DYING OF YOUNG PINES IN CIRCLES ABOUT ANTHILLS 771 



b. Graves isolated from these areas nine species of fungi. 



c. The trouble apparently originates at a lenticel. 



On the other hand, we have the negative results of bark inoculations. 

 (The pure culture inoculation results are not available.) Hawley and 

 Record consider it as not due to a fungus, but fail to account for the 

 bark constriction. 



2. Ants are probably connected with the spread of the disease. 



a. It has not been noted except in connection with anthills ; but ant- 

 hills do occur without the damage being present. 



b. Ants do feed on the bark to a certain extent, but whether or not 

 the fungus is carried at this time is uncertain. Often gnawing is not 

 evident on af^^ected trees, and the amount observed is so slight that this 

 would seem to be a minor factor. Possibly a fungus could be carried 

 by ants bearing aphids to the tops of the trees or visiting them there, 

 though this would not explain the localization at the base of the in- 

 fected trte. Infection may be secondary, but it is to be remembered 

 that this is believed not to be the case with infestations of Fusicoccum 

 abietinmn (Hrtg.) Prill, and Del. 



3. Another factor involved is the Scolytids. These, however, are 

 apparently secondary invaders, having been observed in dead and dying 

 trees, but not in living diseased trees. 



Taking up the queries suggested on pages 3 to 4, as a whole, no defi- 

 nite answers can be given : 



1. The disease is apparently due to a specific fungus or fungi. 



2. It is doubtful that it is carried intentionally by ants. 



3. It cannot be said that the ants feed upon normal bark rather than 

 upon fungus-infested bark. 



4. 5. No memorandum has been found of ants feeding on fungi or 

 pine bark aside from the observations presented above. 



6. Possibly ants tending aphids on trees can carry the disease, though 

 on the majority of diseased trees no aphids were present. Still they 

 might have been moved after infection. 



7. Unless the Scolytids are concerned, we have no data tending to 

 show how the disease could be carried except by ants. 



8. Infection seems to be primary. It might, however, follow Scoly- 

 tid injury. 



9. There is no data on this point. 



10. The answer to this is involved in the above. 



