MILDEW, specifically, any fungus belong ing to the group Erysiphacee, the powdery or true mildews, and Peronosporacece, the downy or false mildews; loosely, many plant diseases, especially the rusts and smuts of cereals, and some not of fungous origin; vaguely, molds of any kind upon preserved fruit, clothing, walls or other materials, the origin of which is more or less organic. The powdery mildews develop mostly upon the outside of the host plants, which they enter only by means of their suck ing organs of attachment (haustoria). In warm weather they develop innumerable spores upon erect branches and later produce thick-walled resting spores which germinate in the spring. Upon the host plants they usually appear as a sort of bloom, but later they often cause dis tortion of the leaves and not infrequently the death of the host. Being mainly upon the sur face they may be combated with any fungicide ;q.v.), and often with sulphur, either in the form of powder or vapor (not burned) evap orated without flame. This method is widely practised in greenhouses. Some of the best known are rose mildew (Sphcerotheca pan nosa), gooseberry mildew (S. mors-uve), hop mildew (S. castagnei), cherry, pear and apple mildew (Podosphera oxycanthe), wheat mil dew (Erysipha' graminis) and grape mildew (Unicinula spiralic).
The downy mildews all live within the tis sues of the host plant, appearing outside the surface only when producing summer spores (conidia) which usually give a downy appear ance to the infected spots. The resting spores are produced internally and make their escape in the following season when the tissues of the host (leaf or other part infected) have de cayed. They cannot be combated like the pre ceding, because of their habit of feeding in ternally. Fungicides (q.v.) may be applied prevent attacks, however, and this, together with the destruction of leaves in autumn and general cleanness of the premises, are believed to be the only safeguards. Among the best known and most destructive are Potato rot, blight, or mildew (Phytophthora infestans), lettuce mil dew (Bremia lactuca'), damping-off fungus (Pythium debaryanum), downy mildew of the grape (Plasmopara victicola), radish mildew, also found on other members of the Crucifers (Cystopus candidus), melon and cucumber mil dew (Plasmopara cubensis) and onion mildew (Peronospora schleideniana).
The rusts and smuts which are sometimes called mildews are discussed elsewhere. The mildews, so-called, which appear upon leather, wall-paper, cloth, etc., belong to various other groups. Since they are generally seen only where dampness prevails, especially in cellars and closed rooms or houses, they may be pre vented more or less effectually by the adequate ventilation of such places. And having gained a foothold in these places they may be destroyed by liberal applications of whitewash, in which copper sulphate or sulphur have been mixed, or where this cannot be applied, by burning sul phur in the closed quarters. This last remedy may also be used where cloth is attacked. Awn ings, sails, etc., should be thoroughly dry before being stored or folded for any considerable time. They may also be soaked in a solution of copper sulphate and then dried. Until this is washed out by rain it will act both as a pre ventive of attack and will often save fabrics if not too far gone.
MILE (Latin mille, a thousand, a Roman mile being 1,000 paces), a measure of length or distance. The English statute mile, fixed in the reign of Queen Elizabeth, is 1,760 yards. The geographical mile, which is commonly used by the navigators of all nations, is one-sixtieth part of a degree at the equator. In many countries the kilometer now holds the same the English statute mile in Britain. The following are some of the principal stand ards of miles or leagues which are or have been in use in the principal countries of Eu rope: The English statute mile is generally used in the United States.