Abstract
LONDON. Association of Economic Biologists, November 18.—Sir David Prain, president, in the chair.—E. J. Butler: Meteorological conditions and disease. The meteorological conditions known to influence diseases of plants are chiefly temperature, humidity, and radiation. The influences are most marked in Continental climates, as the amplitude and duration of the variations are greater than in countries like England. They act both on the host-plant and the parasite, but to judge of their full effect it is often necessary to test them on the host-parasite complex, since the influence on either host or parasite alone may not give a true picture of what occurs in the interaction of the two which constitutes disease. Small variations, amounting to not more than 5 per cent. in relative humidity or 10° C. in temperature, if prolonged, may be sufficient to determine whether a parasite will cause nearly 100 per cent, infection or none at all. In India the author has found that several diseases are so sharply restricted in their distribution by these factors that it is possible to demarcate the areas in which they cannot occur, and also those in which they occur only in special conditions arising in exceptional years, from those in which they normally occur every year. The same is true in the United States. Exact evaluation of the factors concerned is possible by rigidly controlled experimental methods, but not by field observation alone.
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Societies and Academies. Nature 108, 515–518 (1921). https://doi.org/10.1038/108515b0
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DOI: https://doi.org/10.1038/108515b0