296 



FUNGOUS DISEASES OF PLANTS 



Inoculation experiments have also indicated that this fungus may 

 produce a rot through wound infections on apple, pear, quince, and 

 grape. It is believed that the fungus will become injurious only 

 under the conditions mentioned, and, therefore, it is necessary to 

 take indirect precautions only. Prevention of the scab, in particular, 

 will mean prevention of this rot, which is secondary to it. 



VII. RAMULARIA 



While the genus Ramularia is entirely parasitic, few plant dis- 

 eases of serious consequence are produced. Reference has already 



FIG. 131. CEPHALOTHECIUM 

 ROSEUM 



FIG. 132. AREOLATE MILDEW OF 

 COTTON 



been made to Ramularia Tulasnei (see Mycosphcerella Fragarice, 

 page 261). 



Ramularia areola Atk. This fungus, producing what may be 

 known as the frosty blight or " areolate mildew " of cotton, is very 

 characteristic. Small areas of the leaf between the finer veinlets 

 are .occupied by the fruiting hyphae. The latter are fascicled, and 

 numerous spores are borne. As a result of the abundance of the 

 fruiting hyphae and the avoidance of the veins an areolate appear- 

 ance is presented (Fig. 132). 



