''Sarocladium oryzae'' (Sawada) is a plant pathogen causing the of

rice Rice is a cereal grain and in its Domestication, domesticated form is the staple food of over half of the world's population, particularly in Asia and Africa. Rice is the seed of the grass species ''Oryza sativa'' (Asian rice)—or, much l ...

and of

Bambusoideae Bamboos are a diverse group of mostly evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family, in the case of '' Dendrocalamus sinicus'' ...

spp. in

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

Taxonomy and morphology

''Sarocladium oryzae'' has

conidiophore A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an Asexual reproduction, asexual, non-motility, motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word f ...

s which are irregularly penicillate and slimy, 1-celled

conidia A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an asexual, non- motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also ...

. It was previously known as ''Acrocylindrium oryzae''. For forty years prior to 2005, the industrial strain used to manufacture the antibiotic cerulenin was known under the invalidly published name "'' Cephalosporium caerulens''", but a subculture of the original ''C. caerulens'' strain KF-140 was subsequently shown to be conspecific with ''S. oryzae''.

Physiology and metabolites

In axenic culture, ''S. oryzae'' produces 0.3–0.627

microgram In the metric system, a microgram or microgramme is a unit of mass equal to one millionth () of a gram. The unit symbol is μg according to the International System of Units (SI); the recommended symbol in the United States and United Kingdom wh ...

s of helvolic acid and 0.9–4.8 micrograms of cerulenin per milliliter of culture medium. : : : : :These reviews cite this research. : : The level of helvolic acid correlated with a higher incidence of sheath rot disease. Rice grains from infected plants were found to contain 2.2 micrograms helvolic acid and 1.75 micrograms of cerulein per gram of infected seeds, which induce

chlorosis In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll. As chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to ...

and reduce the seed viability and seedling health.

Plant disease symptoms

The disease is found in rice plants usually injured by insects or other diseases. Hot () and humid (wet) weather favour the disease. It is also associated with virus-infected plants. Early symptoms are oblong to irregular spots, with gray centers and brown margins. Spots or rotting occur on the leaf sheath that encloses the young panicles. There is discoloration in the sheath. In severe infection, all or part of the young panicles do not emerge and remain within the sheath. Unemerged panicles will soon rot and produce powdery fungus growth inside the leaf sheath. Infection occurs on the uppermost leaf sheath at all stages, but is most damaging when it occurs at late booting stage.

Management

Partners of the

CABI CABI (in various spellings) is an abbreviation that may refer to: * Centre for Agriculture and Bioscience International (CABI, sometimes also referred to as CAB International), a UK-based nonprofit inter-governmental organisation for scientific res ...

-led programme, Plantwise including the General Directorate of Agriculture in Cambodia have suggested reducing the density of planted crops to and removing infected stubble and weeds from the field. They also recommend application of fertilisers including potassium,

calcium sulphate Calcium sulfate (or calcium sulphate) is an Inorganic compound, inorganic Salt (chemistry), salt with the chemical formula . It occurs in several Hydrate, hydrated forms; the anhydrous state (known as anhydrite) is a white crystalline solid often ...

and zinc sulphate during the tillering stage to strengthen the stem and leaf tissues. The Bureau of Rice Research and Development, Rice Department, of Thailand recommends using disease-free seeds and plants, avoiding monocropping with any one variety of rice (planting at least two varieties in the same field), and regular monitoring of fields.

Sources

References

External links

* (includes photo of sheath rot) Fungal plant pathogens and diseases Rice diseases Enigmatic Ascomycota taxa Fungus species {{plant-disease-stub