24 MISC. PUBLICATION 4 4 0, U. S. DEPARTMENT OF AGRICULTURE 



some varieties that show resistance to the common bacterial blight are 

 not resistant to the halo type of blight or to bacterial wilt {Phy- 

 tomonas flaccwnfaciens (Hedges) Bergey et al.). 



The common bacterial blight organism may cause decay of beans 

 throughout a wide temperature range (34° to 95° F.), but develop- 

 ment is slow at 45 c and below. 



Neither spraying of plants nor seed treatment with chemicals or 

 with heat has given satisfactory control. 



(See 71, 74, 75. 76. 77. 81. 85, 92. 103. ISO. 131. 135, 155, 156.) 



BACTERIAL SOFT ROT 



{Erwinia carotorora (Jones) Holland) 



Snap beans under transit conditions are less frequently affected 

 with bacterial soft rot than are most other vegetables. However, 

 this decay often follows bacterial blight and frequently occurs simul- 

 taneously with some of the fungus rots. 



The pods become affected with bacterial soft rot only when they 

 are wet and warm. The causal organism does not enter through the 

 unbroken epidermis, a fact which probably accounts for the relative 

 unimportance of bacterial soft rot on the market, as beans are less 

 subject to breaks and bruises during harvesting and marketing than 

 most vegetables. 



For a complete discussion of this disease see Celery, Bacterial Soft 

 Rot, page 46. 



BACTERIAL SPOT 

 (Phj/tomoiias; trignae (Gardner and Kendrick) Bergey et al.) 



All varieties of lima beans tested have been found susceptible to 

 bacterial spot. Although the disease sometimes seriously affects the 

 vines and pods, so far it has not been an important factor on the 

 market. 



Small, brown spots surrounded by a water-soaked halo characterize 

 this disease on the pods. A straw-colored crust of exudate may be 

 apparent on the surface of some lesions. Spots may occur on any 

 part of the pod, and frequently they penetrate the walls, causing a 

 reddish discoloration of the seeds. Spongy excrescences are some- 

 times found protruding from the inner walls of the pod beneath the 

 surface lesions. 



Bacterial spot on the leaves is characterized by brownish- or purplish- 

 colored, irregular lesions. At first the spots appear as small brown 

 points on the upper surfaces of the leaves, but they are never water- 

 soaked, like those characteristic of most other bacterial diseases. The 

 centers of the large lesions turn gray or straw-colored, whereas the 

 margins remain glistening and purplish. Individual lesions vary 

 from one-sixteenth to one-eighth of an inch in diameter. Spots some- 

 times coalesce and form Large, ragged areas from which some of the 

 dead tissue eventually drops out. Reddish-brown or caramel-colored 

 streaks occur on the reins and petioles, and when the base of the leaf- 

 stalks is attacked the leaves are shed prematurely. 



Lesions on the stem vary greatly in size, some reaching a length 

 of 2 or :\ inches. Occasionally a Light wine-colored exudate appears 



