M. A. Bailey 163 



bush. The more heavily infected bushes showed mildew on the young 

 shoots, and an examination of these shoots made at a subsequent date 

 showed perithecia present amongst the mycelium, but the condition 

 of the ascospores in these perithecia was not ascertained. 



When the examination of the bushes had been completed, they 

 were sprayed with Liver of Sulphur with the idea of keeping the disease 

 under control, though this wash has since been proved by Professor 

 Salmon to have little or no effect in the case of this particular mildew. 



On November 6th all the bushes were transplanted to another 

 plot (Plot D) situated about 50 yards from Plot A and separated from 

 it by a low hedge. As it was desired to make observations on the 

 natural habit of growth of these seedlings, they were allowed to remain 

 entirely unpruned. 



The following year (1913) a new batch of seedlings was pricked 

 out during June on a portion of Plot A, which had been occupied by 

 the infected seedlings of the previous year. 



The summer of 1913 appeared to be unfavourable to the growth of 

 the mildew, and a relatively slight, though more or less general, infection 

 was recorded on the seedlings of Plot A. The season was a very dry 

 one, and this probably had some effect, if only through the more rapid 

 ripening of the young wood. The plants in Plot D, many of which, as 

 recorded above, had been heavily infected during the previous year, 

 remained entirely free from mildew, with the exception of one or two 

 bushes — less than 0-5 % — which showed very slight traces of disease. 



During the winter the plants received rather light pruning. 



In May, 1914, the remaining portion of Plot A was filled up with 

 newly raised seedlings, those of the previous year being allowed to 

 remain in their places. 



Mildew reappeared during the summer in Plot A, and in August 

 it was found that almost every one of the one-year-old plants was 

 more or less heavily infected, as also were all those of the current year, 

 which had made sufficient growth. As in the previous year, the plants 

 in Plot D remained practically free from mildew, despite the fact that 

 they made a lot of young growth, of the kind which is looked upon as 

 being specially susceptible to attack. 



To account for the apparent lack of infection during the summers 

 of 1913 and 1914 of the plants in Plot D by oidia from the infected 

 plants in Plot A, I can only suggest that the presence of the low hedge 

 between the two plots coupled with the fact that Plot D lies more or 

 less to windward of Plot A (D lies south of A and the prevalent wind 



11—2 



