29(3 On Foi^ms of the Hop resistant to Mildew 



immune to mildew both in the greenhouse and when grown in the open 

 in a manured hop-garden. During 1918 and 1919, 47 potted plants (from 

 the two sources noted above) were grown in the greenhouse and re- 

 peatedly inoculated with eoniditt throughout the growing season: no 

 trace of any infection resulted. The plants ("hills") in the hop-garden, 

 of which nine were obtained from Messrs Bunyard and three from 

 Messrs Bide, have all remained immune to mildew for the past three to 

 seven years. 



This immune female Golden Hop lacks sufficient vigour of growth 

 (due possibly to its possession of yellow, instead of green, leaves) to 

 make it probable that it will ever be suitable as a commercial variety 

 for hop-growers. With the object of trying to obtain a suitable green- 

 leaved hop immune to mildew, "seed" was collected and sown in 1917 

 from a plant of the immune "Golden Hop"' growing in the hop-garden 

 at Wye College (obtained originally from Messrs Bunyard) — the male 

 parent being unknown. In 1918 a counting of the seedlings in the three 

 seed-boxes was made according to the colour of the first leaves, with 

 the following results: 



170 178 



" Yellow " included several different shades of yellow : among " green " 

 were various shades, including pale-green, but not yellowish-green. 



The most vigorous of the above seedlings were planted out in the 

 hop-garden in the winter of 1918-19, and during 1919 it could be 

 observed that some seedlings were green-leaved (sometimes dark green) 

 and some yellow (or "golden") leaved. 



Other seedlings of the same origin were tested for susceptibility to 

 mildew. These consisted of 68 seedlings raised from one plant of the 

 Golden Hop (obtained originally from Messrs Bunyard) and 37 seedlings 

 from another y)lant of the same origin. These seedlings were 2-year-old 

 plants, non-flowering, in pots, and were kept during 1919 in the green- 

 house and constantly subjected to inoculation by conidia throughout the 

 season. Their behaviour towards the mildew was as follows: 



Seedlings of plant 1 . . . 



(Hcf. no. 1/17) 

 Seedling's of plant 2 ... 



(R<^f. IK.. 317) 



