258 Bush-Fruits 



by the amount of leaf-tissue which is destroyed. Attempts to con- 

 trol the trouble by spraying seem thus far not to have given results 

 of much promise. 



LEAP-RUSTS 



Two species of Phragmidium, one on blackberries, the other on 

 raspberries, are prevalent and sometimes abundant, though seldom 

 considered injurious. They are found on the under side of the leaves 

 and would be difficult to combat. Blackberries are sometimes at- 

 tacked also by late rust which, as its name implies, appears late in 

 the season. It is caused by the fungus Kuehneola uridinis (Lk.) 

 Arth. 



DOUBLE-BLOSSOM (Fig. 37) 



Fusarium Ruin, Winter 



This disease is very destructive on certain varieties of dewberries 

 and blackberries, from New Jersey southward along the coast, but 

 especially in the Delaware-Maryland Peninsula. It is known to 

 occur on several species of Rubus but is especially severe on Lucretia 

 dewberry and Rathbun blackberry. It is re- 

 ported to have been so destructive to Lucretia 

 on the above peninsula as to drive one-half 

 the growers out of the business. The life of a 

 field of berries is often shortened two or more 

 years by its ravages. 



The disease becomes noticeable when the 

 leaf -buds open, the diseased buds usually being 

 larger than normal ones. They are often ac- 

 37. Double- companied by One or more small buds at the 

 side. The diseased buds produce " witches' 



brooms" instead of normal shoots. These may consist of a mass 

 of short slender twigs or of one good shoot, somewhat reduced, 

 with several short deformed ones. Such diseased shoots often remain 

 green after the old canes are dead. The blossoms usually have en- 

 larged, thickened sepals and petals, and sometimes more than the 

 usual number. The petals are generally wrinkled, giving the blos- 

 som the appearance of being double. 

 The disease generally appears about the second year of fruiting 



