DISEASES OF LEGUMINOUS PLANTS 341 



results. There are notable varietal differences in resistance, 

 but the adoption of this means of control is complicated by the 

 existence of strains of the fungus which attack varieties resistant 

 to other strains. Wells' Red Kidney is reported to be very 

 satisfactory in this respect, and it is expected that resistant 

 white types will be made available. 



A very considerable degree of freedom from the disease can 

 however be secured by taking precautions against planting 

 infected seed. Pods should be selected which have no spots 

 whatever upon them. It is not sufficient to select unspotted 

 seed, since a slight infection may not be noticeable. An infection 

 so slight as this upon a pod would have little significance, since 

 the fungus would not have penetrated to the seeds within. It is 

 advisable, however, in order to prevent infection from such a 

 source, or from merely adherent spores, to dip the pods for ten 

 minutes in corrosive sublimate solution (i part to 1000 of water). 

 The seed so obtained should be used to plant a seed plot on clean 

 ground. Cases arising after this treatment should at the worst 

 be few, and capable of elimination by hand-pulling. 



In using imported seed the best that can be done is to reject 

 all those which show signs of injury (which in many samples 

 examined have been very numerous) and to treat the remainder 

 with a disinfectant. 



Bacterial Blight. 



This disease which is widespread in the United States has been 

 frequently noticed on beans in these islands. It is caused by 

 Bacterium phaseoli E.F. Sm. 



The signs of its attack on the seed are, in light cases, yellow 

 spots or blotches, not definitely circular, frequently on the 

 side of the seed which was attached to the pod ; in severe cases, 

 yellowing and shrivelling of the whole seed. On the seed-leaves, 

 small amber-coloured spots appear, with which may be associated 

 a light yellow slime. On the foliage leaves the disease produces 

 irregular water-soaked areas, which are usually bordered with 

 distinct yellow or red hnes. These areas gradually enlarge 

 until the entire margin, or half the leaflet, may be involved. The 

 watery areas later become brown and dry. On the pods, watery 

 pustules are first formed, which develop into amber-coloured 

 irregular blotches with uneven green centres ; clumps of the 

 bacteria ooze out, and dry into yellow crusts on both leaves 

 and pods. The general appearance of a field, when the prevalence 

 of humid weather conditions has led to a severe infestation, 

 is described as suggesting that the plants had been drenched 

 with hot grease. At a later stage the older leaves look dry and 

 burnt, and excessive new growth occurs in the attempt to provide 

 new foliage. Fruiting is seriously interfered with, and the pods 

 cease to fill out. 



