THE CONTROL OF PLANT DISEASES DUE TO FUNGI. 25 
the variety ' Killarney.' Formalin may, of course, have other valuable 
uses, for instance as a fumigant or sterilizing agent. Another 
compound, hycol, proved by Miss Doidge to be virulently poisonous 
to the germ causing Mango disease in South Africa, failed in 
practice to control the malady. Miss Doidge states that hycol 
possesses about one-tenth the poisoning power of mercuric chloride 
with respect to the Mango bacterium ; formalin and cyllin approach 
it closely in poisonous effect, whilst lysol is less effective. Tetrachlor- 
ethylene may be found helpful as an ingredient of spraying mixtures, 
but this and other suggested chemicals need careful trial to discover 
their most useful application. 
Trichlorethylene may prove a valuable agent in the aseptic 
treatment of leaves apart from the cleansing effect obtained, for I 
find that weak strengths of certain commercial products which 
contain this chemical can be used on Odontoglossum leaves without 
causing the slightest injury. Spraying and washing are, of course, 
not the only operations that need activity towards improvement. 
Devices are needed in connexion with freeing soil from pathogenic 
fungi in their various forms ; cleaning seed from fungal contamination ; 
aseptic pruning against canker &c. ; prevention of the spread of 
incipient rot in Melons &c, and sterilization of the fruit-room or 
store. 
Literature Quoted. 
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PP- 38, 39- 
Butler, E. J., in Mem. Dep. Agric. India, Bot. ser. iii., Sept. 1910. 
and A. Hafiz Khan, I.e., ser. vi., Oct. 1913. 
Clinton, G. P., in U.S. Exp. Stn., Conn., Rep. 1909-10, p. 723, and III-. Built 
69, 1902. 
Cook, M. T., and G. W. Martin, in Phytopathology, iii. p. 119, 120. 
Cooke, M: C.-, " Fungoid Pests of Cultivated Plants," 1906. 
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1915- 
Hesler, L. R., in Phytopathology , iii. 5, p. 290, Oct. 1913. 
Hori, S., " A Bacterial Leaf Disease of Tropical Orchids," in Centralb.f. Bakt., 
Abt. ii. (191 1), Band xxxi. pp. 85-92. 
Horne, A. S., " Potato Diseases," Ann. Appl. Biol. i. p. 183, 1914. 
" On Tumour and Canker in Potato," in Journal R.H.S. xxxvii. p. 362, 
1912. 
" Some Troublesome Diseases of the Potato Tuber," in Rep. Brit. Assoc. 
Adv. Sci., Sheffield, 1910. 
"Symptoms of Internal Disease and Sprain in Potato," in Journ. Agr. Sci. 
iii. p. 322, 1910. 
" Blotch and Streak in Potatos," in Journal R.H.S. xxxix. (1914), p. 607. 
"Bruise in Potato," Journal R.H.S. xxxviii. (1913), p. 40. 
" On Control of Peach Leaf Curl," Journal R.H.S. xli. (1915), p. no. 
Johnson, T., in Sci. Proc. Roy. Dublin Soc. xii. (n.s.) (1909), p. 171. 
Knight, T. A., " On the Mode of Propagation of the Lycoperdon cancellatum, a 
species of Fungus which destroys the leaves and branches of the Pear Tree," 
in Trans. Hort. Soc. ii. p. 178 (read Dec. 5, 1815). 
Lewis, C. E., U.S. Exp. Stn., Maine, Rep. 1909 (pub. 1910). 
Massee, G., in Jour. Bd. Agr. xv. (1908), p. 592. 
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Trans: Acad. Scit St: Li 12, 1602; 
