MISTLETOE INJURY TO CONIFERS. 5 



Table II. — The youngest age class of mistletoe infection on five different hosts. 



Host. 



Youngest 

 age at 

 which 

 infection 

 is kno^vn 

 to occur. 



Locality where observations 

 were made. 





Years. 

 4 

 7 

 5 

 4 

 3 

 7 

 5 

 3 

 6 

 5 

 3 

 4 

 8 



Clark Fork Valley, Mont.i 



Do 



Blue Mountains, Oreg. 



Larix occidentalis 



Priest River Valley, Idaho. 



Do 



Blue Mountains, Oreg. 



Do 



Missoula, Mont. 



Do 



Sullivan Lake, Wash. 





Spokane River, Wash. 



Do 



Blue Mountains, Oreg. 



Do 



Coeur d' Alene, Idaho. 





Spokane River, Wash. 



Do . 



Blue Mountains, Oreg. 



Do 



Coeur d' Alene, Idaho. 



Tsuga heterophylla 



Clearwater River, Idaho. 







^ Valleys o£ the so-called Bitterroot and Missoula Rivers. 



There is no reason why a seedling should not become infected 

 during its first year if seeds should happen to be favorably located 

 upon it. Seeds falling at the base of terminal buds of yellow-pine 

 branches have been known to effect an entrance in the succeeding 



./o 



.03 

 .OS 

 07 

 .06 

 OS 

 04- 

 03 

 .02 

 .O/ 









1 



L 





y 



y 































































/ 



\ 



\ 



B 

 \ 



1 



\ 





/ 



\ 













/ 



\ 

















































\ 

 \ 











s 



' 





\ 



- 



\ 





1 



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A 















































\ 



1 



















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1 





\ 







n 

 \ 







1 







































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1 



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 \ 







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I 

 \ 











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I 

 1 





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Si 















































\ 

 \ 











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1 



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 f 



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1 



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 f 



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 S 





















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_ 



























































f37^ 



/3SO 



/88S 



/S90 /S.9S 



/900 



/90S 



/S/O /3/3 



Fig. 3. — Graphs showing the average annual growth (in inches) for 40 years (1874 to 

 1913, inclusive) of 80 trees of western larch heavily infected with mistletoe, com- 

 pared with 80 uninfected trees of the same species for the same period. A, Heavily 

 infected trees : Average-age class, 144 years ; average height, 63 feet ; average diam- 

 eter, breast high, 11.5 inches. B, Uninfected trees: Average-age class, 144 years; 

 average height, 115 feet ; average diameter, breast high, 19.5 inches. 



season's growth within the year. All infections of firs and spruces 

 have been found on trees ranging from 50 to 150 years. They 

 occurred principally on the branches, resulting in large brooms, so 

 that nothing could be determined as to the probable age of the hosts 

 when infection took place. 



