254 On Forms of the Hop 



inoculation from adjacent mildewed seedlings, most of which were 

 affected to the severest extent. In every case, each of these five seedlings 

 had mildewed plants on either side of it. 



The following inoculation experiment was carried out on the seedling 

 Z 25 in 1918. On June 10th several lateral shoots, 9 in. to 1 ft. long, 

 produced from the main stem at about 5 ft. from the ground, were 

 inoculated by "atomising" three leaves on each shoot with water 

 containing conidia of S. Hnmidi. The seedlings Z 24 and Z 26 were 

 of the same age and parentage as Z 25, and had proved in 1917 to be 

 very susceptible (S^). On June 30th the following results were noted: 



At this date the patches of mildew were small, but many were densely 

 powdery with conidia. The infected leaves v/ere picked off to prevent 

 the spread of the mildew to the commercial part of the hop-garden. 



The evidence would seem to show that these five seedlings of Group 2 

 (which are all 5-year-old flowering plants) remain immune to mildew, 

 after being grown for four years in a hop-garden under ordinary con- 

 ditions of cultivation and manuring; although under the same conditions 

 a large number of seedlings of the same age and parentage have proved 

 each season to be exceedingly susceptible. 



Grouj) 3. 9 seedlings (10 to 18). 



Plant 10. Ref. No. OR 38 $ 



1914 G (I), 



1916 H(Si), 



1917 H (8-); o -cuts" 1916/J7 G(l*), 



1918 \ 3 cuts 191()/17, now 2 cuts 1910/17 G (1) 9 cuts 1917, 18 G (1), 

 ill H; Rcf. No. W.5(3(S-), 

 „ Y28(,S^'), 

 ,, Z4(S^'). 

 * iSce footnote 1, next page. 



As a 2-year-old seedling OR 38 was persistently immune in the green- 

 house ((1), p. 45G), in 1914; that winter it was planted out in the hop- 

 garden. It flowered there in 1916, and in October of that year it proved 



