256 Transactions British Mycological Society. 



branches are allowed to remain in the plantation, the fungus 

 which killed them will soon fructify and shed its spores around 

 in the same way as if still attached to the standing tree. Large 

 wood piles are often seen in fruit plantations forming excellent 

 breeding grounds for such a destructive pest as Stereum pur- 

 pur eiim. In these days of fuel shortage there should be no 

 difficulty in disposing of wood cut out in this way. Not long 

 ago I saw a gigantic pile of red currant prunings in the midst of 

 a large area of red currants, the prunings being literally smothered 

 with the pink fructifications of Nectria cinnabarina , which, as 

 many fruit growers know to their cost, is becoming increasingly 

 destructive to red currants. There is no reason why these 

 prunings should not have been burnt as soon as collected. In 

 cutting out diseased branches, action must be sufficiently drastic 

 to ensure that the downward limit reached by the fungus is 

 excised. This is particularly important with silver-leaf disease, 

 the region penetrated by the fungus being marked by a brown 

 discolouration in the wood, which is often a considerable 

 distance below the silvered foliage. In this connection mention 

 may be made of a case seen during the summer : the branches of 

 certain silvered ' Lord Grosvenor ' apple trees had been cut back, 

 but not far enough, as the fungus Stereum purpureuryi was 

 developing in quantity from each of the exposed extremities. 

 We have not infrequently seen silvered trees the upper parts 

 of which have been lopped and the trunks left standing and 

 bearing enormous quantities of Stereum. Such a practice cannot 

 be too strongly condemned. Where large branches are severed, 

 the exposed surfaces should be made smooth and covered with 

 tar to prevent the ingress of wound parasites. While on the 

 subject of branch infection by silver-leaf, it may be mentioned 

 that it is usually the wisest economy to cut out silvered branches 

 as they appear, i.e. before they die back; there is then not the 

 slightest opportunity of the fungus fructifying through delay 

 in cutting out the dead wood. 



With other diseases there is often no means of telling that a 

 parasite has entered the tree until the branches begin to die 

 back and fructifications of the fungus appear. This is particu- 

 larly the case with the die-back of plums and cherries caused 

 by the fungus Cytospora leucostoma and the affection of plums 

 due to Fames pomaceus. In such, drastic action can only be 

 taken upon the appearance of the first external signs of disease, 

 when the greater part of the trees can often be saved, if excision 

 is effected judiciously. \Miile dealing with the subject of ex- 

 cision, it is recommended that, in soft-wooded varieties such as 

 the ' Victoria ' plum, the branches of which frequently break 

 through overcropping, broken limbs should be cut back flush 



