I04 



THE TROPICAL AGRICULTURIST. 



[August i, 1882. 



ficially treated and pruned for a generation, but 

 in a remote, young district, where the plantations 

 were still in their infancy, and where, since then, 

 they have yielded heavy crops for years without 

 being so much troubled as other and older districts 

 which were visited later on by the dire enemy. 

 Curiously enough, only during the last few weeks, 

 the theory has been revived in Ccylou that in prun- 

 ing — the free use of the knife — the coffee planter 

 has one of the best means of fighting l^af-disease, 

 and we believe the opinion is very general that for 

 s>ome seasons there has not been enough of pruning 

 and handling owing to different causes, chiefly want 

 of money, on most of our coffee plantations. J3ut 

 apart from this we have the case of a Dimbula pro- 

 prietor who, in the face of warnings from his neigh- 

 bours and old planters generally, has systematically 

 gone in for severe pruning (accompanied by liberal 

 cultivation) for five years back, and whose property, 

 in place of being ruined ns was prophesied, has 

 steadily given crops much above the average, promis- 

 ing well even in this year of almost universal short 

 crops. So again we have liad one of the oldest planters 

 in Uva declaring that he has no fear of leaf-disense 

 if he is allowed the free use of the knife, and there 

 are not a few now who are coming round to a belief 

 in heavier pruning as one means of getting crops 

 from plantations still afflicted with the leaf fungus. 

 Of course, we may be told that the treatment re- 

 ferred to must inevitably wear out the tree sooner or 

 later ; but five years of steady cropping is a long 

 period in the middle life of a coffee plantation in these 

 days, and when the trees still continue to look as fresh 

 and vigorous as any in the district, it is hard to 

 gainsay the teachings of experience even when opposed 

 by so logical a theory as that propounded in tlie fol- 

 lowing article : — 



A discussion is at present going on at home between 

 Mr. E. M. Holmes, f. l. s., and Dr. W. T. Thiselton 

 Dyer, on the "Causes of Coffee Leaf-disease. " So far 

 as we can make out from a perusal of the correspond- 

 ence passing between these two eminent gentlemen, 

 they are both arguing beside the (luestion. It is ad- 

 mitted on all hcindsthat weakly or badly nourished plants 

 are more liable to be attacked than are healthy bushes. 

 This, however, affords no evidence as to the ciiuse of 

 the disease, although it seems to confirm the opiuinn 

 we have always held, that there is no such thing as 

 leaf-disease at all. If it were a leaf-disease onl.v, all 

 bushes would be similarlj' liable to attack ; but if it is, 

 as we believe, a root-disease, then the comparative im- 

 munity from attack enjoyed by the heiilthy plant is 

 intelligible. Mr. Holmes, while not adtiiitting this, 

 unconsciously brings forward evidence in support of it, 

 ■when he s.ays that the disease would be much less 

 deadly if all the coffee plants in Ceylon had been 

 newly obtained from a wild source. No doubt, because 

 the causes which we affirm have tended to bring on 

 the disease, would never have affected the " plants 

 newly obtained from a wild source." Mr. Holmes 

 seems to think that the comparative immunity enjcyed 

 by the Liberiau coffee, is "because the texture of the 

 leaves is unfavourable to the development of the fungus." 

 There may be some ground for this, but we suspect 

 that the leaves of this variety will be equally affected 

 with the others, after a few years of the same treat- 

 ment. Dr. Dyer reccmmeuds a renewal of the plants 

 on an estate from seed collected after the fasliion of 

 pedigree graiu, This isecjuivaleut to telling planters to 



bear with the ills they have, and sacrifice their fortunes 

 for the benefit of their successors. Pedigree wheat can 

 be well selected after ten years, but as the coffee plant 

 does not bear seed during its first year, thirty years 

 would elapse before a carefully selected supply of seed 

 could be obtained, and after all the result would 

 only be problematical. This proposal of Dr. Dj'er's 

 also admits the correctness of our theory that the 

 disease is a ladical one ; else why try to get rid of 

 it by such a thorough-going renewal process? 



Regarding the comparative immunity enjoyed by Liber- 

 iau coffee, Mr. Holmes says :— " I attribute the fact that 

 Liberiau coffee is less subject to the disease, to the plant 

 having had as yet hardly time to have its vitality 

 lowered by excessive bearing, or by growth in soil de- 

 ficient in metallic nutrition for the plant." This shows 

 a true understunding of his subject. In this sentence, 

 Mr. Holmes hits the two principal causes of disease — 

 " excessive bearing" and "deficient nutrition." In tea, 

 there are two other causes operating to deteriorate the 

 plant, and these are the cultivation for leaf as opposed to 

 seed, and the excessive pruning to which the bushes 

 are subjected. This difference allowed for, the causes 

 of lenf-disease — so called— in both coffee and tea. plants 

 are the same. 



We shall now direct attention to these causes some- 

 what in detail. Nature, in its production of fruits 

 and seeds, works under fixed rules, and these rules we 

 deliberately set aside. In the cultivation of coffee, 

 the financial exigencies of the industry malie it imperat- 

 ive that we should, if possible, obtain a heavier crop 

 than would be produced under the ordinary operations 

 of nature. To efffct this, we resort to pruning, which 

 has the effect of a stimulant on the plant, constraining 

 the plant to throw ont fresh fiowers and seed-bearing 

 shoots. There would not, perhaps, be ao much harm in 

 this, if we helped the tree by a little nourishing treatment, 

 but herein we fail. When a man has extra work to do, he 

 must be well rested and better fed than usual : other- 

 wise his power to perform that extra work is weakened. 

 This does not seem to have been taken into account 

 in coffee cultivation. Year after year we strive for 

 an extra crop, without exerting ourselves much in the 

 way of feeding the hardworked plant. This then is 

 the first cause of disease. Ne.xt comes what Mr. 

 Holmes calls, "soil deficient in metallic nuti'ition for 

 the plant." In other words, the artificial forcing of 

 tlie plant results in depriving the soil of what is 

 commonly known as plant-food. Now, in the cultiv- 

 ation of ordinary crops, the farmer knows ihat, if he 

 wants a good crop, he must manure his land, and if, 

 from whaiever cause, he is not in a position to apply 

 manure, he, as a matter =)f course, looks for a poor 

 crop. This sort of commonseuse does not enter into 

 tea or coffee planting ; good crops are expected year 

 after year, and thorough mauuring— in fact, manur- 

 ing at all— is the exception rather than the rule. 

 Judicious pruning may enable this end to be 

 achieved for a time, but a period arrives when nat- 

 ure will not stand this sort of treatment longer; 

 and such results as this disease immediately show 

 themselves. 



Now, let us look at the treatment to which the tea 

 plant is subjected. The pruning process seen in the 

 coffee plant is very much aggravated in tea cultiv- 

 aion. During the winter, wlieu the plant is resting, 

 pruning takes place, and it is a much more thorough 

 process thau it is in the case of the coffee. There 

 is also this to be said, that each time the bush is 

 plucked, it undergoes a serious pruning, and that 

 too of tlie most valuable leaves and shoots the struggl- 

 ing plant po-sesses— viz. the very youngest and 

 the most active in the economy of plant- life. In 

 December, we will say, the plants get their annual 

 heavy pruning, and shortly thereafter growth begins. 

 The very act of pruning compels the plant to make 



