238 Bulletin 17G. 



usually attribute any success they may seem to have, not to the 

 "digging-out" process, where most of the credit usually belongs, 

 but to the other preventive applications. As our experiments show, 

 however, the application of certain preventive measures after the 

 borers have been dug out, is not a waste of energy where several 

 " old relics " are left untreated near by, or if a neighbor's peach 

 orchard a few rods away is neglected. As these conditions usually 

 prevail in the neighborhood of most peach orchards, we doubt if the 

 " digging-out " or any other method used alone, with a few possible 

 exceptions, can be depended upon to reduce the number of borers to 

 the minimum. But we believe there are several combinations of 

 this destructive method with a preventive application which will 

 give better results than either one alone in most orchards, and will 

 keep the pest under control. The best time to dig out the borers is 

 discussed in detail on p. 208. 



Preventive Measures. 



Plants. — There is little evidence to show that the odor of any 

 plant, like red cedar or tansy, will have any influence on the numbers 

 of the borers when such a plant is set with the tree (p. 212); such 

 plants would not be desirable adjuncts to peach-growing for other 

 reasons. 



Tobacco. — It has been recommended to pile or scatter various 

 substances around the base of the tree to keep out the borers (p. 212) 

 but only two of these deserve serious consideration. 



Nearly a century ago good results were reported from the use of 

 tobacco wound around the base of peach trees. We tested tobacco 

 stems (midribs of the leaves) from a cigar factory, and the results, 

 given on page 213, astonished us. Evidently the tobacco kept out 

 from two-thirds to five-sixths of the borers. We are not sure how 

 the stems acted on the insect, but our results indicate that, where 

 tobacco stems are cheaply obtainable, they will prove a good preven- 

 tive from the attacks of the peach-tree borer. 



Moundtng. — By this old and much-discussed method we appar- 

 ently keep out from one-half to seven-tenths of the borers (p. 213). 

 We do not understand just how the mounds of soil keep out the 

 borers, and we doubt if it would give as good results if not practiced 



