RASPBERRY DISEASES 407 



same from year to year and in no case disastrous or fatal to the 

 affected plants. 



Some varieties suffer more than others. In general, black 

 raspberries are more susceptible than red varieties. Among the 

 red raspberries the Antwerp is injured to a considerable degree, 

 and the spots are very conspicuous thereon. The Cuthbert, 

 on the other hand, is but slightly affected. Among the black 

 varieties the Cumberland is susceptible. 



Symptoms. 



Although anthracnose is preeminently a disease of the canes, 

 no part above the ground is free from the attacks of the patho- 

 gene. The disease first appears on the canes when they are 

 from six to ten inches high. Both fruiting and non-fruiting 

 canes (suckers) are affected. On the suckers the disease shows 

 more commonly at the base. In any case the larger and older 

 lesions are found toward the base of the cane. The course of 

 development appears to take place from below upwards. 

 Younger and smaller lesions always are to be found toward the 

 tip of the cane. The spots (Fig. 119) are at first small, purplish 

 and variously scattered. Their form is elliptical. As the 

 lesions become older they increase in size and the color, partic- 

 ularly at the center, becomes grayish white (Fig. 119). The 

 margin remains purplish. It is slightly raised, and thus the 

 healthy and diseased tissues are sharply separated (Fig. 119). 

 In more advanced stages the affected areas coalesce and the 

 cane appears irregularly blotched. These blotches are often 

 an inch and a half long and sometimes girdle the cane. The 

 affected cane attempts to heal the wound so that old spots have 

 a rough, scabby aspect. Sometimes canes are severely cracked 

 (Fig. 119), in which cases the pith is exposed. Often the 

 affected areas present an appearance of large irregular cankers 

 in which the surface is sunken and the bark split lengthwise. 

 Canes thus affected cannot function properly, and as a result 

 they become sickly. Their leaves are dwarfed and the fruit, 



