ICG Report of the Botanist of the 



If the injury is severe and occurs before the leaves are fully 

 grown,^ the injured leaves fall and new ones appear, but if the 

 injury occurs after the leaves are full grown they remain attached 

 to the twigs until late in autumn. In the latter case some of the 

 leaves vdW be found wholly dead, but the majority of them will 

 show a dead, bro^vn portion and a living, green portion. As a 

 rule, especially on the sugar maple, the dead portion is located 

 around the margin of the leaf (see Plate IX, fig. A), but it may 

 occur in the form of circular or irregular blotches; or the margin 

 of the leaf may be occupied by living, green tissue surrounding a 

 dead area at the center (see Plate IX, fig. B). In all cases the 

 living tissue is separated from the dead by a sharply defined line. 

 The color of the dead tissue is either light bro^vn or reddish brown. 

 The injured leaves for the most part remain expanded. 



As with the beet, cherry and cauliflower, this injury to maple 

 foliage occurs in a comparatively short space of time. It happens 

 whenever the quantity of water transpired by the leaves is greater 

 than that which the roots are able to supply; and this condition of 

 things may be brought about in several ways. Some of the 

 factors which enter into the problem are: Area of leaf surface 

 exposed, quantity of water in the soil, activity of the roots, and 

 location of the tree as regards exposure to T\dnd. Having in mind 

 these several factors, it is easy to understand how one tree may 

 be seriously injured while another tree standing close beside it 

 may not be affected at all. This is of common occurrence. 



In nurseries the disease often escapes notice until the dead 

 leaves have become overgrown with various saprophytic fungi 

 which are likely to be mistaken for the cause of the trouble. 



Trees recently transplanted may die from the effects of leaf 

 scorch, but established trees rarely show any permanent injury. 



8 Observations iipon the scorching of immature maple foliage have been re- 

 ported by Stone, G. E., and Smith, R. E. Wilt of Maple Leaves. Ninth Ann. 

 Kept. Hatch Exp. Sta., of Mass. Agr. Coll.: 81-82; also by Stewart, F. C. 

 Norway Maples Injured by Dry Winds. Fifteenth Ann. Eept. of this Station: 

 453-454. 



