36 



THE LANCASTER FARMER. 



[March, 



THE POTATO'S ENEMIES. 



An Essay read before the West Grove Experi- 

 mental Farm Club, by Dr. Michener, in an- 

 swer to a referred question. 



You ask, Is it tlie white grub, or larvse of the 

 May Beetle (Lachmostura fn$cu,\ or that of 

 the False May Beetle {Lirjyrus reJictus,) which 

 often do much damage "to the potato tubers ? 

 And what preventive can be suggested for its 

 spoliations ? 



In answer, it may be the one or the other. 

 It may be both ; or it may not be either of 

 them. Of tliis I am unable to afiirm until 

 the terms of the indictment shall be settled. 

 For we must remember that the potato is 

 liable to various injuries and from various 

 enemies; and that there are other parties beside 

 May buys which possess a Hibernio- American 

 fondness for the potato. Let us then deter- 

 mine the exact offense for which these cul- 

 prits stand indicted. If I comprehend the 

 charge, it is not the ordinary eating of the 

 tubers, but a mischievous nibbling of small 

 holes over the surface, from an eighth to a 

 quarter of an inch deep, wilh a black, ragged 

 surface ; and thus rendering them both un- 

 sightly and of little worth. 



The offense must be admitted, but I fear 

 that the offenders have not been sufficiently 

 identified to warrant the conviction of these 

 grubs. Moreover, strong suspicion rests upon 

 other parties. I allude to the wire worm (Me- 

 lonotus incertus,) and to an undetermined fun- 

 gus. It is fitting that you should inquire a 

 little concerning all of these claims to villainy. 

 First. Of the cock-chafers, or the true and 

 false May beetles. These, in the larvae state, 

 are well known to be underground vegetari- 

 ans, and their ample, rotund forms show that 

 they are generous feeders. They are, more- 

 over, to be found in those soils wherein the 

 potato delights to grow. I presume that they 

 are too mudi like ourselves to be willing to 

 starve in the midst of plenty, without making 

 an appropriation of a part of the crop to their 

 own use. This they no doubt do; but they do 

 it boldly, and as of their right to do it. There 

 is no thievish pilfering, nibbling a little here 

 and a little there. They go right into the job, 

 and can often be found at their work neatly 

 ensconced in the excavations which they have 

 eaten in the tubers. But I am utterly unable 

 to co-ordinate these larvfe with the injury of 

 the potato specified in the indictment, and 

 therefore must refer the question back to the 

 Moot Court for your further investigation. 



Second. Of the vnre worm, or larvae of the 

 click-beetle. Here I must reproduce the testi- 

 mony of our esteemed fellow member, W. R. 

 Shelmire, and the comments of the excellent 

 editors of the ^■l77i<^7-ico)i Entomologist (see Vol. 

 II, p. (32.) But without having the advan- 

 tage of a cross-examination of the witness, I 

 fear that I may not fully comprehend and duly 

 appreciate his testimony. As I understand 

 him, he charges the icire loorm with injuries 

 which the indictment does not exactly cover; 

 viz: that it eats its way, and enters right into 

 the tuber, where it not only finds an ample 

 supply of sweet, palatable food, but that it be- 

 comes domiciled therein during the winter, 

 ready to be returned to the soil at the plant- 

 ing season, to renew its annual round of plea- 

 sure and of destruction; for you must know 

 that both the white grubs and the icire ivorms 

 continue several years in the larval state. I 

 infer this to be the tenor of the bill which our 

 witness has filed, from the editorial remarks 

 above referred to, and from which I will read: 

 "W. R. Shelmire, Tough Kenamon, Pa.— 

 The elongate, cylindrical, horny, mahogany- 

 colored worms, nearly an inch long, that bored 

 up so badly your crop of Mercer potatoes, are 

 a very common species of wire worm. This 

 particular kind produces a click beetle (Melo- 

 notus incertus.) There are a few that devour 

 living vegetable matter, and are great pests 

 to the farmer. We have known them to de- 

 stroy the young corn plants to a grievous ex- 

 tent, gnawing laterally into the stem, just un- 

 der the surface of the ground. 



