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FUNGOID DISEASES 



Symptoms. — The first sign of the disease Is the 

 appearance of yellowish-brown thumb-like marks on 

 the leaves, which, as digestion and decomposition 



H 



Fig. 21 (B). — Cross-section through a leaf at one of the diseased spots (D) ; 

 (U) upper and (L) lower side of leaf; (P) palisade tissue ; (S) spongy- 

 tissue ; (W) the wall of the plant cell ; (H) the hypha of the fungus ; 

 (Co) the conidiophores ; (C, C, C, C) the conidia. 



proceed, become darker In colour (Fig. 21, A). 

 Around the outer edge of these spots a ring of white 

 felt-like growth may be seen In very moist weather 

 on the under side of the leaf (Fig. 21, B). 



