64 PROTPX.TION OF PLANTS — 1924-25 



various Phaseoli." He then goes on to state that while Halsted illustrates leaf 

 spots from the organism that he worked with, at the same time as spots on the 

 pods, he (Smith) had not been able to get infection on the pods with his own 

 organism. In looking up Halsted's pictures of "Pod blight of linia beans", 

 it was interesting to note that they do not differ very widely from the picture 

 taken of the original material for the present cultures. 



Harter in his comparison of the disease with that caused by Phoma sub- 

 circinata states that "The spots are smaller, more nearly round and the pycnidia 

 are smaller and fewer in number. 



The peculiarity of the organism studied here is that it was isolated from 

 a pod that had large lesions but in the inoculation experiments it caused a leaf, 

 stem and flower spot with only very slight spots on the pod. 



The disease. 



So far I am under the disadvantage of having only examined the disease 

 critically on beans artificially inoculated under greenhouse conditions, and on 

 leaves it is rather like the description given by Smith but it was not found 

 that the lesions are confined to the leaves. Lesions were easily obtained on the 

 flowers, flower-buds, stems, leaf petioles and pods. They are only slight on 

 the pods, however, and frequently appeared only as fine flecks. 



On the leaves. 



Smith's description of a light centre and a darker margin will only apply 

 to about one-half of the spots. Many of those observed having a distin tly 

 dark centre and then a lighter ring w^th a dark margin next the living tissue. 

 The leaf spot is also marked with dark lines formed by the leaf veins being a 

 darker brown than the other tissue. 



On the flowers and flower buds. 



The worst feature of this disease as observed in the greenhouse was the 

 severity with which the developing flower buds were attacked. The lesions 

 formed on the unfolding petals and sepals and when a flower bud was once 

 attacked it ceased normal development, turned brown and dropped off within 

 a few days. It was observed that the parts of the flower bud were the most 

 readily attacked. 



On the stems and petioles. 



The lesions were a deep reddish brown and ranged in size from 1 to 20 mm. 

 in length. Some were observed to be much longer but as they continue develop- 

 ing it was considered that they resulted from the coalescing of several. The 

 lesions were generally narrow extending lengthwise of the stem but as the plant 

 matured thev widened and in some cases extended entirely, around in the case 



