238 



MANUAL OF TREE DISEASES 



veins, large areas are killed and the tip of the leaf frequently 

 dies. The dead areas become light brown and very much 

 wrinkled. Minute darker brown pustules the size of a pin- 

 head or smaller are scattered over the dead area. Small 

 globules of sticky spores are developed from these pustules 

 in rainy weather and the spores may be washed to all parts 



Fig. 44. — Leaf-blight of oak. 



of the tree, causing the infection of other leaves. The twigs 

 are sometimes affected, but this symptom is less frequent in 

 oak than in sycamore. The life history of the causal fungus 

 is imperfectly known and is discussed under sycamore dis- 

 eases, page 333. Control measures are also the same as for 

 this disease on sycamore. 



