Yields are reduced because affected roots are less efficient at taking up water and nutrients, so tap roots can become malformed.
A recent supply problem with one of the industry's widely used nematicides is a timely reminder of just how vulnerable carrot and parsnip growers are when it comes to controlling nematodes.
There is a lack of proven alternative crop-protection products but other strategies, such as longer rotations, are hampered by a shortage of suitable land and the industry's reliance on rented sites.
A review Dr Roy Neilson, a nematologist at the James Hutton Institute, has highlighted action that agronomists and growers can take in the short-to-medium term, such as cultivation, rotation and monitoring, to help improve management of FLNs.
The review recommends that further research now needs to be done to develop longer-term management strategies, including, resistance breeding, biological control, cover crops and biofumigation.
- Increase length of rotation between carrot and parsnip crops - ideally around seven years.
- Exclude from rotation crops that can maintain or increase FLNs, including sugar beet, potato, peas and beans.
- Monitor FLNs with best-practice soil testing.
- Consider cover crops within standard rotations.
A new fact sheet is available to help growers manage FLNs associated with carrots and parsnips.