BULLETIN 1112, U. S. DEPARTMENT OF AGKICULTUEE. 



classes might be explained by the fact that of the 27 trees in the 

 infection class, 11 per cent were isolated trees which did not form a 

 part of the forest canopy, 28 per cent were dominant, 57 per cent 

 were codominant, and 4 per cent were intermediate trees, whUe 

 with the X infection class 60 per cent were isolated trees which did 

 not form a part of the forest canopy and 40 per cent were in the 

 codominant crown class. Table 2 consistently shows a decrease in 

 the rate of diameter growth of yellow pine which varies directly 

 with the degree of mistletoe infection. 



Table 1. — Comparison of the average diameter growth or accretion of 58 standing black 

 jacks, for a 5-year period, grouped according to degree of mistletoe infection. 



' 



Diameter breast-lilgh. 



Accretion, 1910-1915. 





Degree of infection. 



1910 



1915 



Periodic. 



Periodic 

 Annual. 



Basis. 





Inches. 

 16.16 

 17.65 

 15.82 

 14.24 



Inches. 

 16.97 

 18.63 

 16.57 

 14.36 



Inches. 



0.81 



.98 



.75 



.12 



Inch. 



0.16 



.20 



.15 



.02 



Trees. 



27 



X. , 



6 



XX 



15 



XXX 



10 







Table 2. — Comparison of the average diameter growth or accretion of 33 standing yellow 

 pines, for a 5-year period, grouped according to degree of mistletoe infection. 





Diameter breast-high. 



Accretion, 1910-1915. 





Degree of infection. 



1910 



1915 



Periodic. 



Periodic 

 annual. 



Basis. 







Inches. 

 24.60 

 25.56 

 22.14 

 21.49 



Inches. 

 25.30 

 26.04 

 22.44 

 21.61 



Inch. 



0.70 



.48 



.30 



.12 



Inch. 



0.14 



.10 



.06 



.02 



Trees. 



9 



X 



8 



XX 



7 



XXX 



19 







1 Five trees of this class died during the 5-year period and were not included in the computation. 



Table 3. — Comparison of total volume groivth or increment of 58 standing black jacks, 

 for a 5-year period, grouped according to degree of mistletoe infection. 



Degree of infection. 



Total volume. 



Increment, 1910-1915. 



Basis. _ 



1910 



1915 



Periodic. 



Periodic annual. 







Cubic feet. 

 987.2 

 291.4 

 434.0 

 234.9 



Cubic feet. 



1, 100. 9 



324.4 



470.6 



243.2 



Cubic feet. 



113.7 



33.0 



36.6 



8.3 



Cubic feet. 



22.7 



6.6 



7.3 



1.7 



Per cent. 



2.30 



2.26 



1.68 



.72 



Trees. 



27 



X 



6 



XX 



15 



XXX 



10 







