,12 



PLANT DISEASES 



frequently attacked, although the fungus sometimes passes 

 on to the young fruit also. Small brown spots appear first 

 on the young leaves, which gradually increase in size until 

 the greater part of the surface is covered ; the leaves 

 gradually become blackish-brown, shrivel, and die. The 



Fig. 83. — Cladosporium fiilvum. i, under surface of a 

 diseased tomato leaf; 2, a tuft of conidiophores bearing 

 conidia, x 300. 



under surface of the leaf corresponding to the dark patches 

 is covered with a short felt of a rusty-brown colour. This 

 felt consists of closely packed, sparingly branched clusters 

 of coloured conidiophores bearing elliptical, one-septate 

 conidia at their tips. The sporophores are knotted or 

 swollen at the joints. Blackish stripes are often present 

 on the stems of diseased plants. 



