The Russian wheat aphid is a serious pest of wheat and barley causing yield losses of between 20 to 100 per cent in affected crops.
The aphid originated in Russia and was first recorded in Kenya in 1995 according to the Kenya Agricultural and Livestock Research Organization (KALRO). It has since been affecting farmers’ crops in Nakuru, Eldoret, Kitale, East and West Mau escarpment, Nyandarua, Timau, and Maralal.
The initial symptom of the disease is moderate yellowing of the wheat/barley with the crop appearing to be under drought duress even when there is no drought. The aphid causes the leaves to curl as the pest lives inside the tightly rolled leaves stunting the crop in the process.
Farmers can control the pest through chemical control either by applying systemic insecticides on seeds at planting or foliar fertilisers on the leaves.
The chemical applied with the seed at planting is Gaucho 350 FS at the rate of 200ml per 100kg of seed or Carbofuran 350 ST at the rate of 750ml per 100kg of seed.
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Foliar fertlisers are applied when damage signs on the leaves are noticed with one spray recommended.
Foliar fertilisers to be applied are Acozord (750ml/ha, Metasystox (500ml/ha), or Dimecron (800ml/ha).
Farmers can also embrace cultural control by increasing plant density using as low plant densities are prone to attack by the pest. Remove volunteer plants such as grasses that act as hosts for the pests even before the crop is planted.
According to KNBS, Kenyans consume an estimated one million tonnes of wheat annually with the crop being the second most important cereal grain after maize in Kenya.