Though coffee in Mysore is liable to two diseases, and to the attack of one insect, these, when the cultivation is good, and the shade suitable in kind and degree, are not likely to cause any uneasiness in the minds of the planters. But it is, of course, necessary to go carefully into the whole subject of these diseases and the insect attack, in order to bring out fully the steps that should be taken so to cultivate and shade the coffee as to render these evils as innocuous as possible, and I have therefore, in addition to my own knowledge, taken pains specially to procure from two planters of long practical experience their views. The views, I may say, of Mr. Graham Anderson as regards leaf disease are particularly valuable, as he has paid much attention to the subject.
Leaf disease is the common name given to the attack of Hemeleïa Vastatrix, a fungoid plant which distributes its spores in the form of a yellow powder. These alight on the leaves of coffee, and in weather favourable to the fungus, will germinate in about a day, and the fungoid plant then roots itself between the walls of the leaves. After the plant has completed its growth, which it generally does in about three weeks, more spores are produced to fly away with the wind, or be scattered by the movements of the coolies amongst the coffee, and thus the disease spreads. A great deal, of course, has been written about it, and those who desire more particular information may refer to Mr. Marshall Ward's report on coffee loaf disease in Ceylon. It is sufficient to say here that when the attack is severe the tree is deprived of its leaves, or of a large number of them; that much injury to the crop results; and that both the tree and the soil are heavily taxed in replacing the foliage that has been destroyed.
Leaf disease has probably existed[[56]] in Mysore as long as coffee has, but was, from the small amount of it, so entirely unnoticed, that, when I wrote my chapter on coffee in the "Experiences of a Planter," more than twenty-two years ago, I had never heard of it, nor, I am sure, had any of my neighbours. A trick, however, I once played on Mr. Graham Anderson's cousin about thirty years ago, enables me to trace it backwards so far with certainty. On coming through his plantation on one occasion, I picked oft a very large yellow coffee leaf, and placed it below the first of several plates with the aid of which he was helping his visitors. When the servant lifted the first plate, there was the leaf, and I said to my friend, "There are your golden prospects." Many years afterwards Mr. Graham Anderson recalled the incident to my memory, and said, "That was the leaf disease." But it was not till leaf disease appeared in Ceylon in a severe form that our attention was called to the subject, and since then leaf disease has undoubtedly increased, and, in the opinion of one of the two experienced planters I have consulted, has caused much loss directly and indirectly, while the other informs me it has caused much loss on some estates. But I confess my own observation causes great doubts in my own mind as to whether the losses of leaves which planters attribute to leaf disease are entirely owing to that cause, and I was much struck with what Mr. Reilly, of Hillgrove Estate, Coonoor, said to me on the subject; and when we were discussing leaf disease in general, he observed that it was often said to be the cause of leaves falling off, when their doing so was really owing to an over heavy crop of coffee. Then with our dry east winds many leaves become yellow and fall off, and some become so because they have been injured by the pickers, others from rot, and others from old age, and all these leaf losses are commonly put down to leaf disease, so that, taking all these points into consideration, I find myself quite unable to determine, even approximately, the amount of loss arising from Hemeleïa Vastatrix.
But of one thing, however, I do feel absolutely certain, and that is, that when the land is well cultivated, manured, and judiciously shaded with good caste trees, leaf disease may be reduced to such a degree that we need not trouble ourselves about it, and I feel equally sure that the most important of all the agents for controlling and limiting the disease is the shade of good caste trees. And as to the effect of shade upon Hemeleïa Vastatrix, I made particular inquiries when visiting estates in 1891 on the slopes of the Nilgiris, and conversing with planters on the subject. One manager went so far as to say that there was no leaf disease under the shade trees. Mr. Reilly, of Hillgrove Estate, said there was much less leaf disease under the shade trees. Another planter of great experience told me that leaf disease begins on the coffee in the open, and then spreads into even the finest trees under shade, but that those are affected in less degree. "In the end," he said, "You see the estate all yellow, but with green patches of coffee under the shade trees." In short, I found that all the planters I consulted were agreed in saying that there was but a small amount of leaf disease under the shade trees. The estates on the Nilgiri slopes have been originally all in the open, but latterly shade has been encouraged on some estates, but not to a degree which in Mysore would be called shade. However, the shade was quite sufficient, as we have seen, to illustrate the important fact that shade can control leaf disease. And as shade can control leaf disease, I need hardly say that it is of the utmost importance (just as it is as regards Borer), to carefully fill up at once all spots where shade is deficient, because this deficiency encourages leaf disease, and forms a breeding ground for spores to fly into the surrounding coffee. Open spots here and there may not strike one at first sight as being of much importance, but if they are all added together, the planter will see that they will amount to a considerable area of land, and quite sufficient, at any rate, to inoculate his plantation with leaf disease.
The reader will observe that I have said that leaf disease may be reduced within practically speaking harmless limits if the coffee is judiciously shaded with good caste shade trees, and I would call particular attention to the term good caste trees, because bad caste shade trees will not control leaf disease. On the contrary, Mr. Graham Anderson informs me that he has seen worse leaf disease under a dense covering of bad shade trees than he has in the open, and he also informs me that, though shade is the backbone of our success in Mysore, he has had more misfortune from all causes when his estate was under the heavy shade of bad caste trees than he has ever had since, though many places are not yet properly covered with the good kind of shade trees which he had planted to take the place of the bad ones he had removed. I am much indebted to Mr. Graham Anderson for information on the subject of leaf disease, and he has been kind enough to enumerate the following conditions under which leaf disease is liable to occur in the cases of good soils under good shade:
"In the case of good soils under good shade trees," writes Mr. Graham Anderson, "leaf disease is liable to occur under the following circumstances, or at the following times:
"1. From the soil being saturated at some critical period of growth, particularly just when secondary growth commences in September.
"2. During the time when the plants are maturing a heavy crop.
"3. After the plants have been exhausted by ripening a heavy crop.
"4. After heavy weeds—particularly if late in the season.