258 Transactions British Mycological Society. 



Excision of cankered areas is undoubtedly profitable in some 

 cases, particularly in young trees, as this trouble, like most 

 others, becomes cumulative if neglected. 



Care must be taken to prevent the development of dangerous 

 fungi not only within the plantation but also in its immediate 

 vicinity. On more than one occasion I have seen silvered sloe 

 trees with the fungus Stereum purpureum developing on the 

 dying branches, in hedges bordering plum plantations. It is 

 obvious that such trees should be removed, as well as an}^ other, 

 such as laburnum, which happen to develop silver-leaf disease. 

 The stumps of elm trees in hedgerows are a prolific source of 

 the same species of Stereum and it is known that the fungus 

 from this source is just as dangerous in causing silver-leaf as is 

 Stereum taken from a dying ' Victoria ' plum. Stumps of practi- 

 cally all broad-leaved trees with the exception of oak are liable 

 to give rise to profuse growths of this fungus. Such stumps 

 should be eradicated, charred, or covered with soil if they are 

 on the borders of fruit plantations. Fruit gardens situated in 

 the midst of agricultural land are more favourably placed as 

 regards danger of attack by wound parasites than are plantations 

 near woods, in which most of these fungi find an excellent 

 harbourage. There is no excuse, however, for such a practice 

 as that of making fences of plum wood around fruit plantations. 

 That is simply asking for trouble. I once saw a fence, made of 

 plum wood, separating one plum plantation from another, 

 which was literally covered with the fructification of Stereum 

 purpureum. Can it be wondered at that silver-leaf disease was 

 rife in both these gardens? In another place, a number of half- 

 standard plums were tied up to stakes made of birch stems on 

 which Stereum was developing in abundance. 



With a few diseases such as plum rust and black currant rust, 

 the fungus completes its life on two different kinds of plants. 

 Thus in the plum rust, the fungus lives indefinitely in the 

 perennial parts of the commonly cultivated Anemone, Anemone 

 coronaria, in the leaves of which spores are produced in the 

 spring, which in turn affect plum leaves. Unless, therefore, the 

 diseased anemones are eradicated, there is no means of pre- 

 venting attacks of plum rust in the immediate vicinity. Some 

 years ago, I saw a very severe attack of plum rust in fruit 

 orchards near a florist's garden in which diseased anemones 

 were known to be present. So severe was the plum rust that 

 the trees were defoliated by the end of August. More recently, 

 the florist's garden has been converted to other purposes and 

 plum rust has been scarcely noticeable in the \dcinity. One is 

 strongly inclined to suggest cause and effect as operating here. 

 With black currant rust, in which the effect of a bad attack is 



