The year is conjectured from the reference to an 1879 seedling.

Since 1876, Torbitt had been corresponding with CD about his attempts to breed a blight-resistant potato, and occasionally sending specimens (see Correspondence vols. 24–6). He previously sent seedlings (including an ‘1875 seedling’) shortly before his letter of 26 June 1878 (Correspondence vol. 26).

The year 1879 was exceptionally cold and wet (Gardeners’ Chronicle, 27 December 1879, p. 820). In his letter of 4 November 1879, Torbitt wrote that his statement that all foliage of the current year’s seedlings had been destroyed by the parasite was a mistake. The parasite responsible for potato late blight is Peronospora infestans (a synonym of Phytophthora infestans), a species of oomycete or water mould parasitic on the potato.