The fungus Cochliobolus sativus is the teleomorph (sexual stage) of Bipolaris sorokiniana (anamorph) which is the causal agent of a wide variety of cereal diseases. The pathogen can infect and cause disease on roots (where it is known as common root rot), leaf and stem, and head tissue. C. sativus is extremely rare in nature and thus it is the asexual or anamorphic stage which causes infections. The two most common diseases caused by B. sorokiniana are spot blotch and common root rot, mainly on wheat and barley crops.

Identification

The mycelium of B. sorokiniana is usually deep olive-brown. New cultures produce abundant simple conidiophores, which may be single or clustered and measure 6–10 x 110–220 μm with septations. Conidia develop laterally from pores beneath each conidiophore septum. Conidia are olive-brown and ovate to oblong, with rounded ends and a prominent basal scar. They measure 15–28 x 40–120 μm and are 3- to 10-septate. Some may be slightly curved. Their walls are smooth and noticeably thickened at the septa. The sexual state (C. sativus), when formed in culture, is in the form of black, globose pseudothecia 300–400 μm in diameter, with erect beaks 50–200 μm long. Asci are clavate and measure 20–35 x 150–250 μm. Ascospores are hyaline, uniformly filamentous, and spirally flexed within asci. They measure 5–10 x 200–250 μm and are 4- to 10-septate.

Host species

''Agropyron cristatum1, Allium sp. 1, Alopecurus pratensis1, Aneurolepidium chinense1, Avena sativa1'' Bromus inermis1, B. marginatus1, B. willdenowii1 Calluna vulgaris1, Chloris gayana1, Cicer arietinum1, Clinelymus dahuricus1, C. sibiricus1, Cynodon dactylon1, C. transvaalensis1 Dactylis glomerata1 Echinochloa crus-galli1, Elymus junceus1 ''Festuca sp. 1'' ''Guzmania sp. 1'' ''Hordeum brevisubulatum1, H. distichon1, H. sativum var. hexastichon1, H. vulgare1, H. vulgare var. hexastichon1'' Lablab purpureus1, Linum usitatissimum1, Lolium multiflorum1 Pennisetum typhoides1 Roegneria semicostata1 ''Saccharum sp. 1, Secale cereale1, Setaria italica1, Sorghum sp. 1'' ''Taraxacum kok-saghyz1, Trisetum aestivum1, Triticum aestivum1, T. secale1, T. turgidum subsp. durum, T. vulgare1'' Zea mays1

Geographical distribution

Cochliobolus sativus has a world-wide distribution.

Main diseases

Common root rot (barley); Common root rot (wheat); spot blotch (barley); Spot blotch (wheat)

Spot blotch of wheat

This is most important disease in non-tradition wheat growing areas. The B. sorokiniana comes with Pyrenophora tritici-repentis and causes millions of tons of wheat loss each year. The symptoms are blotch as well as induced senescence due to premature chlorophyll losses Rosyara et al., 2007.