UNIVERSITY OF CALIFORNIA. 
 
 AGRICULTURAL EXPERIMENT STATION. 
 
 BULLETIN NO. 18. 
 
 Mr. J. A. Bauer's Phylloxera Remedy. 
 
 As a general answer to numerous inquiries 
 concerning the probable efficacy of the phyllox- 
 era feinedy devised by Mr. J. A. Bauer, of San 
 Francisco (viz., the .ntroduction of finely 
 divided quicksilver into the earth around the 
 stock), regarding which several articles have 
 lately appeared in the public press, the follow- 
 ing points, based upon the known and observed 
 habits of the insect, are here given in advance 
 of the experiments which it is hoped will be 
 extensively made during the coming season ; 
 
 There can be no question as to the efficacy 
 of metallic mercury finely diffused through the 
 soil in killing the phylloxera or any other small 
 insect remaining within its rea<!h for any 
 length of time. Apart from the eKperience 
 long had in this respect in the means used for 
 the preservation of various articles, insect col- 
 lections, etc. , from the attacks of small inject 
 depredators, the direct experiments of Mr. 
 Bauer on earth and roots infested with the 
 phylloxera have been entirely conclusive as to 
 the inability of the latter to live more than .a 
 few hours in the atmosphere created in a close 
 space, or in earth, at the ordinary temperature, 
 by finely divided mercury. The conclusion 
 that a soil column of six or eight inches dfpth, 
 impregnated with the mercurial vapor by inter- 
 mixture with "bhie mass," will effectually pre- 
 vent the passage through it of the slow-going 
 insect, is therefore fully justified. Many other 
 substances might be used to act similarly in this 
 respect, e. g., gas lime; but none others thus far 
 suggested possess the permanency of the mer- 
 curial preparation, and the entire innocuous- 
 neps toward even the most delicate rootlets, 
 unless perhaps in the case of the direct con- 
 tact of the globules themselves. On this point 
 certninlj Mr. Bauer's inspiration has been a 
 most iiappy one, and while the introduction of 
 mercury into boreholes made in the stem of the 
 vine has long been suggested and found to be 
 useless, his suggestion is, so far as known, 
 altogether new and certainly original. 
 
 Were it feasible to impregnafe the entire 
 soil of a vineyard with the mercurial prepara- 
 tion, the phylloxera, being unable to ascend to 
 the anrface, would probably in a few genera- 
 tions be compelled to succumb, as the "win'^ed 
 forni could not then perform its functions°to- 
 ward the renewal of the tribal vigor by sexual 
 reproduction. Since, however, 30 extended a 
 
 use of ev<3n this very dilute insecticide is hardlv 
 practicable on the large scale, it remains to be 
 determiued to what extent its use immediately 
 around the trunk of the vine, in the manner pro- 
 posed by Mr. Bauer, will be likely to serve the 
 purposes of prevention and repression. 
 
 The interposition of obstacles to the passage 
 of the insect along the stock was among the 
 early suggestions of aspirants to the great prize 
 offered by the French government for the dis- 
 covery of an effectual remedy. We have among 
 the inventions aiming in that direction even a 
 propobition to encase the stock in a plaster 
 jacket of several inches thickness,. It will be 
 surmised that the sagacious insect was not long 
 in discovering a convenient path outside of the 
 lump of plaster toward the coveted roots. 
 
 In the case of Mr. Bauer's plan, however, 
 the descending or ascending insect innocently 
 crawls into a well-laid trap, which gives no 
 outward sign even by an obnoxious odor. Ac- 
 cording to the experience had thus far, it seems 
 quite likely that the unwary travelers would 
 find themselves ensnared before they had any ' 
 intimation of danger; and as there can be no 
 doubt that the great bulk of the ingress and 
 egress ordinarily takes place along the trunk of 
 the vines after the egg laid by some wanderer 
 on the leaves or branches has hatched, it can 
 hardly be doubted that a considerable re- 
 pressive influence would be exerted by Mr. 
 Bauer's remedy even where the phylloxera 
 already exists, and that it would also act as a 
 fairly effectual preventive of infection for many 
 uninfested vineyards. 
 
