November i, 1883.] THE TROPICAL AGRICULTURIST. 



403 



MR. STORCK'S CURE FOR COFFEE DISEASE. 

 Upper Rewa, July 4th, 1882. 



De.ur Sir, — Since I, a twelvemonth ago, established 

 the first experiment with my " method of permanent 

 vaporization," I have learned agi-eat deal on the subject, 

 and will now give you a summary of ray experiences 

 and the final results of the treatment. An account 

 of the first stage of my experiments has ah'eady ap- 

 peared in print, and I, therefore, proceed with a 

 sketch of what followed. 



With the low density of the fluid mixture and its 

 vapors I attained certain I'esults which drew my attention 

 forcibly to the Influence of the vaporized atmosphere up- 

 on the mycdia of both tho already rust-bearing spots 

 and those still in formation within the tissue of the 

 leaves. Altliough vast numbers of the spores perished in 

 the act of germination, I could not shut my eyes to tlie 

 fact that a small j'roportion escaped, as proved by 

 the reapjjearance of pinspots on new foliage. Of 

 these pinspots many again died under the treatment, 

 but the survivors gi-ew laterally, were gi-eenish yellow 

 in colour, owing to the comparatively large areas of 

 live green tissue among the branches of the mycelia, 

 as seen under the microscope. They grew and changed 

 theu' appearance very slowly, seldom produced healthy 

 spores, and generally perished with the leaf without 

 producing any. Leaves so afl'ected would live for many 

 months. Several occasions, however, when the treat- 

 ment was purposely interrupted, and the density of 

 the fluid and vapor sank below a certain level, those 

 inert-looking spots would develope red rust, usually 

 around their edges, although I had in the meantime raised 

 the density by degrees to 7 per cent and 10 per cent of 

 acid. This demonstrated that the mycelia, even though 

 temporarily barren under the vaporized atmosphere, have 

 the faculty of recovering through forming new lateral 

 buds and branches and are not actually dead until 

 brown and dry. The signal success I had with a 

 Liberian tree under peculiar circumstances and taking 

 into account the periodicity of the consecutive stages 

 of the development of the fungus, have since deter 

 mined me to use, what I had before indicated as 

 a safe limit, 25 per cent, but in fortnightly applic- 

 ations only, which change in my tactics has been 

 followed by the best results. I have, in the way 

 of experiments, repeatedly employed a mixture so 

 strong, that its vapors eat the spores on fully devel- 

 oped patches as clean away, as would muriatic acid 

 a spot of rust off iron, without the least deleterious 

 effects upon yoimg leaves and flowers, which were both 

 represented on the plants under treatment. The va- 

 por produced by a dilution of 25 per cent makes very 

 short work of the spores, whilst the undeveloped spots 

 rapidly change colour, turn brown, and die. With 

 one vessel I used, common cups, I worked at a dis- 

 advantage, as carbolic acid only partly dissolves in 

 water, the thick sheet of which, overlaying the stock 

 of acid in the bottom, was obstructive to the rapid 

 and steady production of gas. The vessel I ha\'e mod- 

 elled for general use has with equal capacity nearly 

 double the evaporating surface, and a simple and in- 

 expensive contrivance in it will ensure a steady pro- 

 duction of gas, and economise matei'ial in usmg up 

 the gi'eatest possible quantity of the acid present in 

 the dilution by turning it mto vapor. Nor need 

 there be any fear of danger to the laborers handling 

 the fluid, as a properly constructed feeder will obviate 

 that and the chance of any waste. 



With Mr. Ward's experiments with carbolic vapor 

 and the conclusions he arrives at, I entirely disagree. 

 If Mr. Ward had wished to deceive himself against his 

 own Ijetter judgment he could not have improved 

 thereon. By his own showing, the most important 

 agent for the absorbence and conveyance of the vapor 

 to the foliage and the fungus patches — atmospherical 



moisture — was absent. A sporepatoh in the open air 

 under the influence of the vapor changes its appear- 

 ance several times. The older spores in the centre first 

 begin to look yellowish and attain a dry, gi-itty kind 

 of look ; the younger spores nearer the edges turn 

 brown; and after a day or two in the early mornino- with 

 the dew on the leaves or on a showery day, it will be 

 seen that the patches of spores, in good health 

 always dry and seemingly greasy and impervious 

 to wet, are as wet as the rest of the leaf-sur- 

 face, the surest sign of their death. I have seen 

 the spores on new vigorous patches die, and 

 with those following on below and the layer of 

 dead ones, fairly form a dish of brownish paste, the 

 thickness of the nib of a quill pen. The atmospherical 

 moisture impregnated with the vapor is precipitated 

 upon both sides of the leaves, thus working the des- 

 truction of mycelia and spores, and in dry time, when 

 the foliage is dry, respiration of the leaves through 

 theii' stomata continues tJie work. It will be seen 

 from the above tliat the very conditions most favour- 

 able to the growth of the fungus, calm, dewy nights 

 and close steamy days, are also tliose under which the 

 vapor is most destructive. 



So much for the action of carbolic vapour upon 

 ripe spores and upon growing mycelia within the 

 tissue of the leaves, supposed by Mr. Ward and other 

 scientists to be sajl'hj eiiscoiiced against the ordinary 

 enemies of their tribe, and this constitutes the one 

 chief point upon which I am at issue with those 

 gentlemen, much as I must admire the keenness of 

 research and observation brought to bear upon the life- 

 history of the fungus, and the valuable, because useful 

 information resulting therefrom. 



I have repeatedly seen scientists and other of your 

 correspondents lay great stress upon the action of the 

 wind in the distribution of the spores of Hemileia 

 etc., whilst it appears to me that the passage of 

 labourers among the coffee, brushing off the spores from 

 one tree and in the same manner again depositing 

 them on others, is the chief means of dissemination. 

 Here in Fiji, nearly, if not all cases of infection dur- 

 ing the time of the first introduction of the pest 

 were noticed by and reported to me as having oc- 

 curred near a landing-place or immediately around 

 men's huts, in every case plainly pointing to bodily 

 contact ; whilst infection through atmospherical means 

 in a country were coffee plantations are for the most 

 part so small and so far apart could only happen 

 through the merest chance. With you in Ceylon the 

 monthly system of weeding would sufficiently account 

 for rapid contagion. 



I was much pleased at Mr. W. Sabouadiere's letter 

 and flattered at the notice he takes of my doings and 

 writings. The Nestor of coff'ee planters recognizes the 

 soundness of the principles upon whicii I have based 

 my operations, and would go a good deal farther in 

 the application of my treatment than I ever dared 

 contemplate, even thougli I more than once hinted 

 at the expediency of removing every possible source 

 of reinfection outside of plantations under regular 

 cultivation. 



The gratuitous remarks of Mr. Schrottky upon my 

 mode of treatment I could have overlooked, had he 

 not committed the naivety of stating ' ' that he would 

 have been glad to borrow anything useful from me," 

 when he had already borrowed that which constituted 

 the chief featui-e of my process, and through which 

 he hopes to change his own, a manual and dii-ect 

 treatment, and as such a failure on the face of it, 

 into a neutral, permanent itnd successful one. Mr. 

 Schrottky 's doiiigs lack every element of original 

 conception and invention, nor will borrowed plumes 

 avaU him anything. JACOB P. STOKCK. 



