Bean Anthracnose 171 



weather, and so weeds of various kinds grew up among the bean plants 

 On October 4 the plants were found to be generally affected with anthrac- 

 nose. From the row 75 plants were selected, one plant at every pace. 

 On these plants there were 209 pods, of which 137 were affected with 

 anthracnose, 67 were not spotted, and 5 were doubtful. About 40 rods 

 southwest of the end of this row was a large field of Red Kidney beans 

 which were badly affected with anthracnose. It was concluded that 

 the first infection of plants in the row planted with clean seed came from 

 spores carried from the affected Red Kidneys by some animal, and, since 

 the tall weeds about the beans kept them moist most of the time during 

 the rainy season, and since they were planted in drills so that the plants 

 were in contact with one another, the disease readily spread along the 

 entire row. 



These trials seem to indicate that the use of clean seed is not altogether 

 successful in producing a crop of beans free from anthracnose unless 

 the season is dry, under which condition there is no loss from the disease 

 in any field. The experiments are reported because the results are such 

 as may be expected in such cases. So far as observations were made 

 in these and in other experiments, clean seed always produced anthracnose- 

 free seedlings in the field, and this is all that can be expected of clean 

 seed. Infection, when present, must have taken place from an inoculum 

 of a source other than the seed. In some cases this came early from old 

 affected vines or from near-by affected plants. Infection will always 

 be likely to occur from such sources under favorable weather conditions 

 unless precautions are taken to prevent it. Since clean seed can be 

 depended upon to produce seedlings free from anthracnose, the question 

 becomes one of deciding whether or not the presence of affected seedlings 

 in the field is a sufficiently great menace to warrant the use of clean seed. 

 The writer, from observations of his own experimental plots and of many 

 fields in which clean seed as compared with affected seed has been used, 

 is convinced that the presence of such affected seedlings is a menace 

 that warrants the grower's going to considerable pains and expense in 

 order to obtain healthy seed. Growers generally will probably prefer 

 to buy clean seed if they can get it, rather than to take the trouble to 

 produce it. But some one must produce it if it is to be had, 

 and the question of production is the one concerned here. It is true 

 that following dry seasons there will be but little difficulty in obtaining 



