DISEASES OF THE APPLE TREE ] 277 



A common fungus on our apple trees is Sphaero- 

 theca Castagnei Lev. which attacks the growing twigs as 

 a floury or mouldy production covering the leaves, the 

 leaf-stalks and the twigs (apple-mildew), and deforms 

 the foliage, weakens the twig, and prevents or interferes 

 with the formation of flower-buds. A good remedy against 

 this disease when prevalent is to apply one or two 

 dustings with flowers of sulphur on a dewy morning. 



Four species of Polyporus, viz : P. spumeus Fr., 

 P. civnamomeus Trog., P. ignarius Fr., and P. hispidus 

 Fr., and also Hydnum Schiedermayri Henfl. have been 

 noted on the apple tree in continental orchards. Of 

 these only P. hispidus has been observed on rare occa- 

 sions on our apple trees. 



Rhizoctonia UatiD.C. is sometimes troublesome on 

 the roots of apple trees growing in moist situations, and 

 if the mycelium extends to the main roots the tree will 

 probably succumb. The mycelium is at first white and 

 becomes brown or violet-brown with age, and after 

 killiiig the tissues of the minor roots extends upwards to 

 the larger roots. The tree shows signs of the disease 

 by a weak and chlorotic appearance, the leaves com- 

 mencing to dry off at the tips early in summer and are 

 shed long before autumn. The dead or dying roots 

 should be carefully dug up and burned, and those showing 

 signs of infection should be cut back to the healthy tissue 

 and the wound protected from re-infection by painting 

 over with tar. However, this disease is more frequent 

 on the loquat than on the apple. 



The misletoe (Viscum album L) is a frequent 

 parasite of the apple all over the continent as well as in 

 England but does not exist in these Islands, and it is 

 questionable whether it can thrive here at all, .as repeated 

 attempts to inoculate apple-trees with the seeds of the 

 parasite for the sake of ornament always gave negative 

 results. 



