Leaf disease is the common name given to the attack of Hemeleia 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 Hemeleia Vastatrix.