The Bacterial Diseases of the Bean 



45 



Figure 10. opaque drops containing bacteria on the surface of bean stems 

 systemic ally infected with phytomonas medicaginis var. phaseolicola 



may sometimes find a light, silvery crustation due to the bacteria oozing to 

 the surface and drying down. This is a very delicate crust and may be 

 washed away quickly during a rain. 



When the bacteria pass through the vascular system of the pedicel and 

 enter the pod, a rather irregular lesion along the suture may be produced 

 (Plate IV, A). Such a suture lesion differs in appearance in no respect 

 from those of the spots as described above, except in position and outline. 

 These lesions are indistinguishable from those produced by Phyt. phaseoli 

 and Phyt. flaccumfaciens. 



On the seeds 



This disease may involve the entire seed or only a small part of it. 

 On white seeds the distinguishing characteristic of the spot is the maize 

 yellow to cream color of the affected area. Severely infected seeds are 

 small and wrinkled, and may be completely colored by the pathogene. 

 On colored seeds the spots due to Phyt. medicaginis var. phaseolicola are 



