10 July, 1917.] Anthracnose or Black Spot of the Vine. 413 



appearance of the disease. So far as climate is concerned, there is 

 little difference between the three localities. In the new settlements 

 there were evidently not enough starting points for the fungus to make 

 an early appearance. In this respect Black Spot differs radically from 

 Downy Mildew and Oidium ; one vine affected with either of these 

 diseases early in the season would suffice for the invasion of a whole 

 district, but not so with Black Spot. 





c^ 



Fig. 10. 



Completely formed sclerotium, 

 highly magnified. Dark-brown outer 

 cells above, central cells smaller and 

 paler. Beneath is damaged tissue 

 containing non-condensed mycelium. 

 After Gouirand and Bergeron. 



Fig. 11. 



Sprouting of a sclerotium in spring. 

 The surface cells are bcgimiing to 

 .send out spore-bearing shoots B. 

 After Gouirand and Bergeron. 



Let us beware of placing too much reliance on this slow spread. 

 After the outbreak last year, scars are to be found even in new districts 

 where the disease was practically uuknown then, and these are suffi- 

 ciently numerous to permit of widespread infection should climatic con- 

 ditions favour fungus growth. In all vineyards which suffered last 

 year the number of scars, all oi which contain the fungus in a dormant 

 state, is simply enormous. The preventive treatment shortly to be 

 described cannot therefore be too strongly recommended 

 it would be to court disaster. 



To neglect 



IIlBEKNATING FORMS ScLEROTIA. 



A sclerotium* is a resting stage formed by many different fungi. 

 The curious formation sometimes ploughed up on new ground under the 



name of " native bread " is nothing 

 else than a large sclerotium of a 

 fungus known botanically as Polij- 

 ponis mi/tilla, C. & M. The 

 sclerotia. of Manginia ampelina are 

 similar in structure, though of far 

 smaller size, being almost micro- 

 scopic. This resting or wintering 

 form of the fungus was mentioned 

 by Goethe in 1878, also by Viala 

 and Ravaz (C.R. 18/6/88.) It is 

 dealt with at some length by 

 2/1/97), whose investigations throw 

 considerable light on the action of the acid iron sulphate preventive 

 treatment, whicE practical experience had shown to be effectual long 



"A 



Fig. 12. 



Spore production by shoots, the 

 first stages of which are shown in 

 Fig. 11. After Gouirand and Ber- 

 geron. 



Gouirand and Bergeron (R. Vit. 



• The following definition is given by De Bary : — " Pluricelular Tuber-like Reservoir of reserved 

 material, forming on a primary filamentous myceliurii, from which it becomes detached when its develop- 

 ment is complete, usually remains dormant for a time, and ultimately produces shoots which develop 

 into Sporophores at the expense of the reserve material," (Comparative Morphology and Biology of the 

 Fungi, Mycctozoa, and Bacteria, p. 499.) 



