Fall armyworm (Spodoptera frugiperda) has become one of the most devastating pests affecting maize production in Zimbabwe since its arrival in 2016. Here is what every farmer needs to know about identification, prevention, and control.
Identification
Fall armyworm larvae are greenish-brown caterpillars with a distinctive inverted Y-shaped marking on the head. They feed inside the whorl of the maize plant, producing large amounts of frass (sawdust-like droppings). Damage appears as ragged holes in leaves and destruction of the growing point.
Scouting
Start scouting your maize fields from 2 weeks after emergence. Check at least 20 plants across the field in a W-pattern. If more than 5% of plants show fresh damage with live larvae, intervention is needed.
Control Options
Cultural Control
- Plant early within the recommended window to avoid peak moth flights
- Use push-pull technology where feasible (intercrop with Desmodium, border with Napier grass)
- Practise crop rotation with non-host crops
- Destroy crop residues after harvest if infestation was heavy
Biological Control
- Encourage natural enemies: parasitic wasps, predatory beetles, birds
- Apply Bacillus thuringiensis (Bt) biological insecticide on young larvae
Chemical Control
- Apply registered insecticides when the economic threshold is exceeded
- Target applications into the whorl where larvae feed
- Rotate chemical groups to prevent resistance build-up
- Always follow label instructions and observe withholding periods
Need help with pest management on your farm? Book a field visit and we will develop an integrated pest management plan for your situation.