164 Mortier F. Barrus 



favorable for infection occasionally to take place, at least when spotted 

 seed is planted. The disease is occasionally reported from such sections. 

 Complete freedom from anthracnose may be expected in those regions 

 where dry farming is practiced. Lauritzen (1919:32) suggests that the 

 variation in the amount of moisture in the air in different regions may be 

 an important factor in the distribution of diseases over the earth's surface. 



PROPHYLACTIC ASPECTS 



As early as 1893 a number of measures for the control of bean anthrac- 

 nose had been recommended. Among these were such as treating seed 

 with chemicals or hot water, selecting seed from healthy plants, spraying 

 with bordeaux mixture and other substances, working among the plants 

 only when they are dry, planting exclusively on ground that has not 

 produced diseased plants the year before, and selecting a dry, airy situation 

 with light soil. These recommendations, if carefully followed, will usually 

 result in the production of plants free from anthracnose. Doubt has 

 been cast, however, on the efficacy of certain of these recommendations, 

 and it is worth while to consider the advantages and disadvantages of 

 the various methods. 



Seed disinfection 



Seed treatment was first recommended by Halsted (1892:286), who at 

 that time used ammoniacal copper carbonate. Later (Halsted and Kelsey, 

 1895:30) he tried full-, half-, and quarter-strength bordeaux mixture, and 

 concluded that such treatment had but little effect in killing the mycelium 

 within the seed. Beach (1892:320), after experimenting with hot water, 

 bordeaux, ammoniacal copper carbonate, and potassium sulfide, found that, 

 while hot-water treatment resulted in the lowest percentage of plants with 

 anthracnose, the untreated seed gave a greater quantity of marketable 

 beans because of the better stand, and that even with severe treatment, 

 enough disease remained to injure the crop. Craig (1893), after soaking 

 seed for varying lengths of time in solutions of different strengths of 

 ammoniacal copper carbonate and copper sulfate, concluded that seed 

 can be treated cheaply and advantageously with copper compounds, 

 preferably ammoniacal copper carbonate. The best result he obtained, 

 however, was but 79 per cent of healthy plants, and but 73 per cent of 

 the treated seed germinated. Later (1898) he experimented with lysol, 



