EFFECTS OF LOCUSTS ON TREES. 



15 



value. Each specimen should be dried, 

 weighed, and burned in a crucible, or iron 

 ladle, till nothing but sand remain; the 



loss of weight will then show how much 

 vegetable matter each parcel contained. 

 Wm. W. Valk, M. D. 



EFFECTS OF THE SEVENTEEN YEAR LOCUST ON THE ROOTS OF TREES. 



BY J. A. K., ALBANY. 



Mb. Downing — In the proceedings of the 

 Academy of Natural Sciences of Philadel- 

 phia, of Nov. and Dec, 1846, are reported 

 some remarks by Miss Morkis, in relation 

 to the larvae of the locust ( Cicada septem- 

 decim) preying upon the roots of fruit trees. 

 As relating to the article in the November 

 number of the Horticulturist, upon " Eeno- 

 vating an ' outcast ' pear tree," you may 

 deem them sufficiently interesting and im- 

 portant to lay before the readers of your 

 valuable journal. 



Before copying the remarks of Miss M., 

 allow me to make some suggestions respect- 

 ing the experiment of ' J. B. W.' detailed 

 in the number of the ' Horticulturist' refer- 

 red to. 



Cutting off a portion of the roots of an 

 old tree, in order to restore it to healthful 

 vigor and fruitfulness, may be justified by 

 reasons which I do not understand, but I 

 confess the practice appears to me quite un- 

 natural. This of course has .no reference 

 to dead or much injured roots. To ampu- 

 tate such, is reasonable enough ; but to cut 

 off all the roots, indiscriminately, at a given 

 distance from the tree, is the point except- 

 ed to. 



The rationale of ' J. B. W/s ' experi- 

 ment, as given, is, that the tree had ex- 

 hausted the proper elements from the soil, 

 in consequence of which the fruit failed. 

 These elements were restored, by the fresh 

 earth mixed with the scoriae, charcoal, and 

 potash. 



Miss Morris, as you will perceive, gives 

 another and different explanation. She 

 supposes the larvcB of the Cicada to have 

 been the real cause of disease, and in cut- 

 ting off the roots, they were removed, and 

 the trees then left free ' to take advantage 

 of the congenial soil placed around them.' 



Assuming the first, as the true cause of 

 the evil, I would suggest, that the remedy 

 was very imperfectly applied — the renova- 

 ted soil being merely presented at the ex- 

 tremities of the roots ; whereas they should 

 have been entirely uncovered and the new 

 soil covered over them. 



Also the practice of 'J. B. W.' was not 

 adapted to the larva theory. For there is 

 no reason to suppose the larvce occupied the 

 extremities of the roots any more than the 

 inner portions ; and particularly too, if Miss 

 M.'s inference be true, that ' the grubs ne- 

 ver leave the roots they first fasten on,' and 

 therefore cutting off the extremities would 

 not remove the evil. 



Nor do I think the result of the experi- 

 ment in question, affords even presumptive 

 evidence, that the plan adopted was the 

 best. Only two bushels from one tree, and 

 four from the other, the third year after the 

 remedy was applied, and that from full 

 grown trees. Now, I have faith to believe, 

 that if your excellent correspondent, ' J. B. 

 W.,' had omitted the procrustean operation 

 upon the roots, and had simply removed the 

 old soil and substituted the new, as already 

 suggested, and as his trees were probably 



