FUNGOID PESTS OF CULTIVATED PLANTS, 119 



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 

 are contained in asci. 



It seems rather doubtful whether the "chancre" attributed to 

 Spharopsis Malorum (Bull, de la Soc. Myc. de France, 1903, p. 134) may 

 not be a condition, or stage, in the development of this same disease. 

 (Fig. 15.) 



At present this is a rare disease, and must be hunted after to be 

 discovered ; but it is quite possible for it to become a pest if it establishes 

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

 troublesome, and consequently no experiments have been made for its 

 eradication. 



We should certainly recommend its destruction wherever found, since 

 it is quite capable of extending itself both by its mycelium and sporules. 



Sacc. Syll. in. 2121 ; Cooke Hdbk. No. 1254. 



There is a small twig pustule, caused by Phoma Mali, which is not so 

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

 sporules (8 //, long) are expelled when mature, and in some places it is 

 looked upon with suspicion. 



APPLE-TREE CANKER. 

 Nectria ditissima (Tul.), PI. X. fig. 6. 



Ten or twelve years since E. Goethe propounded the opinion that canker 

 on Apple trees was produced by the growth of the above-named fungus, 

 which is of the Sphceria kind, a little resembling those clusters of red 

 Nectria which are so common on Currant twigs, but smaller. Goethe 

 claims to have demonstrated his position by cultivating the parasite both 

 from conidia and ascospores. The same fungus he contends produces 

 canker on various kinds of Pear trees, and the sporidia of the Nectria 

 from the Apple were found to produce canker on the Beech and Sycamore, 

 and again from these trees on the Apple. 



According to Hartig the fungus enters through wounds caused by 

 hail or the puncture of an insect. The best remedy, according to these 

 authorities, is to cut out the diseased tissues and anoint carefully with ccal 

 tar. 



The fungus consists of a number of little red dots, scarcely so large as 

 a pin's head, growing in clusters in cracks of the bark. These minute 

 dots are spherical and smooth, seated on a white mycelium, and when 

 mature enclosing a kind of pulpy nucleus, like a tiny drop of gelatin, and 

 which consists of a great number of long cylindrical tubes, or asci, each 

 enclosing a row of eight elliptical sporidia, which are divided by a trans- 

 verse septum into two cells. When ripe they are capable of germination 

 from each cell (14 x5-6/w). 



Occurs in France and Germany. 



Gard. Chron. March 8 and April 19, 1884, p. 313 ; 1891, p. 300, figs. 

 66, 67 ; -Sacc. Syll. ii. 4671 ; Mass. PL Dis. 127, fig. 24 ; Grevillea, ix. 

 p. 116 ; Tubeuf, Dis. p. 187, figs. 



