FUNGI, ECONOMIC. Species of fungi that may directly or indirectly affect man's welfare. Of those that affect man directly, the edible and poisonous species and some parasites, such as barber's itch, etc., may be mentioned as examples (see FITNor, EDIBLE AND POISONOUS ; MUSHROOM ; TRUFFLE) ; of those that affect him indirectly are plant diseases, molds, sonic ani mal diseases, etc., whose functional activity may result in monetary or some other kind of loss. A large majority of fungi (saprophytes) are capable of living only on decaying organic matter, and since they do not ordinarily attack living plants, they do not produce plant diseases. They are therefore of little economic importance except as they occur on fruits and other food stuffs, timber, clothing, etc., when they may be considered harmful. On the other hand, many of these organisms are more or less beneficial, since they act as scavengers in the destruction of organic matter which would long cumber the earth if dependent upon the slow process of chemical oxidation. Under abnormal conditions of moisture, temperature, etc., some saprophytic fungi (usually called facultative parasites) are able to attack and injure living plants. The parasitic species (another large group) occur normally upon living plants and animals, from which they derive their sustenance. The plant or animal upon which they live is called the host. The relationship between host and parasite is more or less intimate, and as the economic plants are affected, the importance of the para site is the greater. In some cases the fungi are of positive benefit to man because they (entomo genous fungi) destroy noxious insects, as locusts, grasshoppers, flies, scale-insects. etc.: others live at the expense of fungi that are themselves injurious to plants of value to man, as in the case of Barium filum. a parasite of the injurious asparagus rust. The number of fungi that at tack living animals is large, and in sonic cases the attack is very destructive. Young fish in hatcheries are subject to diseases due to fungi; and higher animals often suffer similar attacks. A lung disease of horses is caused by the presence of the fungus Botriomyees, and the various forms of ringworms, favus, barber's itch, etc., are all due to fungi.
When mention is made of fungous diseases the term commonly refers to diseases of plants caused by attacks of parasitic fungi. The num ber of species of such parasitic fungi is very large, and nearly every garden, orchard, and greenhouse crop may be attacked by one or many. The various parts of the maize-plant are subject to the attack of at least seventy species of fungi; the common tulip-tree, or yellow poplar, is reported as the host of nearly one hundred species; the oat-plant has a dozen such enemies, and so on. The annual loss at
tributed to the attacks of fungi, to which the re duced yield and inferior quality of the product are largely due, amounts to hundreds of millions of dollars. It has been estimated that the average lass due to oat-smut in the United States alone amounts to more than $18,000,000 annually. If to this sum be added the similar losses of other great economic crops, the total would be enor mous. • Cereal rusts in the United States are believed to cause more loss than any other source of injury, and often the loss amounts to more than the damage done by all other enemies, fungous and insect, added together. In certain localities the grape crops have been almost wholly destroyed by parasitic fungi, and certain truck crops have suffered similarly. The great famine in Ireland during 1846-47 has been largely at tributed to the almost total destruction of the potato crop, through the attack of the potato rot (Phytophthora infestans) The general classification of the fungi, aside from the Myxomycetes and the Bacteria, some of which ate of great economic importance, is di vided into four main groups: (1) The Phyco inycetes, which include the water-molds destruc tive to young fish; the well-known fly-fungus, by which flies are often fixed to window-panes, par ticularly in the autumn; the black mold of food stuffs, manure heaps, etc.; the downy mildews, as the potato rot, peronospora of grape, etc. (2) The Ascomyeetes, or sac-fungi. which include the powdery mildews of grape, gooseberry, cherry; the blue molds, the black knot of plums, ergot of rye, peach leaf-curl, the black wart-like growths on many trees; the cup fungi, so called from the shape of their fruiting organs, etc. (3) The 2Ecidiomycetes, which include the rusts and smuts of various plants. (4) The Basidio inycetes, which embrace the mushrooms, toad stools, coral fungi, shelf fungi, etc. From an economic standpoint the parasitic species of the second and third groups are of the greatest im portance. Fortunately, many of the diseases caused by these parasites may be prevented by the adoption of certain precautionary measures, by the application of a fungicide (q.v.), and by the exercise of proper methods of cultivation by which the general vigor of the plant is improved. See DISEASES OF PLANTS; also diseases of spe cific crops: e.g. APPLE; GRAPE; POTATO; WHEAT; OATS; CORN, etc.