FUNGI 239 



occasionally dipping it into a solution of carbolic acid, or some 

 such disinfectant. 



Inoculations were attempted with the pulp from silvered leaves, 

 but in no case was the disease communicated in this way. It 

 was also sought to ascertain whether the scion or bud from an 

 infected tree could communicate the disease to a sound stock, 

 but no evidence of this was obtained, for such scion or bud never 

 effected a junction with the stock. In the same way it was 

 found impossible to graft sound scions on to affected stocks. 



Evidence that the disease was not communicated from tree 

 to tree underground was obtained, as in the case previously 

 mentioned, by growing a row of diseased trees two feet away 

 from a row of sound ones, and aggravating matters by digging 

 roughly between them, so as to injure the roots. But in no case 

 did the sound trees develop the disease. The fact that plum 

 trees may often be silvered in the leaves of the branches, without 

 there being any signs of silvering in those on the suckers arising 

 from the roots, is a further proof that the disease does not 

 originate in the roots. 



Evidence collected both in this country and abroad failed to 

 connect silver-leaf with any special character or condition of the 

 soil in which the trees are growing. 



The general conclusion from the Woburn experiments was 

 that silver-leaf is a disease which is communicated solely by the 

 entrance of the fungus spores through a wound on the trees, and 

 can be combated solely by reducing the chances of such an entry. 

 To do this it is necessary, in the first place, to diminish the pro- 

 duction of fungus spores ; every tree which is badly attacked by 

 the disease, and certainly every affected tree which contains 

 any dead wood, should be rooted out, and promptly burnt. 

 Inasmuch as recovery is possible, it may be advisable in some 

 cases to leave a tree which has been attacked, to give it a chance 

 of recovery, but that certainly should not be done if the attack 

 is a severe one ; and, where only one or two trees are affected, 

 their immediate removal, whether they are badly attacked or 

 not, would be by far the wisest course. Where removal is not 

 carried out, the affected branches at least should be cut off, 

 and cut off well below the point at which silvering has started. 

 In the second place, everything possible should be done to 

 prevent wounds being left open in any plantation where silver- 

 leaf exists ; any broken surfaces should be trimmed, and covered 

 with a coating of tar, and the wounds caused in pruning should 

 likewise be tarred. It is very noticeable that an attack of silver- 



