276 Diseases of Truck Crops 



The chlamydospores are thick walled, dark brown 

 bodies borne on the same mycelium as the endospores. 

 This type of spore is formed in great abundance on 

 the host and particularly within the affected tissue. 

 The ascospores are lenticular in shape and are borne 

 in asci or sacs within black perithecia. This stage 

 however has not been found on the pea or in pure cul- 

 ture. 



Control. Thielavia basicola is a soil-inhabiting 

 fungus. With infected pea fields, soil sterilization is 

 of course out of the question. The method of control 

 suggested is crop rotation. Investigations by John- 

 son 1 have shown that the following vegetable crops 

 are not subject to Thielavia root rot: potato, sweet 

 corn, sweet potato, cabbage, onion, parsnip, carrot, 

 beet, eggplant, and peppers. These crops may there- 

 fore be safely used in a crop rotation, the system of 

 which is best worked out by the trucker himself. 



POWDERY MILDEW, see BEAN, p. 262. 



POD SPOT 



Caused by Spharella pinodes (Berk, and Bl.) Niessl. 



Pod spot is a disease which is of even greater eco- 

 nomic importance than Thielavia root rot. The 

 disease does not confine itself to the pods alone, but 

 also involves the leaves and stems. The trouble 

 however is known by truckers as pod spot. 



1 Johnson, J. f U. S. Dept. of Agr. Jour. Agr. Research, 7 : 261-300, 

 1916. 



