8 



organisms present that could possibly occasion such sud- 

 den and extensive injury, and after repeated attempts to 

 induce the disease by inoculation, I am forced to believe 

 that conditions of weather, such as showers followed by 

 extreme heat, occasionally kill the foliage of some of our 

 shade trees. The tree which has suffered most in this 

 neighborhood during the past three years is the Catalpa, 

 and I present herewith a figure of one of these trees as it 

 appeared soon after it became affected. One of my pur- 

 poses in calling attention to this trouble is to point it out 

 as an affection not due to insects, and not very easy to 

 guard against. Inquiry has reached me occasionally 

 with reference to it. I do not know anything likely to 

 prevent its occur ance except shade ; and I am disposed 

 to think that the trees which are subject to it are those 

 whose habit it is to grow in thickets, and which are not 

 therefore adjusted to complete exposure to the sun's 

 rays. 



Kinds of Pests Attacking Shade Trees. 



The parasites of our shade and ornamental trees are 

 of two sorts : insect and fungus. The latter are only oc- 

 casionally abundant enough to call for attention. But 

 they may during warm damp seasons do quite as much 

 harm as insects. Their attacks are most generally made 

 on the leaves and tender growths of twigs, where they 

 produce variously colored spots and blotches, and in the 

 end kill the tissue. The soft maple {Acer dasycarpum) 

 and red maple ( A. ruhrum) are subject to the attacks of 

 a fungus {Rhytisma acerinum) in the Mississippi valley 

 that often works much injury to the leaves. It produces 

 a dense black spot varying from .25 to .50 inch in di- 

 ameter, with its upper surface coarsely wrinkled and 

 slightly convex. The leaves of the yellow poplar (tulip- 

 tree) are also subject to the attacks of a fungus produc- 



