Press Bulletin. 289 



ease often developing rapidly during shipment. Where the beans 

 are left on the vines to ripen the disease gradually works through the 

 pod and attacks the seed, forming pits or discolored places in the 

 bean. Here, when the seeds are dried, the fungus remains dormant, 

 only to become active again the next season when the diseased coty- 

 ledons are lifted above the soil on the growing stalks. Diseased seed 

 may be detected by the discolored areas on the coat and are usually 

 imperfect, shriveled or light in weight. 



NATURE OF THE DISEASE. 



The anthracnose of beans is not caused by weather conditions any 

 more than a crop of corn is caused by the weather. If there are no 

 seeds of com in the soil the most favorable weather conditions can- 

 not produce a crop. There will be no anthracnose if the fungus is 

 not present in the soil or in the beans themselves when they are 

 planted, or if it is not carried to healthy beans from diseased plants 

 by insects or some other means. Wet weather does not cause 

 Bean Anthracnose. It is caused by a minute parasitic plant which 

 attaches itself to the growing bean, spreads through the tissue of stem, 

 leaf or pod, destroying the tissue and using the substance for its own 

 nourishment. The fungus consists entirely of tiny colorless threads 

 in the tissue of the bean and the spores which are produced at the 

 surface of the black spots. The spores are too small to be seen with 

 the naked eye except where they occur in masses. These spores are 

 held together by a gummy substance which is easily dissolved in 

 water. After a heavy dew or rain these spores may easily become 

 attached to insects which visit the diseased plants and so be carried 

 to healthy ones. Hoeing the beans when they are wet is also sure to 

 scatter the spores in flying drops of water. 



RELATION OF THE WEATHER TO THE DISEASE. 



While the weather is not directly responsible for the disease, it has 

 very much to do with its prevalence and destructiveness. Good 

 weather is very essential to a corn crop, but the grower may, by 

 judicious cultivation, do much to make up for unfavorable weather 

 conditions. So in the case of the anthracnose, by a proper under- 

 standing of the nature of the disease the bean grower may be able to 

 so control it that he can grow a good crop even in seasons very favor- 

 able to its development. 



When there is an abundance of moisture the spore masses quickly 

 dissolve and the spores are easily distributed by insects, rabbits, or 



