Rhizoctonia stunt symptoms and risk in cereals

Found in soils and crops worldwide, this pathogen is associated with establishment losses and stunted plants. Learn about rhizoctonia’s life cycle and the factors that influence risk to cereals.

Thanatephorus cucumeris (Rhizoctonia solani) is a common soilborne crop pathogen.

It can infect cereals (wheat, barley, oats, rye and triticale), in addition to oilseed rape, broccoli, cabbage, cauliflower, peas, beans, radish, potatoes and many grass-weed species.

The pathogen survives between susceptible crops as mycelium on dead tissues and other hosts.

In autumn and spring, pathogen sclerotia germinate, producing hyphae that infect roots.

Infection is usually apparent as thin patches in the crop, due to the death of seedlings.

In early spring, infected patches often contain thin and stunted yellowed/purpled plants.

The root systems of plants within these patches are usually poor and branched.

Brown, rotten tissue may be seen as constrictions at intervals along the length of the root – often giving the root the appearance of a string of sausages.

In infected crops, maturity is often delayed.

• The disease occurs erratically in cereals
• Barley is much more susceptible than other cereals
• Individual crops may suffer considerable losses
• It is usually confined to sandy loam or loamy sands
• It is more severe where crops have been established by direct drilling or minimum cultivation