Growers looking to manage the risks of nematode-related damage in their root crops can try an alternative to nematicides by growing a nematode-resistant cover crop.

Certain plant crops and varieties have now been bred with resistance to specific nematodes and can be used to reduce populations of this pest, explains Nickerson’s Alastair Moore.

Mr Moore says one of the main problems with nematodes is the damage they create, such as stunted plants, leaf discolouration and root distortion. However, when symptoms arise Mr Moore recommends growers take a soil sample and haved it tested to identify the exact cause of damage.

“This will also identify the type of nematode as there are many different species which can be present in any soils. Once the nematode species has been determined, the appropriate resistant cover crop can be sown.”

Mr Moore says crops such as Doublet oilseed radish or white mustard Smash essentially stop nematode reproduction by stimulating the hatching process, so the larvae respond to the cover crop as if it is a host plant.

“Because the plant is resistant, the nematode has no food source when it hatches and is therefore unable to develop into a female. It then either turns into a male, or dies, thus breaking the life-cycle and reducing the population,” he says.

“The oilseed radish has been specifically bred to reduce nematode populations and can be sown from July until the end of August. Whereas the white mustard which is very fast growing can be sown from July until early September. It can also help reduce Rhizoctonia infection,” he says.

“Deciding whether to grow oilseed radish or the white mustard depends on which species of nematode are present, and which crops make up the existing rotation. Usually resistant cover crops are planted after the cereal harvest, and incorporated into the soil before the following root crop is drilled in the spring.

“Cover crops are best included as part of an integrated crop rotation approach. When combined with regular machinery cleaning and control of plant material cross contamination, the nematode population can be kept under control for 3-4 years.”

These integrated methods are very popular in Germany, France and Belgium where they have been used successfully for many years.

“Provided the cover crop is sown promptly after the cereal harvest this will enable it to establish successfully and reach the appropriate maturity stage prior to incorporation.”

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