34 



THE TROPICAL AGRICULTURIST. 



[July 2, 1883. 



lurking leaaing towards fatalism ia some remote coraer 

 of uiy owa psycliioal make-up, but not in the abject seuse 

 of tlie proverbial Turk. 



If there is anything I blame myself for, it is for 

 speak lug perhaps too early of my discovery, but I was 

 satisfie I from tlie results I hud that 1 was on the 

 right track, and, when I did speak, I distinctly warned 

 planters not to rush into experiments until they had heard 

 more from me ( Gardeners' Chronicle, February 8th, 1S82) 

 beo.tuse I then saw room for improvement. The very parl- 

 ous, and often very great teiiacity of life of the spores of 

 Hemileia vaslalrijc oompolled me to gradually change 

 my system from the employment of restricted to that of 

 auiited evaporation of the acid, all else remaining the 

 same. The tl lating wicks of rolls of bagging once 

 recommended 1 have now altered into upright collars 

 of the same material, and anyone may adopt these 

 without any alteration in his arrangements. Pre- 

 suming that the vessels are of the required diameter 

 and charged with good acid, take fairly round bagging, 

 cut it into strips of about 2J inches in width, of 

 eufficietit length (about 1 foot) to go once round the 

 inner oircumfereuoe of the vessel, put it down edge- 

 ways to the bottom of the vessel, have it stand strnight 

 up if possible against its side, but take care that, 

 it the vessels are shallow, it must not band outwards 

 and overhang the rim, as it then would act as a 

 syphon and cause loss and possibly damage. In a few 

 minutes the collar to its very top edge will be moist 

 with acid and give off volumes of vapor which no fun- 

 gus can resist. Old acid, which had been lying for 

 months in the vessels and which I had thougUt eflFate, 

 began to act again and continued for several weeks 

 afterwards. I do not think it necessary as yet 

 to depart from my original estimate of 30 vessels 

 per acre and their cost with four three-monthly sup- 

 plies. This latest improvement of mine so mucli in- 

 creases the evaporating surface and accelerates the 

 evolution of the vapor, that I would not recommend 

 any closer arrangement of the vessels, until the density 

 of the gai was still insufficient to kill all the spores 

 under all conditious. Besides, without some artificial 

 way of promoting evaporation, the acid would lie 

 comparatively idle in the vessels, nor would accord- 

 ing to my experience the three-monthly charge 

 evaporate in that time. 



From what I can gather, the eflects of the disease 

 and the fungus itself are far more pronounced with 

 you and obstinate thau with our comparatively 

 recently infected trees, insomuch as, according 

 to the statement of one of your correspondents, even 

 after a decided abatement of the fungus on a field 

 under treatment, a fall of leaves took place, showing 

 very few traces of fungus ; whilst with me the first 

 effect of the treaiment wat that the whole foliage, 

 even though copiously marked with wornout spore- 

 patches and dead pin'pots, remained on tlie trees. 

 This diiierenoe in behaviour under identical conditions 

 can only be charged to a state of greater exhaustion. 

 Under continued treatment you will find that, 

 as the fungus becomes thinner and weaker (1 aay 

 30 advisedly, because it does sicken by degrees), your 

 trees will, although perhaps still bearmg the marka 

 of the fungus, retain their foliage and resume their 

 crop-bearing. What it took ten years or more to 

 effect is not to be reooverad by magic. 



A good deal has been saii about more or less dis- 

 ease-proof trees among Libenan and Arabian 

 coffee, and from my observation I have come to the 

 conolusiou that the readiness or otherwise of certain 

 types, varieties and individuals of either species to 

 receive infection much depends at first upon the 

 textttre of the foliage, until even such plants become, 

 by repeated attacks, however slight, by degrees de- 

 biliiateil, lose their individual peculiarity of texture 

 epidermis, and beeome at last .\8 subject or nearly so 



to the inroads of disease as their neighbours. Mr. 

 Ward, with whom I entirely a.sroe in everything, 

 except the wellknown point, speaks of an experiment 

 he made of sowing spores upon the top of leaves, 

 only succeeded after removing the epidermis, 

 under all other conditions, through its denser 

 texture and greater thickness than that of the 

 lower side of the leaf, impervious to the germ tubes 

 of the spores. It takes no great stretch of fancy to 

 expect that the longer a tree suffers and the oftener 

 it has had to make a new flush of foliage, which 

 foliage, formed out of season, would of necessity be of 

 less substance and lighter texture than others formed 

 under normal conditions, the more readily the germs 

 will enter. It may be for this reason that more spores 

 (germs) survive as yet than ought to be expected, 

 because they enter before the enemy has had time to 

 destroy them, although, according to my experience, 

 they are not even then beyond reach. I think a 

 destruction of 90 % for the first season a very favorable 

 result under the conditions given, with badly diseased 

 fields all round the area under treatment and the 

 atmosphere charged with myriarls of floating spores. 

 Reduce the remaining balance at the :: \,me rate and 

 what will be left? A practically clean field ! Let the 

 treatment become general and abandoned plantations 

 destroyed, the clouds of floating spores rarefied, and 

 marie the difference in the results. But I still un- 

 compromisingly maintain that, if my system is carried 

 out strictly, as what / conceive it to b . and as what 

 I have been at great pains to describe it to you and 

 others, tiot a spore can survive. Intelligent management 

 of your estates will do the rest, and you will find 

 your trees recover faster than they declined. All the 

 physical powers of resistance shown by them in their 

 long struggle will be doubly in their favour on the 

 way to recovery, when once they reach the turning-point, 



I have not by any means given up my intention of a 

 personal visit to you, which I hope soon now to be able 

 to carry out. — I remain, dear sir, yours very faithfully, 

 , JACOB P. STORCK. 



P. S. — On referring to the paper containing Sir 

 W. Hooker's professional report upon the expedi- 

 ency of offering a reward for a de facto cure of Hemileia 

 vas'atrb:, it strikes me very forcibly that he meant firstly 

 to punish a certain want of conciseness in the use 

 of terms on the part of the petitioners, and that 

 secondly, he did not show sufficient appreciation of 

 the different conditions under which the prospect of 

 an award has proved "worse than useless" for a cure 

 against phylloxera in France, and what we find to 

 be' the case with Hemileia and the few men who 

 have with more or less claim to practical success 

 emleavoured to find a reiutdy for it. If I am rightly 

 informed the Government of Java haj offered 

 and subsequently withdrawn an award for the sup- 

 pression of leaf -disease (or its cause) which was open 

 tor eompetion for some time without a single claimant 

 appearing. In the English colonies no award had ever 

 beeu officially offered : but, although au.fone lucky 

 enough to solve the question would with good 

 reason eventually expect some acknowledgment for 

 his services, and there have, with tbe exception of 

 One or two rather wild schemes which were plucked 

 at once by the public press, beeu only four com- 

 petitors for the honor in the Held — Messrs. Morris, 

 Schrottky, Ward and tha writer, all of whom have 

 b'en equally honest and earnest in their several pro- 

 p^isils — a very different aspect of things to the dis- 

 graceful scramble said to have taken place in France, 

 if you consider that those men camj forward wiih- 

 out any definite prospect of award in tbe event of 

 euccess. 



In the event of an award being offered I would 

 suggest, by waj' of safeguard ngainst abuse, that 

 eacii competitor for it should submit, as first con- 



