MAINE) AGRICUI^TURAL EXPERIMENT STATION. I91O. 387 



ing width extending entirely around the fruit midway between 

 the stem and calyx. 



Frost injury of the leaves. Very frequently associated with 

 frost bands on the fruit there is more or less injury on the foli- 

 age. This has been described by Stewart and Eustace as fol- 

 lows :* 



"On the upper surface the leaves were variously wrinkled 

 and puckered, but the under surface was fairly even and normal 

 in appearance except for certain areas on which the color was 

 gray green. On some trees the leaves were badly distorted with 

 the margins drawn downward and together as if they were 

 unable to unfold properly. Usually, the wrinkles were most 

 abundant along the mid-rib of the leaf and the elevated portions 

 were of a somewhat lighter green than the other parts of the 

 leaf. By cutting across the leaf with scissors it was found that 

 where the wrinkles occur the lower epidermis is separated from 

 the green, pulpy tissue (mesophyll), thus forming a large 'in- 

 terior cavity or blister. The distance between the green tissue 

 and the loosened epidermis was frequently as much as four 

 millimeters (one-sixth of an inch), and the blisters thus formed 

 were of all sizes up to those having an area of roo square milli- 

 meters or even more. In many cases the separated epidermis 

 became ruptured as if slit with a knife, leaving the cells of the 

 mesophyll exposed. Sometimes the tender cells thus exposed 

 died, causing the formation of an irregular, dead, brown spot, 

 visible on both surfaces of the leaf. However, in the majority 

 of cases the exposed cells remained green throughout the sea- 

 son." 



They ascribe this to a frost occurring about the loth of May, 

 and the appearance of the trouble first came to their attention 

 about June i. They state that in 1902 this condition was gen- 

 eral throughout New York except in the Hudson Valley and on 

 Long Island. A similar condition has appeared in Maine but 

 no such general occurrence has been observed by the writers. 

 This curling of the leaves as the result of early frosts should 

 not be confused with that caused by apple scab, aphids or plant 

 lice.f 



'^•Stewart, F. C. and Eustace, R. F. N. Y. Expt. Sta. Bui. 220, p. 218. 

 1902. 

 t vSee pp. 16 and 17 of the Circular on Apple Tree Insects of Maine. 



