Feb. i 9 , i9i7 Arsenical Injury through the Bark of Fruit Trees 
297 
RELATIVE INJURY TO BRANCHES OF DIFFERENT SIZES 
As it was difficult to find enough branches of exactly the same size to 
carry on this entire investigation and as there is some purely scientific 
interest in knowing whether smaller branches are more or less susceptible 
than larger ones, especially through the lenticels, a series of tests was 
made on limbs and branches of as widely varying sizes as could be found 
without including any having rough bark. 
Twelve unwounded branches were treated with 10 gm. each of Baker's 
calcium arsenite. These varied in size from % inch to 2% inches. Of the 
three that were only % inch in diameter, two were killed above the band¬ 
age, and the other was nearly girdled under the bandage but uninjured 
above and below. The rest all showed anastomosing lenticel spots. On 
the branches less than 1 inch in diameter the enlargement of these spots 
had resulted in a complete girdling, and in some cases in streaks several 
inches long. On the larger branches, of which there were six, the spots 
were a little more distinct and about alike on all, with no streak above or 
below the bandage. 
If, then, the branches are unwounded, we find that in those between % 
inch and 1 inch in diameter there is no consistent difference in suscepti¬ 
bility dependent upon size. There is sometimes found a considerable 
variation on smaller-sized branches even on the same tree; but, between 
the limits just named, size seems to be an unimportant factor. Unless 
otherwise specified, the branches described in the tables of this paper 
were from $/% to inch in diameter. Branches as small as % inch in diame¬ 
ter appear to be worse injured. Branches more than an inch in diameter 
show less streaking than the smaller ones, though the lenticels absorb the 
arsenicals almost as freely. The thickness of the bark seems to be a 
factor here. Except for the fact that the branches are eventually killed 
by girdling under the bandage through anastomosing lenticel spots, the 
injury does not extend as far from the bandages as in the smaller 
branches. 
Twelve other branches varying in size from % inch to 2% inches were 
wounded by cutting off a small twig or by cutting a small notch to the 
cambium. Each was then treated with 10'gm. of Baker's calcium 
arsenite. The injury to these limbs was very severe. All less than 1 
inch in diameter were killed above the bandage and there were long 
streaks below. Those more than 1 inch across (except one) were badly 
injured above the bandage but not entirely killed, and the streaks below 
were much shorter than on the smaller branches. The one exception 
just mentioned, which was i l /i inches in diameter, was the worst injured 
of any. It was killed above the bandage and a wide dead streak ran 
down 4 feet to the trunk and out a large side branch 6 feet to its tip. 
It would seem from this that, when branches have been wounded so as 
to expose both phloem and xylem ducts, there is no consistent difference 
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