LARCH MISTLETOE. 



11 



FUNGOUS ENEMIES OF THE LARCH. 



The larch on the tract examined was not attacked to any extent by 

 fungi. The fungi collected were not present in sufficient quantity nor 

 were their effects sufficiently evident to be considered the prime factor 

 in the unh^ersal deterioration of the tree. The dead wood and bark of 

 the mistletoe burls were usually infested by the larvae of Melanophila 

 drummondi Kirby (figs. 5 and 8) and occasionally were followed 

 by a fungus causing a black stain. Two burls were found infected 



Fig. 8. — Cross section of the trunk of a larch tree, showing characteristic fan-shaped 

 burl tissues resulting from an original infection when the tree was 7 years old. The 

 tree was 145 years old when cut. Note the presence of borers. (Tape in feet grad- 

 uated in twelfths.) 



with Trametes pini (Brot.) Fr. (figs. 5 and 9), but here, as in a 

 number of ether cases where fungi had entered at the burl, the hard- 

 ness and pitchy condition of the wood counteracted the advance of 

 the fungus, and it had not spread much beyond the burl tissue. It 

 is safe to state, from long field observations in other regions, that 

 mistletoe burls furnish admirable starting points for fungi; but 

 since the burl in its early stages is very pitchy (fig. 10) and the dead 

 wood becomes pronounced only after the tree is greatly injured by 

 the mistletoe itself, the effect of the fungi is to destroy later the 

 merchantability of the tree, and the mistletoe may not be the original 

 cause of its deterioration. 



