SUMMER MEETING AT BUTLER. 71 



The conditions which will be likely to cause the development of the 

 bacterial germs are those mentioned as applying to vegetable para- 

 sites in general. If the tree makes a late growth and fail to ripen the 

 wood, the alternate freezing and thawing of the unripened tissue dur- 

 ing the winter will bring about such a condition of the cells as will 

 invite the development of the germs. The same condition may be 

 produced by the rays of the sun when the trees grow in turf on soil in 

 which one or all of the soluBle elements required as food by the plant 

 have been exhausted. 



The scahs and cracks which disfigure the surface of certain varieties 

 of apples and pears are caused by a fungus which has received the 

 name of Fusicladium. 



The fact that these fungoid growths only infect trees when of a low 

 vitality, or when the tissues are in an abnormal state, was clearly shown 

 by the chemical and microscopical investigations of the peach yellows 

 carried on by Profs. Goessmann and Maynard, of the Massachusetts 

 Agricultural College. On the light soil of New England the weakness 

 was induced by the special exhaustion of the soil. Our trees are often 

 affected by the same cause, but on cur heavier soil we have more to 

 fear from a rank growth induced by the stimulating effect of the decay- 

 ing vegetable matter in the ground, or from the cessation of growth 

 during the spring, after the leaves develop, caused by the low tem- 

 perature of the saturated soil. The experiments at Amherst, and the 

 more recent ones of Prof. Penhallow at Houghton Farm, show that the 

 attack of the peach yellows can be prevented, and that a cure can be 

 effected by the application of mineral fertilizers. 



The trees first experimented upon are now fifteen years old. When 

 they were taken in hand eight years ago they were badly infected. 

 They were cut back and heavily manured with chemicals. The trees 

 were brought back to a healthy state, and have since produced full 

 crops in favorable seasons. 



For all of these diseases the preventive measures above men- 

 tioned as to location, drainage, condition of the soil, and health of the 

 trees used, will often be sufficient to ward off attack. The trees should 

 be carefully watched — protected from insects and vermin. The land 

 should be seeded in grass if the trees make too rapid a growth, while 

 if the growth is weak, or the trees show signs of the presence of these 

 parasites, they should receive an application of some mineral fer- 

 tilizer. 



For this purpose a mixture composed of 50 pounds of muriate of 

 potash, and 100 pounds of ground bone, used at the rate of from two 

 to ten pounds per tree, will generally secure a healthy growth. 



