DISEASES OF CROPS 211 



BLACKBERRY, DEWBERRY AND RASPBERRY 



Crown Gall. See Apple. 



Leaf Spot (Septoria rubi, West) occurs on the leaves of these bush 

 fruits, causing small white or ash-colored spots with brown or reddish mar- 

 gins. Close examination shows very small black dots in each spot. It is 

 frequently the cause of considerable damage. 



Treatment. Spray in the spring with Bordeaux mixture. 



Anthracnose (Glceosporium venetum, Speg.). This disease attacks 

 the young canes of these fruits, causing small purplish spots which enlarge 

 and become grayish or dirty white in the centers. When severe, it causes 

 the canes to crack and die, the leaves to be dwarfed and the fruit to ripen 

 prematurely. The disease also occurs on the leaves, causing them to 

 develop unequally. 



Treatment. Cut and burn the diseased and dead canes soon after 

 picking the fruit. Spray with Bordeaux mixture in the spring and also as 

 soon as possible after the beny season. 



Orange* Rust (Gymnoconia interstitialis [Schlecht], Lagh.). This 

 disease is very abundant in the spring of the year, causing a dense coating 

 of red rust (spores) on the under surface of the leaves. The fungus grows 

 within and may spread throughout the entire plant. 



Treatment. Dig and burn the entire plant. Spraying with Bordeaux 

 mixture will prevent the infection of healthy plants, but is not a practical 

 treatment. 



Double Blossom (Fusarium rubi, Wint.). This disease is especially- 

 abundant on the Lucretia dewberry, the black diamond or Brazil 

 blackberry and also occurs upon other varieties of blackberries and 

 dewberries. The fungus lives within the buds, causing them to 

 form witches' brooms of slender shoots with deformed or double 

 flowers producing little or no fruit. The infection of the new buds which 

 are forming for the next year occurs when the diseased flower buds are 

 opening. 



Treatment. The disease can be greatly reduced by picking these 

 deformed leaf buds soon after they open and before the opening of the 

 flower buds. Select plants so far as possible from fields free from the 

 disease. 



Cane Blight (Coniothyrium fuckelii, Sacc.). This disease of the rasp- 

 berries attacks the canes, causing them to be lighter in color, with smoke- 

 colored patches. The foliage of diseased canes wilts and dies very much as 

 from drought. The disease penetrates wounds, frequently those made by 

 pruning. It is readily distributed in nursery stock and will persist in the 

 soil for several years. 



Treatment. Rotate the crops and use only healthy plants for 

 setting. 



Yellows. This disease is confined to the raspberries. It resembles 

 peach yellows and should be treated in the same manner. 



