From J. D. Hooker   12 March 1878

Royal Gardens Kew

March 12/78

My dear Darwin

I have gone over your draft very carefully & written to Farrer expressing my opinion that Mr Torbits plan should have a trial, & is a fit subject for Govt. aid.1 I have slightly modified what I said about the Liberia Coffee, since it has lately been found to be attacked by the Hemileia a parasitic Fungus like the Pernospora of Potato as badly as ordinary Coffees, but it has resisted the fly.2 The reason is this, that the hard cuticle is an obstacle to the “fly” which has to gnaw through it before it commences its ravages, whereas the Hemileia, like the Peronospora enters by the stomata, & the stomata of one Coffee are like those of another.

Ever affec yrs | Jos D Hooker

1
CD’s letter to Hooker has not been found; it was a corrected version of his letter to Thomas Henry Farrer, expressing support for James Torbitt’s experiments on the breeding of blight-resistant potatoes (see letter to T. H. Farrer, 7 March 1878 and enclosure).
2
See letter from J. D. Hooker, 2 March 1878 and n. 3. Hemileia vastatrix is a fungus that causes coffee-leaf rust; on the severity of the disease in Ceylon (Sri Lanka) and south-east Asia, see Gardeners Chronicle, 6 November 1869, p. 1157. CD reported that, according to Hooker, Liberian coffee withstood ‘White Fly’ (enclosure to letter to T. H. Farrer, 7 March 1878). Aleurothrixus floccosus (woolly whitefly) attacks the leaves of coffee. Peronospora infestans (a synonym of Phytophthora infestans) is a type of oomycete or water mould parasitic on the potato, but at this time it was classified as a fungus (see Bary 1876).

Please cite as “DCP-LETT-11417,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-11417