68 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



2. CONTROL OF DISEASE BY PLANTING AND CULTIVATION. 



I must refer only very briefly to this part of the subject. 



The site of fruit plantations should be carefully chosen with 

 reference to the control of disease. Exposure to early or late frosts, 

 or to excessive moisture, will encourage disease. Proximity to 

 woodlands may bring on very bad attacks of caterpillar. 



Over-crowding must be avoided. Good ventilation is as good as 

 a good spraying. Gooseberry bushes, e.g., must not be planted so 

 close together that there is no room to walk round them to spray them 

 against American Gooseberry-mildew. 



Excessive nitrogenous manuring should be avoided. 



3. CONTROL OF DISEASE BY DIRECT METHODS OTHER THAN 

 SPRAYING. 



This method of dealing with disease is far too often neglected, and 

 I want to drive home this point with what emphasis I can. 



Too many fruit-growers are inclined to rely entirely on spraying ; 

 whereas, good as spraying is against many insect and fungus diseases, 

 it must be remembered that it is entirely useless against some of the 

 worst pests. 



I will cite instances of some fungus and insect diseases of this class : 

 "Silver-leaf" of Victoria (and other) Plum-trees. — This disease is 

 caused by the fungus Stereum purpureum, which comes to the surface 

 of the stem (or branch) when the tree (or branch) is dead, and forms 

 there myriads of its spores, which spread the disease to surrounding 

 Plum-trees. Every tree killed by Silver-leaf and allowed to remain 

 in the garden or plantation is a most prolific source of infection. We 

 could prevent Silver-leaf if an order could be carried out for the grubbing 

 up and burning of " silvered " trees. 



Many a fruit-grower has remarked to me — "No cure known for 

 ' Silver-leaf,' I suppose ? " — and continues to leave the dead trees to 

 propagate the disease. Well — perhaps, a Joint Committee of the 

 R.H.S. and the Chamber of Horticulture will one day deal with such 

 offenders ! 



Apple " canker " is in the same class ; spraying is of no use, and 

 the knife is the remedy in cutting out the cankers : or, in really bad 

 cases, top-grafting with strong-growing canker-resistant varieties — 

 such as ' Bramley's Seedling ' or ' Newton Wonder ' — must be em- 

 ployed. 



I should like to refer here to the ' Brown Rot ' canker which has 

 attacked recently the variety ' Lord Derby ' with such virulence. 

 Through the very thorough work of Mr. H. Wormald, my assistant 

 at Wye College, we know now that a particular strain of the " Brown 

 Rot " fungus (Monilia cinerea) is responsible for the blossom wilt 

 and canker of ' Lord Derby ' and of a few other varieties of apples. 

 Cutting off the wilted blossom spurs as soon as attacked, and cutting 



