. tO. PtafmOj:"ri' ci'fiVn/c. Ci.ni.|i..]i|i,.i, -. much < nhi 



(v. T'il<nif . 



tion in rain-drops discharge six to eight swarming cell* iV"in 

 \\hi<h germ-tubes i;ro\v into the epidermis df th.' host-plant; 

 thus the di.~' pivad< rajiidly during moist \\ealher and a 



Peronospora riticola, \^'.>n. Magnus, M'//////a,7.-\- Oa 1883. Scribner, 



!:!,., i .,/' U.S. Dept. of .1 ire for ISM;, |,|>. vc, in;, ; thi* 



uiil'lr\\ . A 1 1 irli -, nil i hi- .-nliji -i- 1 iliMliiii \\ ii 1 1 i -i-ii.. 

 """' In'i|in nlly |uilili.-li-il in ilu- I'.S. AIIII-I. Id |i.n iiiinii 



bulletins, in tin- l,u!Ic-iin> t'i.,m r\|n-i in,, ni ,1 : .1,1) 111 tlir horticull 



journ 



MM.iir :LII<| !'.! rlow give it as o iirii on every A ' 



i 



