Cochliobolus sativus (Ito & Kuribayashi) Drechs. Ex Dast. [teleomorph]
Bipolaris sorokinana (Sacc.) Shoemaker
In many areas, this disease may be associated with Fusarium spp. – See Crown Rot
- Symptoms: These fungi produce a darkening or browning of the subcrown internode, coleoptile and leaf sheaths (picture at left). Brown streaks may also appear on the basal internode of tillers. The fungi commonly will cause reduced tillering, and slight root rotting has been known to occur. Individual plants or groups of plants may lodge. Unlike crown rot, however, common root rot will not cause “whiteheads,” or prematurely white spikes to occur. Infection early in the crop development can cause pre- or post-emergence "damping off" of seedlings (picture at right). Since each fungus can attack a different plant part at a different growth stage, positive field identification of the causal agent is difficult.
- Development: The roots or crown tissues are infected by conidia or mycelia present on crop debris. Infection by and development of common root rot is favored by warm, dry soils when the plants are under stress.
- Hosts/Distribution: These diseases affect all major small grain cereals grown in the temperate regions of the world.
- Importance: Major epidemics have not been reported. However, localized losses can result from thinned stands, a decrease in the number of tillers, and from reductions in spike size and test weights.
Reference:
- Dr. Graham B. Wildermuth- Senior Plant Pathologist (now retired).