REPORT OF THE DEPARTMENT OF 
BOTANY. 

NG oleae OL blebs Gr APPT 
Be UG 

EF. C. Srewart AnD H. J. Eustace. 

SUMMARY. 
J. During the summer of 1902 apple leaves over the greater 
part of New York were much wrinkled and distorted. On the 
under surface they were covered with irregular blisters of various 
Sizes caused by the separation of the lower epidermis from the 
mesophyll. Some of the blisters burst. 
The trouble was due to heavy frosts which occurred while the 
leaves were partially unfolded. Ice crystals formed between the 
lower epidermis and the mesophyll and forced them apart. There- 
after the epiderfhis grew no more while the parenchyma continued 
to grow and arch itself into wrinkles. The damage done was 
unimportant. 
II. In western New York there was a wide spread spotting, 
yellowing and dropping of apple leaves in July. This was the 
result of spraying with bordeaux mixture and insecticides. Be- 
cause of the protracted cold, wet weather the foliage was un- 
usually tender and susceptible to spray injury. Although at 
first the injury was thought to be serious it was found later that 
the injury was overbalanced by the good done in the prevention 
of scab. The spraying of apples should not be abandoned. 
Observations made in this connection indicate that the disease 
called apple leaf spot may not be of fungous origin as heretofore 
believed. 
—— 
*A reprint of Bulletin No. 220. 
