The Potato Blight.
Unquestionably the most important items of commercial news that we have received from the Old World for some time past are those relating to the ravages of the potato disease m Ireland, and some parts of England and Scoiland. So far no hint lias been given of its nature, whether it is an increase of virulence m one of the common diseases—dry rot or wefc rot, both due to fungus growths— or a reappearance of the destructive disease which caused the terrible famines m Ireland and other countries m 1846 and 1847. It appears that no satisfactory explanation was found for the devastating disease of the 40's. Many observers ascribed it to insects, acari, and infusoria, but these were not always present, and therefore were more likely a consequence of the disease and not its cause. It is otherwise, says an article m "Chambers' Encyclopedia," with the mould or mildew fungus Botrytis ivfestwis, which is always present, although probably, like other parasites, it generally attacks an already weakened plant. Mr Berkeley, a botanist of the first rank, states :—" The decay of the leaves and hau}m m the potato murrain is certainly due to Botrytia infeskins, and its appearance m the diseased tissues of the tubers, when exposed to the air, makes it at least probable that it has a close connection with that destructive murrain which m many instances does not appear alone, but accompanied by other diseases. The mould may be traced spreading round the edges of the brown spots on the leaves, and soon destroying the tissues on which it was developed." This destruction results not only from the fungus feeding upon the juicesof the plant, bufc from its obstructing the elaboration of sap anc a}l the processes which m a healthy state take place at the nurface of the leaf, This mildew generally appears first m the leaves, and thence extends to the tubers, but it h?ts. appeared m the tubers of early kinds of which the leaves had died away before the season when the disease breaks out. It is on the under side of the loaf that the Botrytis is found ; its mycelium or roots abound also m the i diseased tubers, which when cut produce an abundant crop of mould from the fresh surface ; and it sometimes vegetates also from the natural surface. The same fungus has been found m the berries of the tomato when diseased, and on the leaves of other plants of the potato family, but never on any other ortler of plants. It }tj said thac the starch cells m the tubers are riot affected by the potato disease, so thai as good potato starch can be made from unsound as from sound tubers. In 3.846, )jowever, but little advantage was taken of tin's faqt, partly from ignorance of it, partly from : 'fear, that the starch might' prove unwholesome; and partly from Want of' machinery to grade the diseased potatoes before they became rotten. A pWiisposiny cause to widespread diseases among cultivated 'planks', it is asserted, is excessive cultivation. Plants. ertensiy,ely cultivated m any district, however successfully they may be cultivated for a time, are sure to fail at last. Then a pwojvle who depend exclusively, or almost exclusiyejy, for their subsistence upon one such p^lanty doom themselves to terrible privations when that failure does occur,!?
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The Potato Blight., Ashburton Guardian, Volume VII, Issue 2510, 5 September 1890
The Potato Blight. Ashburton Guardian, Volume VII, Issue 2510, 5 September 1890
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