E. S. Salmon 153 



of the same year when the plant was examined minutely all over, no 

 trace of mildew could be found on leaves or hops, although some of the 

 lateral shoots of Z 26, bearing mildewed hops, had twined round the 

 stems of Z 25. In 1920, on August 28, Z 25 was free from mildew; when 

 examined in October there was no mildew on the leaves, but a trace of 

 mildew occurred on the hops, particularly at the tips. In 1920 both 

 Z 24 and Z 26 were so severely infested with mildew that all their hops 

 were destroyed. 



Ref. no. Z 31. So far as this seedling has been able to be tested in 

 the open, it shows susceptibility to the extent of S^. 



Ref. no. Z 42. In the two years, 1917 and 1918, when this seedling 

 could be tested, it remained free from mildew, while Z 41 on one side 

 was S^, and Z 43 on the other side was S^. 



Ref. no. OA 34. In 1917 and 1918 the amount of mildew present (on 

 the hops) was recorded as S^; in 1919 and 1920 there was only a mere 

 trace of mildew (also on the hops). The neighbouring plant OA 35 was 

 recorded as S^ each year, and in 1918, 1919 and 1920 was so severely 

 attacked by mildew that the crop was destroyed. 



Ref. no. OA 49. This seedling remained free from mildew in 1917, 

 1918 and 1919; in 1920 there was a mere trace of mildew on a few hops 

 in an otherwise completely healthy crop. In 1919 a cutting was grown 

 in the greenhouse and proved immune ; on July 5 this cutting was taken 

 out of the greenhouse and placed in the open air. The plant produced a 

 fresh shoot, which by September 30 was 1 ft. 8 in. high; round this shoot 

 the stem of another hop-seedHng which bore mildewed leaves had twined, 

 but OA 49 remained immune. 



Ref. no. OB 26. No opportunity has yet occurred of testing this 

 seedling in the open. 



Ref. no. OB 34. The only time that mildew has occurred on this 

 seedUng was in October 1918, and then only one "hop" was found in- 

 fected. This single hop-cone had been attacked when in an early stage 

 of development and had been converted into a knob-like growth (white 

 and powdery with the conidial stage of the mildew). This mildewed 

 " hop " occurred in the midst of a normal crop of healthy hops. 



Ref. no. OD 19. This seedling remained free from mildew in 1917 

 and 1918, notwithstanding the fact that in both seasons OD 18 was 

 mildewed to the extent of S^, the crop being destroyed by mildew in 

 1918. In 1918 a strong lateral shoot of OD 19 climbed round the stem 

 of OD 18 and produced there perfectly healthy hops among the exces- 

 sively mildewed hops of OD 18. In 1919 OD 19 showed a trace of 



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