9 



be removed very early in order to avoid the danger from 

 heart rot fungus. It should be remembered, however, that the 

 cambium is even more resistant than the bark and may remain 

 alive when both bark and sapwood have been badly killed. In 

 that case a new layer of bark will be formed under this old 

 dead bark if it is not removed. If it is removed, the cambium 

 is likely to be dried out and to die. In our observation in a 

 large percentage of cases the cambium was alive and new bark 

 did form if the old bark was not removed. In practically all 

 cases the cambium was alive at least around the edges of the 

 wound under the dead bark, so leaving the dead bark in prac- 

 tically all cases markedly reduced the size of the wound. 

 When it is considered how slowly these wounds heal and how 

 important it is for the strength of the branch that they be 

 healed, the benefit from leaving this old bark for one summer 

 will be appreciated. It would seem best, then, to delay remov- 

 ing this old bark until the second summer after the trees have 

 been injured, and if there is an area left where the sapwood is 

 exposed to paint that. It seems best, also, to do the same with 

 the dead bark on the trunk. 



So far as sapwood killing or complete killing was concerned 

 the most tender variety of apples was the Baldwin. Tompkins 

 King, Rhode Island Greening, Gravenstein, bearing Hubbard- 

 ston, Stayman Winesap and Esopus were nearly as tender. 

 Ben Davis was more resistant, but it suffered great injury. Xo 

 injury was found in New York- State to either Mcintosh or 

 Oldenburg, and Delicious seemed very resistant. Both Fameuse 

 and Wealthy proved less resistant than Mcintosh, and North- 

 ern Spy was decidedly less resistant. 



It should be borne in mind that the killing during the winter 

 of 1917-18 was not determined entirely by the winter. The 

 previous summer was exceedingly short and the wood was not 

 well ripened for winter. Anything that reduced the foliage 

 during the previous summer generally increased the amount of 

 injury; thus, in an average year, the loss of foliage of late 

 summer due to the red hump apple worm has not been consid- 

 ered serious. However, I do not know of a single case where a 

 tree or branch was not killed where the foliage had been re- 

 moved in this way during the summer of 1917. I saw instances 



