132 Mortier F. Barrus 



in other ways comes into contact with the now exposed under surface of 

 these leaves. The stem may also become inoculated with spores that 

 have been washed down from the cankers on the cotyledons, especially 

 the base of the stem just below the surface of the soil, where moisture 

 conditions are favorable for the germination of the spores. Frank 

 (1883b: 522) says that after affected cotyledons fall from the growing 

 seedling, the fungus continues to grow in them and produces spores in 

 great abundance which are washed by rain into the soil and bring about 

 an infection of the plant in this way. Spattering of contaminated water 

 and of soil also serves to inoculate the seedling; this is discussed more 

 fully later. 



Dipping seed in a suspension of spores just before planting will bring 

 about an infection of the cotyledons and other parts of the seedlings, as 

 has been shown by Edgerton (1910:41) and verified by the writer. Gain 

 (1898) proved that the soil can become contaminated and serve as a 

 source of inoculum. 



Seeds planted in soil to which water containing spores of this fungus 

 is applied will also produce infection. On August 22, 1910, thirty-six 

 clean bean seeds were planted in twelve pots and watered with a suspension 

 of spores of Colletotrichum lindemuthianum. As a check, six seeds were 

 planted in two pots to which water without spores was applied. On 

 September 6 thirty-one plants had appeared in the twelve pots, of which 

 thirty, or 96.8 per cent, were infected. None of the six plants that appeared 

 in the check pots were affected. On August 30, 1910, fifty clean seeds of 

 the variety Golden Refugee were planted in a flat in clean soil, and water 

 containing spores of C. lindemuthianum was poured over the surface 

 until the soil was wet. On September 9 forty-nine plants had appeared, 

 of which six showed anthracnose lesions. No later observations were 

 made. 



Longevity of fungus in soil 



In order to find out whether spores washed to the soil would remain 

 viable over winter, the following experiment was carried out. On 

 November 27, 1916, twenty-five 8-inch pots were filled with loam and 

 sterilized in the autoclave for three hours at twenty pounds pressure. 

 On December 15, fifty test-tube cultures of C. lindemuthianum grown on 



