Stone Fruits: Plums 117 



fined to one spot (the experience gained at which could never be held 

 to apply to the whole kingdom), would be brought under the eyes of 

 growers, who would take more interest in them and learn more from 

 them than they would from what is done at an experimental farm which 

 many of them would never be able to visit, and the literature of which 

 they might never read; finally, the saving of expense. 



As things are, the grower must make what experiments he can. He 

 will find, as has been said, the use of lime, sulphate of iron, and also 

 sulphate of potash useful. The disease is said to be highly contagious, 

 able to transfer itself from tree to tree by means of spores carried on 

 the wind when liberated from the decaying wood it has killed. To make 

 sure, all wood cut from affected trees should be quickly burned, and the 

 saw or knife, after cutting on an affected tree, should be dipped in some 

 antiseptic fluid before being used on another tree. When a tree is badly 

 diseased the only thing known at present to do is to root it up. Before 

 planting another, the hole should be broken up deeply and 3 Ib. of 

 sulphate of iron sown over it, and a day or so after 15 Ib. freshly slaked 

 lime. [w. G. L.] 



This disease, Silver Leaf, is much in evidence at the present day, 

 both at home and in countries as far distant as New Zealand. The 

 symptoms are a change from the normal green colour of the leaves to 

 a dull lead or silvery tint. During the first season of attack usually 

 only a few branches here and there show the disease; the second year, 

 as a rule, all the leaves on the tree are attacked, and very frequently 

 during the third year the tree dies outright. It is believed by some 

 that this disease is caused by a fungus called Stereum purpureum, and 

 the evidence in support of this belief appears to be so convincing that 

 it has to be admitted that the fungus can cause Silver Leaf. On the 

 other hand, it is more than doubtful as to whether the enormous increase 

 of the disease during recent years in many parts of the world is all due 

 to Stereum purpureum, a very common fungus in this country. Why 

 has this fungus only recently attacked Plum trees? 



Apart from this question, however, it is important to remember that 

 when a tree is once attacked, as a rule it does not recover, and should 

 be replaced at once by another tree, which does not become diseased 

 through occupying the place of the diseased tree. Not more than a 

 dozen cases are on record where a diseased tree has recovered out of 

 the thousands that have been attacked. 



No cure is known. As a preventive measure all Stereum purpureum, 

 a fungus forming purplish or lilac crusts on dead branches, should be 

 removed and burned. When old, the fungus becomes bleached and almost 

 white. 



Crown Gall. Described under " Loganberry ". (See p. 163.) 



Gumming-, See p. 52. [G. M.] 



