206 Diseases of Truck Crops 



Shot Hole 



Caused by Septoria armoracice Sacc. 



Shot hole is a very serious disease which attacks 

 the foliage of horseradish. Diseased leaves turn 

 yellow and become peppered with round spots, 

 whitish in the center, surrounded by a pale yellow 

 border. The spots drop out and give the leaves 

 a ragged shaggy appearance. The pycnidia of the 

 fungus are formed in the center of the spots previous 

 to their dropping out or on the remaining margin 

 of the spot. 



Macrosporium Black Mold 



Caused by Macrosporium herculeum E. and M. 



This mold is confined to the leaves only. Late 

 in the summer the leaves are attacked by round 

 spots which at first are whitish, and later become 

 coated with a black mold made up of the spore bodies 

 of the fungus. Horseradish may also be attacked 

 by another form of black mold, Alternaria brassica 

 (Berk.) Sacc, see p. 196. 



White Mold 



Caused by Ramularia armor acicE Fckl. 



White mold is frequently met with on foliage of 

 the horseradish. The spots are indefinite, irregular, 



