142 DISEASES OF THE SWEET PEA 



probably been seen by a number of grow- 

 ers. 



Symptoms. Mosaic is readily distin- 

 guishable by a yellow dotting or mottling 

 of the leaf, presenting in some instances 

 a beautiful mosaic structure, whence its 

 name (fig. 26) . Affected leaves linger for 

 a time but they eventually lose all their 

 chlorophyll and soon drop off. Another 

 symptom of this disease is a curling of 

 leaves (fig. 27) resembling the curling in- 

 duced by the green Aphids, but in this 

 case the insects have no association with 

 it. The disease makes its appearance after 

 the seedlings are from two to three weeks 

 old. Often, the trouble is so serious and 

 the curling so pronounced that the plants 

 thus affected cannot make any headway 

 and remain dwarfed. An attempt is made 

 by these curled plants to produce a few 

 flowers, but the latter are borne on very 



