186 On Diseases of Plum Trees 



B. Prince of Wales. 



(5) One mature tree was dead, two or three others were dying 

 back from the top. All diseased trees were found at Histon, Cam- 

 bridgeshire. Small, blue-green, sunken pycnidia were borne singly on 

 poorly-developed stromata, erumpent on keeping (Fig. 4). Pink 

 tendrils of the usual type were developed in a moist chamber. 



C. Pond's Seedling. 



(6) A mature tree at Long Sutton near Wisbech, one side of which 

 was dying. The disease had spread from above downwards. Pycnidia 

 were borne in groups on sunken, whitish, poorly-developed stromata. 

 There were pink tendrils of spores, the dimensions of which were 5 jx 

 by 1 /x. At the time Mr Brooks obtained this material the foliage of 

 the parts of the tree affected was wilted and brown, presenting a scorched 

 appearance. 



(7) Piece of branch about 4 ins. in diameter from a tree at Long 

 Sutton. Pycnidia and spores as in (6) above, but stromata erumpent, 

 and dark- coloured. 



It is possible broadly to divide the above into: 



(a) Those with stromata well developed, dark coloured, and 

 erumpent — Victoria (2) and (3) and Pond's Seedling (7). 



(b) Those with stromata poorly developed, light coloured, and 

 sunken — Victoria (1) and Pond's Seedling (6). 



Too much stress, however, cannot be placed on this classification, 

 in view of the great similarity of the spores and tendrils (except in the 

 case of Victoria (3) where the dark-red tendrils and white crust point 

 to a wider divergence) and also, as will be seen later, on account of the 

 marked influence of media on pycnidial development. 



The presence of a stroma more or less deeply seated in the baik, 

 and sharply delimited from the surrounding tissues, indicates that all 

 the fungi belong to the sub-genus Leucostoma of the genus Valsa, 

 assuming, as is highly probable, that the stroma of the perithecial 

 stage is similar to that bearing pycnidia. Beyond this it is not pos- 

 sible to go. The chief distinction from Eutypella prunastri appears to 

 be in the production of well-marked tendrils of spores (cf. Massee, I.e.). 



