A DISEASE OF SYCAMORE TREES. 213 



effects of crop rotation may be exj)lained equally well from the 

 standpoint of the Liebig theory or of this newer one, and this 

 may explain why the phenomena of toxic excretions have so long 

 escaped serious consideration. It appears that the Liebig theory 

 has been jDushed rather farther than necessary, but how far it is 

 to be supplemented or replaced by the new conception is at pres- 

 ent only a matter of conjecture. There are enthusiasts on both 

 sides of the argument. W. E. McC. 



A DISEASE OF SYCAMOKE TREES. 



Sycamore trees {Platanus occidentalis) are suffering from 

 a fungus or a cold spring season in parts of N^ew Jersey and in 

 eastern Pennsylvania. The early leaves are shriveled and dark 

 in color and the trees appear dead excepting for a few green tips. 

 The farmers attribute it to the cold spring. The fruit buds have 

 escaped in many instances. Out of about seven hundred trees 

 observed in the region mentioned, less than fifty have escaped 

 marked injury, the rest having lost at least three-fourths of their 

 leaves. Those which have suffered least are those under thirty 

 feet in heiolit and e'rowino; in sheltered locations. 



If a fungus is responsible for the appearance of these trees, 

 the question arises, why does not isolation play a more important 

 part ? I know of no single tall tree which has escaped almost 

 complete defoliation. Would the action of a fungus account for 

 the fact that in the least injured trees the lower branches (which 

 are most protected from the cold) have all suffered somewhat ? 



JEAls^ BROADIIITRST. 



TliP diseased eonddion referred to in the above note is due 

 to a fungus, "the active vegetative portion of wdiich lives within 

 the leaves and twigs ; the fruiting portion appearing in brown 

 patches on the twigs or veins of leaves that have been killed. The 

 effects of the fungus are usually not lasting except in the case of 

 trees already weakened by disease or starvation." (W. A. Mur- 

 rill, in Jour. X. Y. Bot. Garden, July, 1907.) The fungus is 

 Gloeosporium nerviseqnum Sacc. according to Murrill. 



F. E. L. 



