“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.

“5.  After a heavy digging where roots have been cut.

“6.  After pruning without manure having been applied, or from want of digging.[57]

“7.  Even after manuring when the trees have large succulent roots in an immature condition—­generally a sign that fibrous surface roots are deficient, and that large, deep-feeding roots are present in excess.

“8.  After large quantities of green or rotting weeds have been deeply buried, or large quantities of acid, unrotted, or forcing manures have been applied.

“Leaf disease is also liable to occur: 

“1.  In poor gravelly soils, and on land which has caked in the hot weather, or become unmanageable during rain.

“2.  On land where ill-balanced manurial preparations have been used.

“3.  In soils suffering from a deficiency of the available supply of phosphates and alkalies.

“4.  Under unsuitable shade trees.”

Now it is to be observed that these are preventable causes, or aggravations of leaf disease, and, if carefully attended to, the planter will have little to apprehend from leaf disease.  Mr. Anderson, in his communication to me, lays, and very rightly, particular stress on the maintenance of the physical condition of the land and its state of fertility.  And it is satisfactory to find that he is exactly confirmed by Mr. H. Marshall Ward in his third report (dated 1881) on coffee leaf disease in Ceylon, and he points out (p. 3) that “Leaf disease appears to affect different estates in different degrees on account of varieties in soil, climate, and other physical peculiarities.”

“But,” he continues, “I would draw particular attention to this.  Careful cultivation and natural advantages of soil, climate, etc., enable certain estates to stand forth prominently, as though leaf disease did not affect them, or only to a slight extent, while poor nutrition, the ravages of insects, etc., have in other cases their effects as well as leaf disease.”  Or, in other words, he states that, as was suggested to me by Mr. Reilly—­a planter of long experience near Coonoor on the Nilgiris—­that much loss of leaves, which has been attributed to leaf disease, is often due to other causes.

Mr. Brooke Mockett—­one of the planters previously alluded to—­informs me that “Leaf disease is certainly worst (1) on trees that are cropping heavily, (2) on trees that have been severely pruned (heavy pruning being ruination in my opinion), (3) on plants under bad caste shade trees (these plants it seems to cripple), and (4) on plants in the open.”