114 CANKER-WORM. 



For this purpose, the following experiments were performed : 



On the 30th of March, before the buds had expanded, I selected 

 two thrifty, five-year old apple trees and anointed them all over, twigs 

 and all, with kerosene oil. 



On May 9th, after the foilage had expanded, I anointed the trunk 

 and large branches of another tree, leaving the smaller branches and 

 foilage untouched. 



On the 13th of May, with the view of making the test more general, 

 I scraped oflf the rough outer bark from the trunks of a number of for- 

 est trees, three or four inches in diameter, for a space of about two 

 feet, and thoroughly anointed them with kerosene. The trees experi- 

 mented with were a white oak, a hickory, an iron wood, a thorn, and a 

 crab apple. I examined these trees at various times in the summer and 

 fall, and could not find that any permanent injury had been inflicted 

 upon them. In the case of the two young apple trees which weie 

 anointed all over, the^first crop of buds were either killed or checked 

 in their development, and these trees were several weeks later than 

 others in leafing out. But later in the season (July 6th) these trees 

 appeared as healthy and their foliage as full as any others. 



In connection with these experiments, similar ones were made with 

 simply greasy substances, such as lard and linseed oil, with equally 

 harmless results. 



The application of coal tar to the trunks of young trees, however, 

 has resulted much more disastrously. Mr. Jonathan Sells, of Bloom- 

 ington, imformed me that having seen it stated in an agricultural pa- 

 per that the application of coal tar to the trunks of apple trees would 

 keep ofi' rabbits, he applied it to a space of six or eight inches high, at 

 the bottom of the trunks of sixty apple trees, six years old from the 

 graft, and every tree was killed and subsequently dug up. 



How can we explain the difierence in these two results ? Was it 

 that the coal tar is so much the more powerful and injurious in its ef- 

 fects, or was it due to the diiference in the time of the year when the 

 applications were made ? 



1 wrote with reference to this point to my friend, Mr. Tinker, whose 

 large experience in these matters renders his opinion of much value, 

 and in his reply, under date of September 12, he says: "I have seen 

 young trees injured by coal tar, put on in the winter to keep ofi" rab- 

 bits, but I think any thing will injure a tree more, put on when thesao 

 is dormant, than when growing." He adds that he has found pine 



