34 MAINE AGRICULTURAL KXPERIM^NT STATION. 191I. 



On the apple and pear the injuries have manifested them- 

 selves in two ways, — burning and spotting of the leaves and 

 russeting or "corking" of the fruit. 



The leaves so affected show dead brown spots, similar in gen- 

 eral appearance to some leaf spots produced by fungi and espec- 

 ially to those of the fungus causing black rot and canker of 

 pomaceous fruits (Sphaeropsis malorum, Pk.). These spray 

 injury spots are generally circular or roundish, though often 

 irregular. Frequently the areas are large, as if a number of 

 smaller ones had coalesced. Occasionally the margins of the 

 leaves show the characteristic dark brown or blackened dead 

 tissues (Fig. 47). 



Such foliage injury is very frequently followed later in the 

 season by yellowing and premature leaf fall. This occurs early 

 or late according to the severity of the injury; in some seasons 

 it is absent. That this phenomenon is the direct result of using 

 bordeaux mixture or other sprays has not been fully proved, 

 but the frequency with which it accompanies spray injury tends 

 to establish a correlation between them.* 



On the fruit the injury is first seen as small, dark, fly-speck 

 like spots. These are not to be confused with infections of the 

 scab fungus (Venturia Pomi (Fr.) Wint.) or with the fly speck 

 ■fungus (Leptothyrium Pomi (Mont, and Fr.) Sacc). The for- 

 mer are regular, smaller, — about one millimeter diameter, — and 

 not sunken. The final appearance of the fruit is well known 

 to nearly all orchardists with experience in spraying. The 

 skin is washed or splashed with a rusty or russet colored coat- 

 ing which materially detracts from its appearance. In very 

 mild cases of injury fruit of a naturally good color may, it is 

 said, practically overcome a slight russeting as the season de- 

 velops. Such instances have been reported in this State this 

 year. In more severe cases the apple has been stunted in 

 growth and has suffered malformation, while the russeted sur- 



* Mr. F. C. Stewart also reports spotting and yellowing of leaves 

 following the use of an arsenical without bordeaux. "Two Unusual 

 Troubles of Apple Foliage." New York Agric. Exp. Sta. (Geneva). Bul- 

 letin 220, Part II, p. 226. 



Woodworth and Colby also ascribe leaf yellowing and early leaf fall 

 to injury from Paris green. California Agric. Expt. Sta. Bulletin 126, 

 p. II. (1899). 



