20 



BULLETIN 1112, U. S. DEPARTMENT OF AGEICULTUKE. 



EFFECT ON THE FOLIAGE. 



Tables 14, 15, and 16 show the effects of the mistletoe on the foliage 

 of the western yellow pine. The data included in Table 16 were 

 obtained as follows : 



Each tree crown was divided into three divisions — bottom, middle, 

 and top — including in each division about one-third of the total leaf 

 surface. One hundred tufts from each section were selected at ran- 

 dom and measured ; the mean length of these tufts was taken as the 

 average length per tuft for that section. Then 10 tufts of this 

 average length were taken from each of the three sections into which 

 the crown had been divided. These tufts, 30 in all for each tree, were 

 cut off and taken to the laboratory, where the number of leaves per 

 tuft, the length, and the width of each leaf were determined. The 

 total number of tufts in the bottom, middle, and top thirds was 

 determined by actual count. The number of tufts thus obtained was 

 multiplied by the average number of leaves found in the 10 tufts 

 from each section. This gave the average number of leaves in each 

 section. The sum of the leaves in the three sections gave the average 

 number o:^ leaves in any given tree crown. 



Table 14. — Comvarison of the length of leaves of 103 western yellow pine trees, classified 

 according to degree of mistletoe infection. 



Degree of 

 infection. 



In lower portion 

 of crown. 



In central portion 

 of crown. 



In upper portion 

 of crown. 



Mean for entire 

 crown. 





Mean 

 mini- 

 mum. 



Mean 

 Maxi- 

 mum. 



Aver- 

 age. 



Mean 

 mini- 

 mum. 



Mean 

 maxi- 

 mum. 



Aver- 

 age. 



Mean 

 mini- 

 mum. 



Mean 

 maxi- 

 mum. 



Aver- 

 age. 



Mean 

 mini- 

 mum. 



Mean 

 maxi- 

 mum. 



Aver- 

 age. 



Basis. 







X 



XX 



XXX 



In. 

 3.3 

 2.3 

 2.1 

 2.1 



In. 

 6.2 

 5.3 

 5.3 

 5.1 



771. 



4.9 

 4.0 

 3.8 

 3.6 



In. 

 3.8 

 2.5 

 2.5 

 2.4 



In. 

 6.3 

 5.9 

 5.4 

 5.1 



In. 

 5.5 

 4.5 

 4.1 

 4.0 



In. 

 4.2 

 3.3 

 2.9 

 2.7 



In. 

 6.9 

 6.2 

 6.7 

 5.1 



In. 

 5.8 

 5.0 

 4.6 

 4.0 



In. 

 3.8 

 2.7 

 2.5 

 2.4 



In. 

 6.5 

 5.8 

 5.5 

 5.1 



In. 



5.4 

 4.5 

 4.2 

 3.9 



Trees. 

 38 

 15 

 18 

 32 



Table 15. — Comparison of the length of leaf tufts of 97 western yellow pine trees, classified 

 according to degree of mistletoe infection. 



Degree of 

 infection. 



In lower portion 

 of crown. 



In central portion 

 of crown. 



In upper portion 

 of crown. 



Mean for entire 

 crown. 





Mean 

 mini- 

 mum. 



Mean 

 Maxi- 

 mum. 



Aver- 

 age. 



Mean 

 mini- 

 mum. 



Mean 

 maxi- 

 mum. 



Aver- 

 age. 



Mean 

 mini- 

 mum. 



Mean 

 maxi- 

 mum. 



Aver- 

 age. 



Mean 

 mini- 

 mum. 



Mean 

 maxi- 

 mum. 



Aver- 

 age. 



I7l. 



10.2 

 8.3 



5.S 

 4.8 



Basis. 







X 



XX 



XXX 



In. 

 3.4 

 3.0 

 2.4 

 2.3 



In. 



11.5 



10.1 



8.2 

 8.1 



In. 

 6.7 

 6.5 

 4.9 

 4.5 



In. 

 5.4 

 4.0 

 2.3 

 2.6 



In. 

 15.5 

 12.0 

 9.1 

 8.6 



In. 



10.0 

 8.0 

 5.2 

 5.0 



In. 

 6.8 

 5.5 

 3.4 

 2.4 



In. 

 22.7 

 16.8 

 11.1 



8.5 



In. 

 13.8 

 10.3 

 7.3 



4.8 



I7l. 



5.2 

 4.2 

 2.7 

 2.4 



Iv. 

 16.6 

 13.0 

 9.4 



8.4 



Trees. 

 37 

 15 

 15 

 30 



