62 U. S. DEPARTMENT OF AGRICULTURE. 



firm and not disintegrated. The lesions are often cracked 

 or fissured on the surface as a result of root growth, and 

 may be accompanied by some disfiguration of the root due 

 to checked growth. 



This disease is of widespread occurrence. Both red and 

 white varieties are susceptible. The fungus persists in the 

 soil and often causes damping-off of seedlings. 



Badly affected roots often are found in the market, but 

 are not considered edible, and their presence lowers the 

 value of the bunch. 



Control involves crop rotation or soil sterilization. Badly 

 affected roots should not be sent to market. 



Ref. (16). 



RADISH: MISCELLANEOUS DISEASES. 



DOWNY MILDEW. 



Cause: A fungus (Peronospora parasitica). 



Downy mildew causes angular spots on the leaves, 

 bounded by the larger veins. These spots are yellow in color 

 when viewed from above, and the under surface is covered 

 with a white felt-like outgrowth of mold. 



This disease often is found in the market but is of no 

 importance since the root is not attacked. 



WHITE RUST. 



Cause: A fungus (Cystopus candidus). 



The symptoms of this disease on the leaves are small, 

 irregular lesions bearing on the under surface smooth, pure 

 white, porcelain-like cushions or blisters. These rupture, 

 allowing the spores to escape, and the lesions are then 

 recognizable by the torn edge of the empty pustule. Often 

 these lesions cause marked distortion in the leaves and other 

 affected parts. 



Since this disease does not occur on the roots, it is of no 

 importance in the market. 



ROOT ROT. 



Cause: A fungus (Rhizoctonia). 



This disease is marked by a rather large brown circular 

 lesion on the side of the root in which the tissue is rotted 

 as in watery soft rot. 



This has been found occasionally in the market. 



NEMATODE DISEASE. 



(See Nematode Disease). 



RADISH; SLIMY SOFT ROT; BACTERIAL ROT. 



(See Slimy Soft Rot). 



RUTABAGA: DRY ROT. 



(See Radish Root Rot). 



