Bean Anthracnose 179 



observed that hilling young plants tends to prevent the spread of the 

 disease by covering the lesions at the base of the stem, thus hindering 

 the spores from escaping. The small lesions heal afterward, and, while 

 the larger ones may develop and rot the plant, the spores produced are 

 not able to be disseminated. Edgerton (1909:5) suggests that danger 

 of the disease's spreading from affected seedlings may be lessened if the 

 field is not entered until the cotyledons have dropped off. 



Leaving the plants untouched while wet 



As has been noted (page 176), a diseased plant may exist in a field of 

 beans without the disease spreading materially to other plants. If, however, 

 when the plants are wet, some agent passing through the field comes in 

 contact with the diseased vine, spores are likely to be distributed to 

 plants beyond. A very active agent in distributing spores is a horse and 

 cultivator, or, even more so, a person picking beans. Growers of a large 

 acreage like to start work in the fields early, and yet there are many 

 mornings during the growing season when the dew remains on the plants 

 until after nine o'clock. It is very important that operations in the bean 

 field should be postponed until the vines are dry. The observance of this 

 simple precaution will do much toward preventing a general infection of 

 the field. 



Destroying diseased vines in the fall 



Since the fungus lives over winter on the old pods and vines, these may 

 serve as a source of infection to young beans growing near them the 

 following spring. Galloway (1889) recommends the burning of all diseased 

 vines and pods. Both Harvey (1894) and Cobb (1894:383) believe it 

 advisable to remove and destroy all diseased vines after harvest if the 

 same land is to be used for beans the following year. Whetzel (1906:209) 

 states that diseased pods and stalks should be removed from the field. 

 The old vines and pods are not so often a source of inoculum as are the 

 affected seeds, and yet it is unwise to disregard them altogether. One 

 should not go to a considerable expense to remove and destroy old 

 affected vines from the field, but should prevent their coming into contact 

 with the new crop as far as it is practicable to do so. A rotation of the 

 bean crop, and the application of manure containing bean refuse to other 

 than the current or the following year's bean field, are helpful measures. 



