260 Diseases of Truck Crops 



see, Louisiana, Colorado, Missouri, Indiana, Virginia, 

 Kentucky, Florida, and Oklahoma. 



DISEASES OF THE BEAN {Phaseolus vulgaris) 



Bean growers annually lose heavily from various 

 bean diseases. There is no other truck crop, potatoes 

 excepted, which has received as much attention from 

 plant pathologists as the bean. With our present 

 knowledge, many of the diseases may be controlled. 



Blight 



Caused by Pseudomonas phaseoli Ew. Sm. 



Symptoms. If the weather is wet during planting 

 time, the seed may rot in the ground and never germi- 

 nate. At other times the root of the young seed- 

 lings may decay and the result will be a very poor 

 and uneven stand. In dry weather a better germi- 

 nation is obtained, but the disease works on the older 

 plants in irregular spots in the field. Due to the 

 lack of a normal root system, the affected plants 

 are yellowed and wilted at daytime, but they slowly 

 revive at night. Should the weather become muggy 

 in midsummer, infected fields appear as though they 

 were drenched with hot grease, the leaves having a 

 burned appearance (fig. 46 a) . As a result, the injured 

 plants seem to make a desperate attempt to produce 

 new foliage which in turn becomes affected, hence 

 the pods cease filling and ripening is very uneven. 



In carefully examining diseased seed, it is found to 

 be yellowed and shriveled ; or, in light cases of attack, 



