New Form of Potato Disease.

Otago Witness, Issue 1942, 7 February 1889, Page 8

New Form of Potato Disease.

We noted last week that some potato shaws had been sent to us by Mr Gordon, Balmuchy, Ross-shire, which evidently snowed a new form of potato disease. At our request Mr Gordon forwarded similar specimens to Mr Worthington G. Smith, F.L.S., London, the eminent author of "Diseases of Field and Garden Crops." Mr Smith found on examination that the disease in question was caused by a fuugus named Reziza Postuma. This disease was first noticed in the month of August 1880 by Mr Ambrose Balfe, secretary of the Royal Horticultural Society of Ireland. The potatoes among which it appeared were champions, planted in land which bad been reclaimed from bog eight years previous to the outbreak of the disease. Many efforts were at that time made by Mr Smith and numerous friends to make the sclerotia or compacted masses of fungus spawn germinate, but their efforts proved resultless. Numerous inquiries were made of potato growers, but this sclerotia appeared to be lost to the country, and nothing more was heard of them till a paragraph appeared in Nature of July 19, 1883, in which was described a so called hitherto unknown form of potato disease, which had been making steady progress near Stavanger during the previous 10 or 12 years. This disease at Stavanger was clearly identified with the one discovered in Ireland in 1880, and a few weeks later Mr Stephen Wilson, of North Einmundy, discovered it among potatoes grown near Aberdeen. In the same year it spread to some extent over various districts in Ireland, but it has not sincß been heard of. The fungus spawn of the latter year germinated satisfactorily, and was proved to be quite a new species of fungus, to which the name of Pema Postuma was theu applied. The reproductive power of this fungus is extraordinary. The sclerotia, if left iv the ground, will germinate by the following July, and produce slender stems with expanded tops, charged with millions of sporidia, which sail away through the air. A vast number of the sporidia must perish, but such as fall upon the potato plants germinate at once, cover the stems with spawn, and speedily reduce the haulm to a putrescent mas 3. Mr W. G. Smith recommends that the stems of diseased plants should be burned, as that is the only way by which the spawn of the fungus can be destroyed.. If, on examination of the bad stems, it is found that many of the sckrotia have dropped from them, the top surface of the ground should, if possible, be raked and burned. For further information on this subjeofc, readers are referred to Mr Smith's handbook on* the "Diseases of Field and Garden Crops."—North British Agriculturist.