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THE TROPICAL AGRICULTURIST. 



[January i, 1883, 



2nd. Mally Middee comes next ; fruit is bitter. 



3rd. Bakka Moona. a thick strong creeper, leaves 

 thin. Tliere is also Kottang KoUy, a pepper shrub. 

 I now send you by this train a cutting of each kind 

 with fruit on und leave you to give a full description 

 of each species. When plauters purchase pepper out- 

 tings they should either purchase from some one they 

 can depend on or send a trustworthy man who knows 

 the proper kind to see the vine before the cuttings are 

 takens. Native cultivate the bad kiuds, as they take 

 the leaves for medicine and sell the fruit to traders 

 who purchase the same for mixing. — Yours truly, 



J. HOLLOWAY. 



WHAT AILS OUR COFFEE : THE FUNCTIONS 

 OF TREE FOLIAGE : THEIR LIMITS ? 



Sir, — Owing to absence from home I have not seen 

 till now the letter of "J. S." in the Observer o( the 

 10th ultimo. In reply I must inform your corre- 

 spondent that what I wrote about P. infestans, so 

 far from being "all my own" is entirely Cooke and 

 Berkeley's, authorities to whom even Mr. Stephen 

 Wilson would defer. My argument, however, is 

 quite independent of scientiflc theory, and relies solely 

 on the established facts ; Istly, that P. infestans does 

 in some way or other attack and beset the whole 

 organism of the potato plant, and destroys it root 

 and branch, and, 2udly, that H. vastatrix affects the 

 leaves only of the coBee tree, and that the tree, 

 after the severest attacks, manifests the highest vigour 

 of growth by the production of profuse flushes of 

 new foliage. Be it observed that this is the parti- 

 cular distinction between those fungi which are com- 

 paratively harmlessa,aA those which are utterly destructive. 



I may also inform your correspondent that roots, 

 properly so called, and all underground structures, 

 are quite devoid ot stomata. The fact that fuugi have 

 been found besetting the roots of coffee trees does 

 not prove that they found admission there. All 

 planters know that the sooty coat the leaves wear when 

 the so-called black bug affects them consists of a 

 fungus which lives upon the leaf without ever enter- 

 ing in, and feeds on the honey-dew ot the aphis. 



The question as to what ails our coffee trees is un- 

 doubtedly the most important that could engage the 

 attention of the coffee planter, if not of the Govern- 

 ment also, of the present time. I am far too deeply 

 impressed with the gravity of the subject, and too 

 earnest in my research to be affected by the sneers 

 and impatience of a very few who think they know 

 all about it. For my own part, I have from the be- 

 ginning of this correspondence confessed my ignorance 

 of the cause of our national raibforlune; I have soli- 

 cited the aid and co-operation of my fellow planters in 

 the search for a solution of the problem. The theories 

 which have hitherto been suggested do not appear to 

 me to fit the tacts ; on the contrary they seem, one 

 and all, to be more or lees distinctly at variance 

 with them : and it is satisfactory to me that many 

 practical, thoughtful men appreciate the in^uffici- 

 enoy of current theories, and recognize the difficulty 

 and intricacy of the question. These are not in haste 

 to offer opiniouB, but are busy in the far more useful 

 work of collecting, considering and collating the facts 

 of the case. 



The peculiarity of the ease consists in the fact that 

 though our coffee trees have suffered almost univer- 

 sally and simultaneously a ruinous diminution of their 

 fruit-bearing power, they still ret liu the capability of 

 producing profuse flushes of tine, fully-growu leaves. 



If we knew precisely what are the functions of 

 leaves, and how they are performed, we might arrive 

 at a satisfactory explanation of the anomaly. As yet, 

 however, science teaches very little and very imperfectly 

 a» to the way iu which nature works. In tho solu- 



tion of our problem we must depend mainly on careful 

 observation of the facts of our experience. These are 

 as important to the scientist as to the practical planter. 

 They are the raw material on which each must work, 

 and beyond which neither can safely go. 



What do we actually know regarding the practical 

 use of the leaves of our coffee trees ? 



Mr. Ward in his reports on Hemileia repeatedly 

 describes the injury it does to the trees as being 

 effected hy the appropriation to itself of their 

 pruper nourishment. Its mycelium, he says, tapf 

 the leaf cells, and sucks out their contents, He 

 regards this attack upon the leaf cells surround- 

 ing the spots as the sum and substance of the mis- 

 chief wrought by the fungus, and always treats 

 ot the mischief so done as of a most serious nature. 

 In certain experiments which he describes, he measures 

 the results hy the weight of leaf produced or lost 

 by the'treatment he tried. The utmost importance is 

 attached by this scientist to the loss the cotfee trees 

 sustain by the fall of leaf they suffer by an attack 

 of the fungus. In this estimate of the injury done 

 many practical planters agree. They bewail the loss 

 of foliage as of so much of the life blood ot their 

 trees, and as they view a field suffering from loss 

 of leaf they may often be heard to exclaim with 

 dismay. How can the poor trees bear crop after such 

 a loss ? Here we have the scientist and the practical 

 planter both agreeing in their evidence that a certain 

 loss of leaf inflicts serious injury and in fact causes 

 infertility in the trees so affected. 



Now let us cross-examine our witnesses and ascertain 

 the practical value of this evidence: — " Friend Pallam, 

 here you are quite cheery. The last time I was here 

 you were in the dumps about some lose of leaf 

 which was to ruin your chance of crop. Behold the 

 ground all covered with fine healthy foliage which 

 your coolies are cutting and pulling oft the same trees 

 from which the leaf-disease had only taken a mere 

 sprinkling by comparieon. If that loss of leaf was, as 

 you told me, ruin to your prospects of crop, why this 

 tearful slaughter ? " Pallam'a reply is, of course, that 

 this tremendous sacrifice of leaf is iu the usual course 

 and for the express purpose of promoting blussom and 

 crop! In tact, experience sanctions, if it does not 

 positively enjoin, the practice of pruning, involving 

 the loss of a large mass ot foliage, for the express 

 purpose of inducing crop ! One or two attacks of 

 leaf-disease cause a certain loss of leaf, whereby 

 it is held that crop prospects are ruined ; but two, 

 or (on the best cultivated estates) three, or even four 

 prunings by hand or knife, destroying a still greater 

 amount of leaf are carried out at great expense ex- 

 pressly for the sake of crop ! So much for the 

 evidence of Pallam, the planter. — Now lut us examine 

 the Scientist. Some years ago I consnlted an eminent 

 scientist about the depredations then being wrought 

 on the foliage of certain estates by a small beetle. 

 Several sample branches of cotfee were submitted to 

 his inspection to show the nature and extent of the 

 injury done, and to ascertain the probable effect, &c. 

 The learned gentleman seemed amused at ray anxiety 

 rather than concerned about the peat. His verdict 

 was that it only caused some loss of leaf which the trees 

 could easily replace. He had no fears about crop. 

 The event justified his verdict, for the same estates and 

 trees have since suffered many similar attacks, and are 

 even yet amongst the very best bearing in the island. 

 Much more recently 1 observed in certain coffee estates 

 an alarming destruction of foliage which I discovered 

 to be the work of a microscopic insect devouring the 

 incipient buds of the coming flush, whilst this was 

 itself iu an almost microscopic stage. In some places 

 more than half of the whole flush was so consumed. 

 Seveial of the affected branches were bubmitted to 

 scientists who examined them with much interest 