 Its universal efficacy is, however, limited by 
 the fact that (as has been observed in Europe, 
 and quite lately and very prominently in this 
 State) not only the winged form of the insect, 
 but even the young larval one, will ascend 
 abundantly to the surface of the ground from 
 shallow outlying rootlets, and will from thence 
 progress slowly but surely over the surface to 
 neighboring vines. Direct proofs of this fact 
 have been had here within the last few weeks, 
 and will be published in connection with other 
 new observations, in a subsequent bulletin. 
 It follows that when such shallow rootlets are 
 abundant (as they are in some soils), the 
 obstacle or trap placed along the stock may 
 affect the welfare and diffusion of the insect 
 only in a slight degree. It is still true that 
 even in this case, great numbers of the 
 wanderers will perish without reachin}{ the 
 safe harbor of a root, since most of them will 
 try the route along the stock and will there 
 succumb to the mercurial trap. Still some 
 will be likely to find their way doin 
 
I to the superficial rootlets, as the multi- 
 tude found its way np from them; and this 
 will be the more surely the case, the more 
 the soil is liable to be summer-cracked, or 
 or the coarser its tilth. In close sandy, and 
 in well-tilled soils, on the contrary, the chances 
 of stray insects descending by chance to such 
 rootlets would be exceedingly slight, in case the 
 stocks were all protected by the mercurialized 
 earth. How great is the difficulty interposed 
 to the progress of the insect on a sandy surface, 
 can only be appreciated by those who have 
 watched the ludicrous antics it exhibits under 
 such circumstances. The incessant tumblings 
 and backslidings soon exhaust its energies, and 
 show good reason why, notoiiously, the 
 phylloxera is comparatively harmless in very 
 sandy, and correlatively in very well- tilled 
 soils. 
 
 From the forej^oing considerations, those in- 
 terested may readily infer how far in their 
 particular cases the ingenious device invented 
 by Mr. Bauer is likely to prove etticacious; and 
 while still it will undoubtedly be far better 
 to plant resistant stock and graft, those favora- 
 bly situated, o»* those who have already planted 
 the non-resistant vine, will do well to take the 
 proposed remedy under careful consideration. 
 
 Examination of ,<oil from San Dv rjo pfninmla, 
 San Diego county. — This soil, samples of which 
 were furnished by Mr. Chas. Wetmore, repre- 
 sents the wider and more northcly portion of 
 the low, sandy peninsula which separates San 
 Diego bay from the ocean. It is covered with 
 thick, low brufrh, of a kind not specified, and 
 has not until lately been brought into cultiva- 
 tion. The surface soil is very finely sandy, of 
 tawny tint, beconiing more decidedly yellowish 
 as the depth increases, and fairly yellow and 
 somewhat more coarsely sandy at four feet 
 depth. When wetted it becomes but very 
 slightly coherent, and on drying *^all8 apart by 
 its own weight. The vigorous growth of chap- 
 parral upon it, however, suggests that it must 
 have some sub^tance, and this is confirmed by 
 the following analyses of samples representing 
 a tract of about 2,500 acres. 
 
 soil krom san dieoo peninsula. 
 
 Soil, 12 Ins. Subsoil, 4 Ft. 
 
 No. 795. No 796. 
 
 Insoluble Residue 88.898 ) 90.462 ) oo o 
 
 •Soluble Silica 2.432 j"^^-^'^" 2.438 "^^-^ 
 
 Potash 304 .257 
 
 Soda 117 
 
 I inie .f,09 . 370 
 
 Magnesia •. . . ,377 .317 
 
 Br. Oxide of Manganese 047 .054 
 
 Peroxide of Iron 1.975 -■ 1.916 
 
 Aluniina Z.hhh :./90 
 
 PIios; hi .ric Acid 097 .061 
 
 Sulphuri.; Avid 005 .C33 
 
 Ortranic Matter and Water. . . 1.597 1.173 
 
 Total 99.013 10O.0<i5 
 
 Iljgroscopic Moisture 1..50 3.69 
 
 Absorbed at 12° C 
 
 It is needless to aay that soils containing from 
 91 to 93 per cent of sand cannot contain high 
 percentages of plant food, as compared with 
 loam or clay soils. But the extreme pene- 
 trability of such soils by the roots renders what 
 plant food they do contain extremely available, 
 and as a matter of fact, when of considerable 
 depth, such soils are often both productive and 
 durable. 
 
 In the present case the plant food percent- 
 ages are no smaller than are found in many of 
 the soils of the southeastern States that are 
 profitably cultivated in cotton, although of 
 much less depth. Compared with these the 
 supply of potash in the San Diego soil is fair, 
 and the soda representing possibly injurious sea 
 salts, is but sparingly present. The lime sup- 
 ply for so sandy a soil is very large, ana speaks 
 of the high availability of the plant food pres- 
 ent. The supply of phosphoiic acid in the sur- 
 face soil is large for such a soil, and not defi- 
 cient even in the sandy subsoil. The whole 
 compares favorably with those soils of the Gulf 
 coast, on which sea island cotton has been suc- 
 cessfully grown for years, and which are equally 
 or even more sandy. It is therefore certain 
 to be found productive. Among fruits, the 
 olive would probably be best adapted to the 
 situation. E. W. Hilgard 
 
 Berkeley, Oct. 1, I884.