FUNGOID PESTS 



production. In the case of young trees frequent spraying with dilute Bor- 

 deaux mixture may be a preventive. 



Plum-tree Mildew, Podosphcera tridactyla, attacks the foliage of Plum 

 and Cherry trees, and resembles the Gooseberry Mildew in appearance. The 

 receptacles in the case of the Plum have usually six or seven radiating arms, 

 while those of the Cherry have from eighteen to twenty of these appendages. 

 The disease may be checked by the application of sulphur. 



Plum Pockets, Eccoascus Pruni, is a disease easily recognised by reason 

 of the familiar " Bladder Plums " which are the result of the attack. These 

 galled and swollen fruits, as well as Witches' Brooms, are frequently found 

 on the Bullace, the fungus being known as Exoascus insititice. In the case 

 of this tree the diseased fruits may attain dimensions three or four times 

 larger than that of a normal-sized fruit. The mycelium is perennial in the 

 twigs, and from these travels to the ovaries of the flowers, taking possession 

 of the young fruit, diverting and absorbing the supplies of nutriment, pre- 

 venting the formation of seed, and causing considerable malformation of the 

 fruit. Growing from the mycelium are closely-packed cylindrical asci, each 

 containing eight sporidia, which, escaping from the infected fruit, may carry 

 on the disease. The diseased fruits, after going through various changes of 

 colour, become shrivelled, and fall to the ground. All " pockets " should be 

 collected and burned, and the branches may with advantage be cut back 

 beyond the point of infection. 



Witches' Broom of Cherry is caused by the fungus Exoascus Cents/. The 

 disease shows itself in the production of dense tufts of branches, growing 

 apparently from a central point, very similar to those already described in 

 the chapter on Galls, under the title of " Witch Knots." In the present 

 case the fungus appears as a hoary bloom on the branches. The slender, 

 club-shaped asci enclose nearly globose sporidia. The only known remedy 

 is to cut out the disease tufts and burn them, so as to prevent propagation 

 by spores. 



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