268 
Journal of Agricultural Research. 
Vol. XXXI, No. 3 
Girdling, an old and common method, consists of so severing the 
cambium and phloem of the tree that the nutritive communication 
between root and crown is permanently interrupted. 
EARLY ATTEMPTS AT KILLING BY GIRDLING 
As far as known to the writers, the first attempt, apart from 
general broadcast burning, for the specific purpose of destroying 
undesirable white fir and hemlock on Forest Service sales, was in 
1910, on the Kaniksu National Forest. Here the hemlock and 
white fir were girdled in three seed plots, a belt of bark 2 to 3 feet 
high around the base of the tree being stripped off. The work was 
not done carefully and many strips of inner bark were left intact, 
connecting the root and the top. Consequently very few of the trees 
were killed and the wounded portion is gradually healing by the 
growth of new bark. 
The objects of the girdling—to prevent seed production on the 
adjoining clean-cut area, and to lessen the shade in the seed plot— 
were both defeated, as the girdled trees produced heavy seed crops 
three years later, and the shade in the plots was not materially 
decreased. 
The next work of the kind was on several cuttings in the white- 
pine type on the Coeur d’Alene National Forest, which was followed 
the next year by additional girdling on later sales. The method 
has since been specified for use in all white pine sales on the Coeur 
d’Alene Forest. 
Two different forms of girdling were employed in these early trials. 
One was to strip off the bark around the base of the tree for a width of 
2 to 3 feet, a method similar to that used on the Kaniksu National 
Forest. The other was to cut a notch 1 to 2 inches deep com¬ 
pletely around the tree, with or without some stripping of the bark 
above or below the notch. 
The stripping method was tried in the winter when the bark 
adhered so tightly that it would not peel but had to be cut off. The 
leaving of narrow strips of inner bark connecting the upper and 
lower ends of the wounds was, in many cases, unavoidable. The 
following year it was noticed that many of the hemlock and white 
fir trees which had been girdled by the notch or stripping methods 
still had green healthy tops and were bearing unusually heavy 
crops of cones. In order to determine whether the girdling had 
affected the fertility of these cones, two large hemlocks, one girdled 
by stripping and the other by notching, were cut, and a bushel of 
cones collected from .each. Seed was extracted at the Northern 
Rocky Mountain Forest Experiment Station at room temperatures, 
never higher than 80° or 90° F., and duplicate tests of 500 seed each 
were made in sand flats in the experiment station greenhouse. The 
results are given in Table I. 
