Wildflowers Could Cut Aphid-spread Viruses in Potatoes
Wildflowers grown in strips through potato crops could control disease-carrying aphids and may help growers faced with a dwindling number of insecticides, reports Farmers Weekly. Areas of wildflowers grown in the headlands and between tramlines of crops have been shown to attract the natural enemies of aphids – namely hoverflies, lacewings and ladybirds.
Scottish Agronomy, the crop consultant group, has been trialing this technique to help growers cope with the banning of some insecticides and increased aphid resistance to others. The level of the main damaging potato virus Y, strain N (PVYn), is now at the highest level in seed potato crops in 20 years, highlighting the need for new methods of aphid control.
Eric Anderson, senior agronomist at the group, said both ware and seed potato producers are looking ahead to when fewer effective insecticides are likely to be available.
“The vision is to cut back on insecticides and growers recognize that some insecticides will not be available in the long term,” he says.
Anderson has trialed the technique of growing wild flower mixes on the headlands, either in 3m strips every tramline width or every other tramline width. This creates corridors through the crop and more diversity, in a move away from a more monoculture system with its high reliance on chemical controls.
Anderson’s work has identified species such as cornflower, common vetch and yarrow as good homes for aphid enemies to be reared, and these wild flowers are at a low growing height to fit in with the potato crops. He is still refining which species should be sown and sowing dates, and hopes this may allow growers to cut back on their insecticide use in the future.
The potential virus problem in potatoes is further exacerbated by the withdrawal of diquat (Reglone) as a desiccant. This means that crop haulm stays greener for longer, so is more at risk from regrowth and late season aphid-spread viruses.
Anderson points out that there can be a lag period until natural enemies have time to build up their numbers. Therefore, there is potential for integrated pest management (IPM) using both traditional and modern tools to control aphids. This approach is being investigated at the AHDB seed potato farm at Morphie, north of Montrose, and it is hoped the wider adoption of IPM will improve PVYn control while reducing insecticide use.