70 



FUNGOID DISEASES 



Cause. — The disease is caused by the parasitic 

 fungus Ascochyta pisi, which destroys the tissues, 

 producing discoloured spots. The disease is trans- 

 mitted in infected seeds (see Fig. 20, c and b), and 

 also in the diseased stems and leaves, if these are 

 allowed to remain on the around over winter.^ 



Fig. 20. — Pod of pea suffering from Spot Disease [Ascochyta pisi) (s) ; 

 below a cotyledon (half of a pea) (r) with diseased centre (d). 



Preventive Measures. — 



Sow seeds from healthy plants, or from 

 fields not affected ; if suspicious of the 

 seed, sow only plump unspotted seeds. 



Do not grow peas two years in succession 

 on the same field. 



^ Beans, particularly haricots, suffer from a disease known as 

 anthracnose, and caused by Colletot?-ichuni Ii7idemiithia77um. This 

 causes brown spots on the pods, seeds, and also on the stem of 

 seedling plants, as well as brown lines along the leaf veins. It is 

 not easily controlled, but the same methods should be adopted as 

 for the spot disease of peas. 



