Pathogen 

• Thanatephorus (Rhizoctonia solani)

Hosts

The disease is known to affect all the major cereals crops and probably most grasses. Barley is much more susceptible to the disease than other cereals.

Symptoms

The disease is usually apparent as patches of thin stunted plants, which often show yellowing or purpling with die-back of seedlings in the autumn. Patches may also become visible in early spring as areas of stunted purpled plants. The root systems of plants within these patches are usually poor and branched. Points of brown rotten tissue may be seen at intervals along the length of the root where they appear as constrictions (actually the result of rotting of the cortex), often giving the root the appearance of a string of sausages. Affected plants remain thin and stunted throughout the season and their maturity is often delayed. Affected crops are usually confined to sandy loam or loamy sands, in areas such as the Brecklands of Norfolk or Suffolk.

Life cycle

The disease is soil-borne. The fungus is very common in soils and can survive between susceptible crops as mycelium on dead tissues and other hosts.

Importance

The disease is erratic in occurrence and frequently more severe where crops have been established by direct drilling or minimum cultivations. Individual crops may suffer significant losses but in general wheat is not seriously affected. Losses in barley can be much more significant.