COFFEA 



ARABICA 



Diseases 



THE COFFEE PLANT 



Leaf- 

 blight. 



Distribution. 



Origin. 



ruined the industry over large tracts of country. This is significantly true 

 of Ceylon, the leaf-blight having there proved so completely incurable as 

 to have caused the planters to substitute tea for coffee, as their only escape 

 from ruin. Numerous reports and monographs have been published by 

 Morris, Marshall Ward, Nietner, Bidie, Harman, Cooke, Massee, Barber, 

 etc., so that it cannot be said the subject has been neglected, but so far 

 little progress has been made of a practical nature. 



The more important diseases of the coffee plant are the following : 



1. Leaf Blight, Hemileia vastatrioc, Berk. & Broome, Gard. Chron., 

 Nov. 6, 1869, 1157; Abbay, Journ. Linn. Soc., 1878, xvii., 173-84; 

 Morris, Coffee Leaf Diseases Ceylon and S. Ind., 1879 ; Harman, Coffee- 

 Leaf Disease Bangalore, 1880 ; Jardin, Le Cafeir, 1895, 264-6 ; Tubeuf, 

 Plant Diseases, 1897, 352 ; Philip MacMahon, Queensland Agri. Journ., 

 April 1898, ii., 301 ; Massee, Textbook PL Diseases, 1899, 27, 231-2, 

 407; Lecomte, Le Cafe, 193-203; Jumelle, Les Cult. Colon., 376-7 ; Massee, 

 Rev. Genus Hemileia, in Kew Butt., 1906, 35-42. This fungal disease 

 appears to have been first observed on coffee in Ceylon, about the year 

 1869, and in South India two years later. It has since appeared in 

 Burma, China, Java, Sumatra, the Philippine Islands, and been identified 

 as met with in the coffee districts of Africa (even at Victoria Nyanza), 

 and probably wherever coffee is cultivated in the Old World. 



It has been assumed as probable that Jf. cantna a parasite found on 

 rnnthinm cnmpnHu intnni was the parent source of if. rnxtntrlje, the differ- 

 ences observable between the two fungi being in all probability the result of 

 growing on slightly different hosts. So in the same way leaf-blight, seen in 

 Natal and other African plantations, may have originated from if. WoorfH 

 a parasite found on two species of rf/ier and even on Coffen ibo. Massee 

 accordingly writes : " It is not at all necessary to assume that the coffee disease 

 has been imported along with the coffee plant from one country to another, 

 taking into consideration the wide distribution of different species of plants 

 attacked by MiftnUein, ruKtutri^ or if. tt'ootit i, both of which are capable of 

 infecting species of Coffen." In India there are some six or seven species of 

 i'n lithium, fairly abundant wild plants in the coffee area, also a species of 

 Practical Lesson. Vatigneria both in Kanara and the coffee tracts of Burma. If, therefore (as 

 pointed out by Massee), a practical lesson is to be drawn from these considera- 

 tions, to start a plantation in a district where these and other allied plants to 

 the coffee are abundant would probably mean disaster. To grow for the purpose 

 of shade, plants belonging to that family would also very possibly be dangerous. 

 All rubiaceous plants should therefore be watched for any appearance of leaf- 

 blight, and exterminated as far as possible from proximity to coffee. 



The leaves of coffee are the parts most frequently attacked by newiieia, 

 though spots are sometimes present on the young shoots as well as on the fruit. 

 These expand in size irregularly, are at first pale yellow, but hi time become 

 bright yellow and orange coloured. Though showing through on both surfaces, 

 the spores appear on the under-surface only. These are formed in dense clusters, 

 and emerge from the tissue by the breathing mouths (stomata) of the leaves. 



While touring through the coffee districts of South India I observed the grub 

 of a minute insect feeding on the spores of this fungus. I was told this had been 

 seen by the planters for some years. It would appear of importance that the 

 life history of that little creature should be worked out, since it may be the 

 planters' greatest friend. When leaf disease is at all serious it is so prevalent as 

 to render most of the methods of treatment, that have as yet been suggested, 

 quite impracticable. Syringing with fungicides, such as the Bordeaux mixture, 

 sulphuring the leaves, removing and burning the leaves, tearing off or punching 

 out the diseased portions, have each and all been advocated and tried with 

 varying, though never with complete, success. The best results as yet recorded 

 have been attained by producing a stronger, more vigorous plant, through in- 

 creasing the spacing, lessening the shade, improving the drainage, manuring 

 liberally, and restraining the pruner's knife. Under some such treatment 



384 



Treatment. 



