New YorK AGRICULTURAL EXPERIMENT STATION. 245 
BLISTER MITE INJURY. 
In Bulletin No. 283 of this Station, P. J. Parrott, Station En- 
tomologist, speaks of the confusion of mite injury with bordeaux 
injury and clearly indicates the distinction between the two: 
“Injuries by the mite and by spraying mixtures, often appear 
upon the same leaf and have been much confused. ‘The two are 
quite distinct and may be easily distinguished. Injuries due to 
treatment by the bordeaux-arsenical mixtures appear as dead 
brown spots of various sizes and shapes, and are irregularly dis- 
tributed over the leaf surface. Frequently these spots are round- 
ish or circular with a diameter of one-twelfth to one-eighth of an 
inch, while others are irregular in outline and much larger. A\l- 
though the line of demarcation between the dead and living 
tissue is sharp, these spots are to the touch flat, often depressed, 
-and are not in this manner distinguishable from the general sur- 
face of the leaf as are the mite-blisters. Spray-injured spots show 
the venation of the leaf which is seldom apparent in the mite 
galls, and the dead areas also lack the small hole leading to the 
interior, which is always present in the corky spots produced by 
mites.” 
INJURY FROM THE LENS ACTION OF DROPS OF WATER AND BRIGH?P 
SUNSHINE. 
Beyond question the lens action of drops of water on leaves 
in bright sunshine may injure them. The drops of water act as 
lenses and concentrate the sun’s rays so as to burn the tissues 
beneath. Schander*t says that Von den Planitz places the re- 
sponsibility of the cork-like russeting of the fruit on this agency. 
He also says that injurious action may be observed at times on 
the leaves when sprayed in too strong sunlight. Duggar® gives 
an account of a case in which bright sunshine following rain 
caused the appearance of “shot-holes” in peach leaves. Such 
lens action of drops of water in sunshine is not uncommon in 
greenhouses and serious damage often results in this way. In 
an orchard, such injury might follow a burst of sunshine either 
after spraying or after a shower. 
An attempt was made to investigate lens action as a possible 
cause of fruit-russeting and leaf-dropping in connection with the 
work of this experiment, but the results were not such as to lead 
**Schander (53, p. 578). 
* Duggar (18, p. 388). 