"Your neighbor is right in saying that if 



you plant these worm-eaten potatoes they will 

 produce wormy potatoes ; that is, if you plant 

 potatoes with the wire worm in them, for these 

 wire icorms live several years in the larvee 

 state, and having six good legs of their own, 

 they would readily migrate from the infected 

 potato sets to tlie growing potatoes. You 

 must not suppose, however, that tcire ivorms 

 can breed ivire icorms, for it is not until after 

 the larvaj has developed into the click beetle 

 that it becomes capable of propagating its 

 species. There are, no doubt, plenty of them 

 remaining in your late potato ground. Sow- 

 ing six bushels of salt to the acre, is said by 

 one of the best farmers in England— Alder- 

 man Mechi — to destroy all the ivire worms in 

 the salted ground. We know of no mode but 

 hand-picking to destroy the wire vxirms in 

 your potatoes so that they can be used for 

 seed." 



This enemy of the potato, from his small 

 size, and of a color simulating that of the soil 

 he inhabits, is far less conspicuous than the 

 May beetle larvse, and may be more easily 

 overlooked ; but he does not appear to have 

 the habit of nibbling on the surface, as 

 the bill charges. He bolts right in just 

 as his and our Creator designed that he 

 should do, and, as I have said, authorita- 

 tively ai)propriates the whole tuber to the 

 double purpose of affording an abundant sup- 

 ply of choice food and a comfortable domicile 

 for the long and dreary winter season, with a 

 coach-and-six to carry him back to the field 

 on the return of spring. 



Here, as in the previous case, whatever or 

 however great his offense may be, I think 

 that you must exonerate him from the spe- 

 cific injury mentioned in the bill. 



Third. "The last culprit that I shall arraign 

 before you is the Fungus, alias whatever you 

 may please to call him, for he has thus far 

 withheld his name. He stands accused of 

 the very mischief we have been considering. 

 The evidence may all be circumstantial, but 

 this is a necessity of the case, for, as the law 

 is, no jury can receive strictly positive testi- 

 mony in any case. I must, therefore crave 

 your attention to the following views : 



When potatoes are eaten by larvae, as in the 

 preceding cases, and the injury is recent, we 

 find the flesh of the tuber fresh, white, 

 smooth, and inclining to heal or skin over, as 

 we observe it do when cut with a knife ; yet 

 who has ever seen such an appearance in the 

 disease before us ? I have not ; no, never. I 

 have sought for it again and again, but with- 

 out success. On the contrary, whenever and 

 wherever I have seen the injury which we are 

 considering, from the smallest speck up to the 

 more extensive destruction of the organic tis- 

 sue, the appearance has constantly been the 

 same. Its features denote its parentage. Its 

 dark complexion, its sunken visage, its ragged 

 dress, its erratic habit, all indicate a per- 

 nicious disease, reminding one of those gan- 

 grenous and destructive ulcers so often seen in 

 crowded and ill-ventilated hospitals, and simi- 

 lar places, from the action of morbific spores, 

 which empoison their atmosphere. Indeed, 

 the aspect is similar, the parallel so complete, 

 as to strongly suggest a consimilar origin. 



It appears to be "admitted that if we plant 

 diseased tubers we may expect to grow diseased 

 potatoes, even where "there are no wire worms 

 present. Such as men sow, such shall they 

 reap. If the disease were a mere bite, I would 

 ask how could that bite be propagated, and, if 

 so, how can we expect to raise whole potatoes 

 when we only plant pieces ? To me it seems 

 that there is a si>ecific diseased action produced 

 in the tuber by whatever cause, which is capa- 

 ble of producing the same kind of action in the 

 new potato, either through the tissues of the 

 plant or through the soil. 



Again, it has been pretty fully ascertained 

 that there is something lefX remaining in the 

 soil where diseased roots have been grown that 

 is capable of affecting healthy potatoes planted 

 therein the following year in a similar manner. 

 I once planted selected potat(jes in the same 

 ground for four successive years. The number 

 of diseased tubers rapidly increased from year 



to year, until the last year half the crop was 

 destroyed. 



