70 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



4. Cracking of asphalt coat is worse with older than with the 

 younger trees. 



5. Woolly Aphis was encountered in a number of instances, es- 

 tablished beneath the asphalt coat where the tree has apparently 

 shrunken from it. 



6. It is the opinion of Professor Hewitt that asphalt injurj'^ will, in 

 some instances, be conducive to the entrance of crown gall. 



7. Injury to trees was frequent and occurred to such an extent 

 as to warrant discouraging its use altogether as a borer protector. 

 The averag-e for all asphalt treated trees was 22.9 per cent injury, 

 though it ranged as high as 40 per cent, depending on variety of tree 

 and treatment. 



8. Injury seemed to vary directly as the heat of application. Raw 

 asphalt caused 26.6 per cent injury. The 130° averaged 22.7 per cent 

 injury and the 115° mixtures averaged 7.9 per cent injury. 



9. Our data suggested that the kerosene asphaltum mixtures 

 might cause a little more injury than the other oil mixtures, though 

 this is by no means conclusive. 



10. Injury varied with the variety. For all asphalt treated trees 

 it wsis 15.1 per cent, 21.5 per cent and 25.2 per cent, respectively, for 

 Mammoth Black, Jonathan, and Yellow Transparent. 



11. Injury was of two types, (a) One type due, apparently, to 

 scalding of the bark as a result of the heat of application. It was 

 charactei'ized by killing of the bark, usually along one side, which 

 frequently induced a malformed, gaily condition, due, presumably, 

 to the attempted healing over of lulled bark by the surrounding 

 growing tissue, (b) A second type of injury appeared to have been 

 induced by interference with the normal process of respiration. It 

 was characterized by greatly enlarged lenticels, frequently accompanied 

 by excessive deposits of cork. 



12. Injury in the young trees was less the second year than the 

 first, which indicated that it was due mostlj^ to the heat of application. 



13. Injury of the second j^ear was confined to a corky type, due to 

 impairing of the process of respiration. 



14. The older trees appeared not to have been injured by scalding, 

 but seemed to be injured by the impairment of the process of res- 

 piration, as indicated by immense deposits of cork. 



15. As a protection against borers, asphalt gave protection of 82.1 

 per -cent the first year for all trees. 



16. The asphaltum combinations with oil apparently give a little 

 better protection than the raw asphalt, due, presumably, to the fact 

 that the oil mixtures were more plastic and permitted the growth of 

 the trees without cracking the asphalt coat. Raw asphalt averaged 



