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TWO SCLEROTIA DISEASES OF POTATOES. 
By Professor E. J. MCWEENEY, M.D. 
The sclerotium disease of potatoes is a malady which is very wide- 
spread in certain districts, especially along the western and north- 
western seaboard of Ireland. ‘This disease assumes two distinct forms 
—one characterised by large, compact fungal masses (the sclerotia), 
hanging loosely in the pith cavity of the affected potatoe plant; the 
other by small crumpled, inconspicuous sclerotia, firmly adherent to 
the outside skin (epidermis) of the leaves and stem. On planting the 
sclerotia belonging to the first named species they gave rise to one or 
several upright stalks, each supporting a small brown disc-like structure 
called technically Sclerotinia sclerotiorum Mass. ‘his was usually 
about the size of a threepenny piece. On the upper surface of this 
were numerous oval bags called “asci,” each containing eight spores. 
If planted on a potato these spores gave rise to threads, which pene- 
trated into the plant, and produced after a while tuft-like masses of 
mycelium, the central part of which became hard and black—in other 
words, became a sclerotium. The affected plants soon die. This is 
a totally different disease to “blight,” and requires different treatment. 
The other (smaller) variety of sclerotium when planted produces, not 
a peziza, but a mouse-gray mouldy growth called “ Botrytis.” “This 
mould seems to be capable of attacking living potato plants. After 
killing them it produces its minute sclerotia on their withering stems 
and leaves. It never develops into a peziza, nor does the other peziza 
producing sclerotium ever produce a botrytis. By these studies, 
mostly carried on in the laboratory at the Albert Model Farm, 
the existence of two separate diseases of the potato, both characterised 
by sclerotia, and both eminently preventible has been demonstrated. 
The proper course to take is to carefully destroy by fire the withered 
remains of the potato crop each autumn, and not to grow potatoes on 
the same plot for several consecutive seasons. Deep cultivation also, 
with a view of burying the sclerotia out of harm’s way, is very 
advisable. ‘Though neither of these diseases is so much to be dreaded 
as the “blight,” yet in certain districts they doa great deal of damage 
to the crop. . 
