10 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Apple-twig Tumour. 

 Botryodiplodia pyrcnophora (Sacc), PI. X. fig. 5. 



Little swellings are sometimes to be seen on Apple tw r igs in which the 

 bark cracks in an irregular manner and exhibits beneath a cluster of black 

 perithecia, about the size of pins' heads, closely packed together, and 

 seated upon a kind of cushion formed from the mycelium. 



These perithecia when mature contain a mass of rather large elliptical 

 sporules, at first one-celled and colourless, but afterwards divided across 

 the centre into two cells, and then of a deep brown colour. Possibly this 

 is only a condition of a more highly organised fungus in which the spores 

 arc contained in asci. 



Fig. 4 Bp&BBOPSXS malokuu. 



It Beems rather doubtful whether the "chancre" attributed to 

 SpharopstS malo rum (Bull, de la Soc. Myc. de France, 1903, p. 134) may 

 in t be a condition, or stage, in the development cf this same disease . 

 (Pig. 1.) 



At jn< >cm this is a rare disease, and must be hunted after to be 

 di>co\tre<l ; but it is quite possible for it to become a pest if it establishes 

 itx lf in an orchard. Hitherto we have no record of its having become 

 troublesome, and consequently no experiments have been made [or its 

 eradication. 



\\ i diould certainly recommend its destruction wherever found, since 

 it i> quite capable of extending itself hold by its mycelium and sporules. 

 Sit,, . Syll. iii. 2121 ; Cooke lldhk. No. 1201. 



Then- is a small twig pustule, caused by Phoma mali, which is not so 

 elustared or conspicuous on the twigs of Apple and Pear trees. The 



