Anthracnose

Colletotrichum graminicola

Biology

Anthracnose attacks cereals and grasses. This disease is not common in Canada, but it does occur on oats in north-central and western Alberta. It infects all parts of the plant.

Spores of this fungus overwinter on the seed and crop residue. Initial infections usually result from soil-borne inoculum. Upper plant parts are usually infected later in the season from spores spread by splashing rain or wind.

Spore production is favoured by poor soils, high pH and wet weather. Crops that are nutritionally stressed are especially susceptible.

Damage Description

Brown lens-shaped spots appear on the leaves of oats. Crown and lower stem areas become bleached and then turn brown. Small black dots, which are sexual fruiting bodies, are produced on dead tissue.

Crown infections reduce plant vigor and cause premature ripening. There is also increased lodging caused by constrictions at the base of the tillers. This disease is generally of little economic significance in the prairie provinces.

Diagnosis

Take representative soil samples at 0-15 cm below ground level throughout the field and have them checked for
pH and fertility.

Management Strategy

Reduce spore levels and promote an environment unfavorable to the pathogen.

• Maintain soil fertility with recommended levels of fertilizer and rotations that improve the soil.
• Do not use cereals in crop rotation for at least two years.
• Control grassy weeds as well as headland grasses.
• Turn under crop residue to reduce spore levels.
• Do not grow oats on soils with a high pH.