164 Note on American Gooseberry Mildew 



is S.W.) has been sufficient to prevent the transportation by wind of all 

 but a relatively few spores. 



Mr Rogers, in a note in the January number of this Journal, refers 

 to a case in which all the visibly affected wood of diseased bushes was 

 removed, and the bushes transplanted to uninfected ground, with the 

 result that they were free from disease in the following year. In view 

 of the occurrences described above, it seems difficult to resist the con- 

 clusion that it was the transplantation and not the pruning which was 

 the important factor in the recovery of these bushes, and it is even 

 possible that they might have remained free if the pruning had been 

 omitted. 



Salmon has recorded 1 that if shoots bearing the winter stage of the 

 mildew are removed at the beginning of August and gently tapped 

 over a piece of paper, dozens of perithecia, ripe and in excellent condition, 

 fall from the mycelium. 



The above observations tend to confirm his view that the majority 

 of the perithecia fall from the meshes of the mycelium in the late summer 

 and autumn, and that of those which remain throughout the winter 

 very few are viable. 



On the other hand, Salmon, in a paper read at the meeting of the 

 Association of Economic Biologists, 1914, refers to the frequency with 

 which the disease reappears first on young berries on the upper branches, 

 and to account for this he suggests that in these cases the reinfection 

 has originated from perithecia which had lodged in crevices in the 

 bark or between bud scales, etc. Though, in my experiments, the first 

 raised seedling gooseberries were only about nine months old when 

 moved to their new quarters, the majority had already made consider- 

 able growth. In many cases the bark had begun to show longitudinal 

 cracks or even slight flaking, and the plants were, of course, plentifully 

 supplied with bud scales. Also, if the primary reinfection originates 

 from perithecia entangled in this manner, it does not seem clear why 

 the lower branches should not be affected to an equal degree. 



It will be seen above that in the case of the first batch of seedlings 

 raised there was a tendency for the mildew to appear more particularly 

 on leaves high up on the bushes, and it seems possible that the explana- 

 tion of this and of the case described by Mr Salmon may lie in the 

 different atmospheric conditions which obtain at the top and at the 

 bottom of a bush, when its leaves are sufficiently developed. Spore3 

 which alight near the top of a bush must be subjected to greater ranges 

 1 -Journal of Agr. ScL, vol. vi. p. 2, May. 1914. 



