False Smut Control

Symptoms

False smut is caused by the fungus Ustilaginoidea virens. It appears only at the grain stage, when individual grains in the panicle are replaced by velvety spore balls. The balls are small at first, orange to yellow, then enlarge and turn greenish to dark green or almost black with a powdery surface. Usually only a few grains per panicle are affected, but they are very visible and the spore powder can soil other grains.

Damage

Affected grains are lost and the spore powder can reduce the quality and market value of the harvested grain. Direct yield loss is usually low to moderate, but the disease is increasing in India with high yielding varieties, dense planting and high nitrogen. Some grain discolouration and possible toxins make heavily smutted produce less acceptable.

Organic & cultural control

Use clean, healthy seed and avoid seed from smutted fields. Grow less susceptible varieties and avoid excess nitrogen, especially late top dressing. Avoid very dense planting. Remove and destroy smut balls and infected panicles to reduce spore load. Deep ploughing and removing crop residue help reduce carryover spores in the soil.

Chemical control

False smut is best managed by prevention because it shows after grains form. Where the disease is regular, a protective fungicide spray such as propiconazole, a copper based fungicide, or azoxystrobin plus tebuconazole is recommended at the boot stage just before panicle emergence, since spraying after spore balls appear is largely ineffective. Always follow the product label dose, observe the pre-harvest interval, and consult your local KVK or agronomist before spraying.

Always follow the product label, the recommended pre-harvest interval, and your local KVK or agronomist. Pesticide approvals change, so verify before use.

Prevention

Use clean seed and less susceptible varieties, avoid excess and late nitrogen, avoid dense planting, and remove and destroy smut balls. If the disease recurs, plan a protective fungicide spray at the boot stage rather than waiting for symptoms. Deep ploughing reduces soil spore load.