TOMATO BLACK SPOT 267 



Tomato by top dressing with soil, sometimes effective in en- 

 abling plant to mature fruit : d y roots and root-stem destroyed 

 by Sleeping Disease to ground level ; e, top dressing of soil 

 encouraged rooting from aerial part of stem ; f, ground level. 

 C, transverse (across stem) section of drooping plant (A) just 

 above ground, natural size : g, vertical tissues apparently 

 healthy ; /;, woody fibres brown and diseased ; /, pith cells, 

 quite normal. D, section of stem of diseased plant (A) just 

 above ground, enlarged three diameters : j, healthy vertical or 

 bark cells ; k, woody fibres diseased (brown) ; /, normal (white) 

 pith cells. E, early or first stage of fungus, called Dlplocadlum 

 stage : m, mycelium or prostrate hypha ; n, conidiophore ; 

 o, conidium or spore. x 300. F, second stage of fungus, 

 termed Fusarium stage : />, mycelial thread or prostrate hypha ; 

 f, conidiophore ; r, conidia or spores. x 300. G, final or 

 resting stage of fungus : /, mycelial thread with spores in 

 course of development ; /, matured resting spores ; u, resting 

 spore germinated and pushed germ-tube. x 300. 



TOMATO BLACK SPOT (Macrosporium tomato). 



The disease known as " black spot " or rot, also as 

 " black stripe " or blotch, spreads easily, being more 

 or less present wherever the Tomato is cultivated. It 

 is caused by the parasitic fungus named Macrosporium 

 tomato, but is closely allied to, if not the same as, the 

 Potato Leaf Curl fungus, M. solani. The fruit is 

 most frequently attacked, but the fungus is also often 

 present on the stem, producing the well-known " black 

 stripe/' and on the leaves, causing the condition 

 termed " curl ". 



The fungus has been regarded as a wound-parasite, 

 and thus gets into the tissues of the Tomato plant 



