Weeds, Insects & Diseases

Common root rot [Cochliobolus sativus]


Disease Biology

The fungi causing common root rot overwinter on crop residue and spores survive for many years in soil, so the disease is widespread. The disease can be seed-borne and cause seedling blight. C. sativus also causes spot blotch and kernel smud...


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Damage Description

Brown lesions occur initially on coleoptiles and later on lower leaf sheaths in the crown area and on roots. No above-ground symptoms may be evident but occasionally scattered plants ripen and die prematurely. These plants usually have brown lesion...


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Management

Dry and warm soil conditions are important for infection. Plants under nutritional stress are also vulnerable to attack.

Allow several years between susceptible crops. Plant resistant varieties. Avoid deep seeding which increases disease se...


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Description

The fungi causing common root rot overwinter on crop residue and spores survive for many years in soil, so the disease is widespread. The disease can be seed-borne and cause seedling blight. C. sativus also causes spot blotch and kernel smudge (black point).

Dry and warm soil conditions are important for infection. Plants under nutritional stress are also vulnerable to attack.

  • Common Root Rot
  • Common Root Rot

Damage Description

Brown lesions occur initially on coleoptiles and later on lower leaf sheaths in the crown area and on roots. No above-ground symptoms may be evident but occasionally scattered plants ripen and die prematurely. These plants usually have brown lesions extending up the stem above ground but are not easily pulled compared to those affected by take-all.

Symptoms occur on plants scattered throughout the field. When infection is very severe, young seedlings are killed outright. Less severe cases, as a result of later infection, can weaken plants and impact viability of tillers resulting in reduced yields.

    Management

    Dry and warm soil conditions are important for infection. Plants under nutritional stress are also vulnerable to attack.

    Allow several years between susceptible crops. Plant resistant varieties. Avoid deep seeding which increases disease severity, and maintain adequate fertility levels. Minimum tillage may reduce common root rot. Seed treatments control seeding blight but usually will not fully protect plants beyond the seedling stage.