238 THE FRUIT GROWER'S GUIDE. 



A diseased tree must not be admitted. Wild Cherries, Bullaces, Sloe-bushes, and above all 

 common Laurel, should not have places near stone-fruit trees. Acacias, also, are parents 

 of gum disease, but it does not exist on trees subject to canker, Elms excepted. In the 

 Elm the morbid product is excessive, often saturating the soil a considerable distance 

 from the stem. The deposit shines like varnish, and is a compound of ulmin and 

 carbonate of potash, The white matter around the wound Vauquelin found Avas 

 composed of vegetable matter, GO'5 ; carbonate of potash, 34'2 ; carbonate of lime, 

 5 '0 ; carbonate of magnesia, 0*3 = 100 -0. The morbid product has a close connection 

 with sugar, and hence the value of gum as a dietary. Cherry is the best of British- 

 grown gums. 



Apple Scab. Apple and pear trees are often afflicted with a disease that causes un- 

 sightly blotches on their fruit, and disfigures the leaves and young shoots. The scabs 

 generally appear on the exposed side of the fruit, and this, in consequence, is always 

 less developed than the other. Certain varieties of apples are more subject to scab than 

 others, particularly the thin-skinned and tender-fleshed, such as Hawthornden, Stirling 

 Castle, Yorkshire Beauty, Kymer, and Dumelow's Seedling. Eussets generally escape, 

 but sorts with semi-russety skins sometimes become deformed. Immunity from this 

 disease is most decided in kinds having greasy, elastic coats, such as Lord Grosvenor, 

 Manks Codlin, Ecklinville, Nelson Codlin, Golden Noble, Lane's Prince Albert, 

 Bramley's Seedling and others, yet no varieties are in all conditions of soil, climate, and 

 culture scab proof. Season greatly influences the prevalence and development of scab. 

 It flourishes in a wet season, damp localities, and in gardens and orchards lacking health 

 essentials ; but it appears also in a dry year. Healthy conditions of cultivation always 

 render an attack less severe and more amenable to the effects of remedial measures. 



Scab growths are due to a fungus Cladosporium dendriticum. On the fruit it gives 

 rise to black patches, which in bad cases run together, covering a large part of the 

 surface, and occasion its cracking by the contraction of the skin and subsequent attempts 

 at swelling. Thus the fruit is greatly disfigured, often to the extent of rendering it 

 worthless, always decreasing its using and marketing value. The general appearance 

 of fruit affected with scab is well shown in the engraving on the next page. 



The black small spot soon becomes an irregularly rounded patch, depressed and 

 black in the centre, enclosed by a small white ring, outside which is a black border, 

 indicating the growth of the fungus. The white ring is the edge of the skin of the 

 fruit, and the depressed dark spot is occupied with a mass of minute bodies, which 