An intelligent and observant friend of mine 

 planted a few rows of potatoes across his lot. 

 They proved to be a good deal injured. The 

 next jear he planted the same ground, with a 

 corresponding strip alongside, which had been 

 cultivated in some other sort of crop the pre- 

 ceding year. The result was, the crop in the 

 old potato ground was almost worthless, while 

 that in the contiguous portion was only slightly 

 affected. All the conditions of soil, culture, 

 manure and seed were similar. 



We know that insect depredators do often 

 manifest wonderful discriminating powers in 

 the selection of their food. But the Fungi, 

 which constitute a still more predaceous class, 

 are in a much greater ratio selective in the 

 choice of their food, as well as in the places for 

 their nidiflcation. They are, indeed, so numer- 

 ous and so discriminating that almost every 

 plant appears to have some specific fungoid 

 growth peculiar to itself. 



The thing under discussion may yet prove 

 itself to be a Fungus peculiar to the potato, and 

 not to be found anywhere else. 



The ultimate appeal must probably be made 

 to the higher powers of the microscope to de- 

 termine the essential nature of this obscure 

 and mysterious affection. 



So long as the cause and nature of the mis- 

 chief is unknown, so long its prophylactic and 

 remedial treatment will be empirical and un- 

 satisfactory. But let us not despair. What- 

 ever hypothesis we may adopt, it ought to sug- 

 gest something as wortliy of trial. 



From what has been already said it may be 

 of the utmost importance to plant none but 

 the most perfect and clear tubers, and to avoid 

 rei)lanting the old potato grounds. 



It may also be prudent not to plant those 

 varieties which have been found most obnox- 

 ious to the disease. 



If the germs inhere in, and are liable to be 

 planted with, the potato, and I think tliat is 

 the correct view, it would seem to suggest the 

 use of some means for disinfection of the seed 

 before plantijig. 



For this purpose I would recommend the 

 trial of a solution of carbolic acid in water, of 

 such strength as the tubers will bear without 

 injury. The proper strength can only be as- 

 certained by careful trials. Thus : Take car- 

 bolic acid — an ounce ; water — a gallon ; mix 

 when ready to plant ; immerse the setts in the 

 solution for five minutes ; then remove and 

 rinse the acid off before planting. 



As the Fungi are mostly found in connection 

 withdiseased, ordead and decomposing organic 

 substances, from which they may sometimes 

 pass over to healthy, living organisms, it may 

 be a question worthy of your consideration : 

 How far the fertilizers used, may have aided in 

 the productionofthedisea.se? To what extent 

 was it known before their introduction ? And 

 how far has it been increased under this use V 

 The complexity of the subject, and the extent 

 of the traverse must be my apology for the pro- 

 lixity of my answer. 



SUPPLEMENTARY. 



Wearisome as this extended report may be, 

 the end is not j'et. After it was written, it oc- 

 curred to me tosend a specimen of the diseased 

 potato to my excellent friend Dr. Gibbons Hunt, 

 one of the most profound observers and expert 

 microscopists in Philadel])hia, for his examina- 

 tion ; remarking at the time, " That the my- 

 celium, and stroma of the fungus could better, 

 and perhaps only, be observed in the earlier, 

 and growing state of the plant." 



I will now read you his report : 



Philadelphia, 13th mo. 17, 1875. 



Dr. Michener — ^^y Respected Friend : Thy note 

 of the 15th inst., and also the potato, came duly to 

 me. I have felt an interest in the subject of the dis- 

 eases of the potato, and therefore have taken some 

 pains to examine the afflicted tuber thee sent me. A 

 superficial or external examination of the diseased 

 spots, under a lens, magnifying from thirty to fifty 

 diameters, reveals but little that is intelligible. A 

 number of dark, opaque pellets, which I interpi-et to 

 be the alimentary exuvia of some larva, readily 

 came into view. I consider them to be of that char- 

 iicter, because, when put into water, under a micro- 

 scope, and submitted to pressure, they easily dislnte- 



