smut (redirected from smuttiness)

smut, name for an order of parasitic fungi (Ustilaginales) and the various diseases of plants 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 Fungi, phylum (division) Basidiomycota, order Ustilaginales.

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smut

Disease of cereals, corn, grasses, onion, and sorghum, caused by many species of fungi (see fungus). Spores accumulate in sootlike masses (sori) that form within blisters in seeds, leaves, stems, flower parts, and bulbs. The sori usually break up into a black powder that is readily dispersed by wind. Many smut fungi enter embryos or seedling plants, develop throughout the plant, and appear externally only as the plants near maturity. Other smuts are localized, infecting actively growing tissues. Control includes growing resistant varieties in noninfested soil, treating seeds with fungicide, using disease-free transplants, and destroying infected plants or plant parts before the spores are released.

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smut

Angling a minute midge or other insect relished by trout

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smut [smət]

(metallurgy)

A reaction product left on the surface of a metal after pickling.

(plant pathology)

Any of various destructive fungus diseases of cereals and other plants characterized by large dusty masses of dark spores on the plant organs.

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Smut (microbiology)

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