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smut,name for an order of parasitic fungi (Ustilaginales) and the various diseases of plantsdiseases of plants.
Most plant diseases are caused by fungi, bacteria, and viruses. Although the term disease is usually used only for the destruction of live plants, the action of dry rot and the rotting of harvested crops in storage or transport is similar to the rots
..... Click the link for more information. caused by them. Smuts produce sootlike masses of spores on the host. The spore masses may break up into a dustlike powder readily scattered by wind (loose smuts) or remain more or less covered by a smooth membrane (covered or kernel smuts). Certain smuts are edible and are considered a delicacy in some countries. As a disease, smuts lower the vitality of the host plant and often cause deformities. There is no alternation of hosts. Smuts are a most serious threat to cereal grain crops. Among those that cause severe annual losses to crops are corn smut, oat smut, bunt or stinking smut, and loose smut of wheat. Bunt is probably the most serious disease that attacks wheat at the young or seedling stage and spoils the grain. It has the odor of sour herring and is caused by either of two smut fungi. The fungus may be present on the wheat seed or in the soil in which the seed is sown, or it may be blown into a field by the wind. Smuts are classified in the kingdom FungiFungi
, kingdom of heterotrophic single-celled, multinucleated, or multicellular organisms, including yeasts, molds, and mushrooms. The organisms live as parasites, symbionts, or saprobes (see saprophyte).
..... Click the link for more information. , phylum (division) Basidiomycota, order Ustilaginales.
The dark powdery masses of “smut spores” (teliospores) that develop in living plant tissues infected by species of Ustilago, Tilletia, and similar plant parasitic fungi. Molecular and ultrastructural data show that smut fungi comprise two phylogenetically distinct lines within the Basidiomycota; recent classification places them in two different classes, Ustilaginomycetes and Urediniomycetes. Ustilaginomycetes contains most of the smut fungi, and several groups of morphologically distinct, nonsmut plant parasites, including Exobasidium, Graphiola, and Microstroma. Smut fungi belonging to the genus Microbotryum, best known as anther smuts of Caryophyllaceae, are now placed within the Urediniomycetes with rust fungi and allied taxa. Ustilaginomycetes and Urediniomycetes also contain a number of saprotrophic, yeastlike fungi that are related to the plant parasitic smuts. Yeastlike saprotrophs that produce teliospores include Tilletiaria in the Ustilaginomycetes, and Leucosporidium, Rhodosporidium, and Sporobolomyces in the Urediniomycetes. Yeastlike saprotrophs in the Ustilaginomycetes that do not form teliospores but reproduce in another manner similar to Ustilago and Tilletia include Pseudozyma and Tilletiopsis, respectively. See Fungi
Teliospores of plant parasitic smut fungi form in a fruiting structure called a sorus. Sori are commonly produced in the inflorescence, leaves, or stems of the host, although the root is the site of sorus formation in smuts belonging to the genus Entorrhiza. Teliospores develop within the sorus by conversion of dikaryotic mycelial cells into thick-walled resistant spores within which paired nuclei fuse. Meiosis also occurs in teliospores of some smut fungi, but meiotic division is more characteristic of the tubular basidium that develops at germination.
There are 1200 species and 50 different genera of known smut fungi that infect over 4000 species of angiosperms. Smut fungi occur on both monocotyledonous and dicotyledonous hosts but are most economically important as pathogens of barley, corn, oats, onions, rice, sorghum, sugarcane, and wheat. Control of smut diseases varies with species and includes fungicidal seed treatments and use of resistant crop varieties. See Basidiomycota, Plant pathology
a widespread plant disease caused by smut fungi (order Ustilaginales). The chief losses by smut occur in grain crops, thus causing great economic loss. Grain losses were especially bad in prerevolutionary Russia; this has been greatly reduced in the USSR, but losses caused by smut are still great. Smut also attacks plants of the families Liliaceae, Caryophyllaceae, Polygonaceae, Compositae, Umbelliferae, and Papaveraceae. It destroys, completely or partially, a number of organs, primarily the gynoecia, spikes, panicles, and spadices, but also the stems, leaves, and crowns. All of these organs are turned into dark masses of spores. Smut spores are specialized parasites; each species is adapted to a specific plant species.
There are several harmful smuts. In covered wheat and rye smut the parasite destroys the germs and is preserved in the form of smut sacks, or individual spores scattered on the seeds. In barley rock smut and covered oat smut the spores fill the gynoecia without destroying the panicles or spikes, and a flat black mass of spores can be seen through the spike coatings. In loose wheat and corn smut the parasite destroys the spikes, panicles, and spadices, turning them into a black dusty mass. Stem smut of rye and wheat infects the stems and part of the leaves; blister corn smut forms on various parts of the plant, leaving tumors covered with a coating and filled with spores. Smut fungi are also parasites on other grains, such as rice, foxtail millet, Italian and Japanese millet, and sorghum. Another type of smut worth noting is onion smut, which destroys onions. Some species infest plants in the soil, usually before the appearance of sprouts (covered wheat smut, rice stem smut, and others). Others attack during heading or flowering (loose wheat smut and loose barley smut), and still others infect young and tender tissues during the entire vegetation period (onion smut and blister corn smut). Countermeasures taken against smut include the use of resistant species; intensive agricultural technological measures assuring the growth of resistant and healthy plants; the culling of seed plantings heavily infested with smut; the cleaning and disinfection of seeds with chemical preparations or by thermal means; and the warm-air or sun heating of seeds.
REFERENCESUl’ianishchev, V. I. Mikroflora Azerbaidzhana. Vol. 1: Golovnevye griby. Baku, 1952.
Kalashnikov, K. Ia. Golovnia zernovykh kul’tur. Leningrad-Moscow, 1962.
Slovar’-spravochnik fitopatologa, 2nd ed. Edited by P. N. Golovin. Leningrad, 1967.
K. IA. KALASHNIKOV