MICHIGAN ACADEMY OF SCIENCE. 319 



Conclusion : 



From these experiments, no definite assertion can, of course, be made 

 as to liow far the spores can be carried by the wind. However, the 

 indications are that the spores of M. sarcinae forme, though comparatively 

 large and heavy might be carried a sufficient distance from their source 

 to reach and infect other fields of red clover. Outdoors, where a much 

 higher elevation is obtainable, this distance should be much greater than 

 in the tube experimented with. 



This point should be considered, however. Under field conditions, 

 especially in damp weather, many spores fall to the ground and are 

 caught by the wet soil or between the lower parts of the plants. Spores 

 so situated would not, therefore, be in a favorable position for dissemina- 

 tion by the wind. 



CONTROL. 



Any metliod of controlling the disease by the application of sprays is 

 impracticable. Cavara's suggestion that the field be watched and the 

 diseased leaves be removed as they appear, would, to say the least, be 

 very difficult to follow where clover is grown on a large scale. The 

 mowing of the young crop as soon as the disease appears, has been 

 suggested as a remedy for several diseases of red clover. However, in 

 the case of M. sarcinae forme, the presence of the cut, diseased leaves 

 in the field would be a source of infection to the new crop especially 

 during rainy weather. The close relation to relatively high humidity 

 indicates that well ventilated, well drained fields will suffer less from 

 the disease than those in less favorable locations. 



The value of seed disinfection is not at all known, nor is the role of 

 the spores carried on the seed determined. The wide-spread distribu- 

 tion of the fungus, points to a seed dispersal of the fungus. The strong 

 possibility of infection from volunteer clover or from the soil already 

 infected from nearby fields by wind borne spores, makes any recom- 

 mendation of seed treatment as yet unwarranted. 



The ultimate solution of the problem of the control of this disease, 

 and for that matter, the control of all field crop diseases, is the breeding 

 of resistant varieties. In the case of Anthracnose of clover (Colletotri- 

 chum trifolii), this has been done. Bain and Essary (1906), in looking 

 for a means for controlling this disease in Tennessee, began by selecting 

 uninfected plants growing in a badly diseased field. From this selection, 

 a strain of clover has been bred which is fairly resistent to the disease. 

 The method of selection could probably be used in producing a resistant 

 strain of red clover against any of its diseases. The author has seen 

 occasional plants during the summer which were unaffected though grow- 

 ing in the midst of badly diseased plants. 



