APPLE DISEASES. 187 



For inoculation of leaves, seedlings grown in the greenhouse, 

 trees one year from the bud brought into the greenhouse early 

 in the spring and grown in pots, and both old and young leaves 

 on branches of bearing trees in the orchard were used. Sterile 

 water containing an abundance of the Coryneum spores was 

 sprayed on the leaves with an atomizer. Seedling trees 3 to 4 

 months old bearing a few leaves were placed in a moist cham- 

 ber and kept there for a few days after inoculation. The year 

 old trees were also in some cases placed in a moist chamber 

 made by using a tall bell- jar arranged as shown in Fig. 17 with 

 tubing so connected that water dropped on sheets of blotting 

 paper under the bell-jar at such intervals as to make a moist 

 atmosphere. 



As a result of these inoculation experiments, it was found 

 that C. foliicohim did not grow on uninjured leaves. When 

 spots in the leaves were killed with a heated needle it was found 

 that the fungus developed readily on the dead spots. One 

 week after inoculation of such leaves there were numerous 

 masses of spores on the dead spots which microscopic examina- 

 tion showed to be spores of Coryneum. Observations of these 

 leaves for several weeks showed that these spots did not 

 increase in size by the invasion of the healthy tissue by the 

 fungus mycelium. Neither did infections occur on other 

 healthy leaves from spores produced on the dead spots. 



The results of these inoculation experiments are made more 

 valuable by the fact that, at the same time that they were being 

 carried on, the writer studied a number of other fungi com- 

 monly associated with leaf-spot. Phyllosticta limitata Pk., 

 Coniothyrium pirina (Sacc.) Sheldon, Sphceropsis malorum Pk., 

 and a species of Phoma probably Phoma mali Schulz. et. Sacc, 

 were tested as to their ability to cause leaf-spot, and of these 

 it was found that only Sphcuropsis inolorum Pk. caused the 

 disease on uninjured leaves although the other fungi developed 

 readily on dead spots in the leaves. 



The first inoculations made to determine whether C. foliico- 

 him could develop on living apple wood and thus cause cankers 

 were made May 4, 1909, on a young tree growing in a pot in 

 the greenhouse. Incisions were made in the bark on the 

 branches in 7 places and material of the fungus consist- 

 ing of both mycelium and spores from a young culture 



