Cotton aphids (Aphis gossypii)
The cotton aphid (Aphis gossypii), has been identified as one of the major pest problems of okra in Kenya. They cause damage by sucking plant sap weakening the plants, and by excreting a sticky substance (honeydew), which results in growth of sooty mould affecting photosynthesis. Contamination of pods with aphids, aphid skins, honeydew and/ or sooty mould may result in their rejection in the market.
The cotton aphid transmits the Yellow Vein Mosaic Virus in okra. Cotton aphid (Aphis gossypii) is a small aphid. Adults range from just under 1-1.5 mm in body length.
- Conserve natural enemies. Parasitic wasps and predatory insects, including lady bird beetles, damsel bugs, lacewings, and hover fly larvae are important in natural control of aphids. Link to natural enemies datasheet.
- Use reflective mulches. Reflective aluminium mulches deter aphids from landing on plants. The effect is lost once plants are large enough to cover the mulch.
- Monitor the crop regularly.
- If necessary, spray with botanicals (e.g. neem extracts). Experiments in Kenya showed that neem-based pesticides, namely Achook ( Azadirachtin 15% w/w ) and a neem extract ( Azadirachtin 0.6 w/w ) effectively controlled the cotton aphid giving protection to the crop for the whole season. Yield of plants treated with these two products was similar, but using Achook was much economic that using the neem extract (Malenge, 2005).
- Spray only attacked plants (spot spraying).