Common bunt, also known as hill bunt, Indian bunt European bunt, stinking smut or covered smut, is a disease of both spring and winter

wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...

s. It is caused by two very closely related fungi, ''

Tilletia tritici ''Tilletia tritici'' is the causal agent of common bunt of wheat. Morphology Teliopsores are thick-walled, globiose, reticulate and 13–23 μm in diameter. Use as a biological weapon It was used as a biological weapon by Iraq against I ...

'' (syn. ''

Tilletia caries ''Tilletia caries'' (synonymous with ''Tilletia tritici'') is a basidiomycete that causes common bunt of wheat. The common names of this disease are stinking bunt of wheat and stinking smut of wheat. This pathogen infects wheat, rye, and various ...

'') and '' T. laevis'' (syn. ''T. foetida'').

Symptoms

Plants with common bunt may be moderately stunted but infected plants cannot be easily recognized until near maturity and even then it is seldom conspicuous. After initial infection, the entire kernel is converted into a sorus consisting of a dark brown to black mass of teliospores covered by a modified periderm, which is thin and papery. The sorus is light to dark brown and is called a bunt ball. The bunt balls resemble wheat kernels but tend to be more spherical. The bunted heads are slender, bluish-green and may stay greener longer than healthy heads. The bunt balls change to a dull gray-brown at maturity, at which they become conspicuous. The fragile covering of the bunt balls are ruptured at harvest, producing clouds of spores. The spores have a fishy odor. Intact sori can also be found among harvested grain.

Disease cycle

Millions of spores are released at harvest and contaminate healthy kernels or land on other plant parts or the soil. The spores persist on the contaminated kernels or in the soil. The disease is initiated when soil-borne, or in particular seed-borne, teliospores germinate in response to moisture and produce hyphae that infect germinating seeds by penetrating the coleoptile before plants emerge. Cool soil temperatures (5° to 10 °C) favor infection. The intercellular hyphae become established in the apical

meristem The meristem is a type of tissue found in plants. It consists of undifferentiated cells (meristematic cells) capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants. These cells conti ...

and are maintained systemically within the plant. After initial infection, hyphae are sparse in plants. The fungus proliferates in the spikes when ovaries begin to form. Sporulation occurs in endosperm tissue until the entire kernel is converted into a

sorus A sorus (pl. sori) is a cluster of sporangia (structures producing and containing spores) in ferns and fungi. A coenosorus (plural coenosori) is a compound sorus composed of multiple, fused sori. Etymology This New Latin word is from Ancient Gr ...

consisting of a dark brown to black mass of teliospores covered by a modified periderm, which is thin and papery.

Pathotypes

Well-defined pathogenic races have been found among the bunt population, and the classic gene-for-gene relationship is present between the fungus and host.

Management

Control of common bunt includes using clean seed, seed treatments chemicals and resistant cultivars. Historically, seed treatment with organomercury fungicides reduced common bunt to manageable levels. Systemic seed treatment fungicides include carboxin, difenoconazole, triadimenol and others and are highly effective. However, in Australia and Greece, strains of ''T. laevis'' have developed resistance to polychlorobenzene fungicides.

References

External links