nematode control

Nematode control in your organic garden

Nematode control is a common challenge of organic gardeners. There are a large variety of nematodes that are helpful for the garden, but its the root knot nematode that causes grief and demands nematode control if you want a healthy and productive garden.

Nematodes are microscopic, long, thin worms that cause stunted and unproductive plants. The image above shows a bean plant with nematode infestation. As you can see, the nematodes have burrowed into the roots and caused knotty lumps. Root knot nematodes infest a wide range of common vegetable crops such as: potatoes, eggplant, capsicums, tomatoes,carrots, lettuce, parsley, cucumbers, melons and zucchini.

Nematode control methods

These nematode control methods all relate to management of your patch with organic methods and are not magic potions that will kill nematodes if you find them in your wilted plants. So its important to be patient and diligent with these methods:

  1. Use consistent practices of building soil life, as the micro-organisms in the soil are likely to be predators or parasites of root knot nematodes. All the usual ways of building a healthy soil such as adding adding compost, mulching and green manuring will improve nematode control. We enhance our soil life processes with biodynamic preparations.
  2. Grow a green manure crop specifically for nematode control as there are plants that will decompose into the soil and release a nematode killing gas. Ideal plants are: rapeseed (canola), Brassica napus, BQ Mulch, marigolds and Indian mustard. BQ Mulch, canola, Brassicas and mustard are cool season crops. Marigold is a warm season crop that when mixed with cowpea makes an effective, warm season, nematode-controlling green manure. I normally buy these seeds from Green Harvest.
  3. Use crop rotation incorporating crops that will not host nematodes such as: cowpea, soybean, oats, wheat and woolly pod vetch. A rotation of 2 years or more between susceptible crops is needed to control a serious nematode outbreak.
  4. Grow vegetable crops that are more resistant to nematodes such as: broccoli, corn, brussel sprouts, chives, leeks and spring onions.
  5. Practice good hygiene in the garden to help limit the spread of nematodes. When harvesting nematode infected plants, remove as much infected root from the soil as possible and dispose of it well away from food garden areas. I normally burn them.

Learning about appropriate management techniques for your garden is taught at our workshops and our next organic and biodynamic workshops is on our event calendar here. Our mentoring service will also guide you in managing your soil for nematode control.

Happy gardening

Peter Kearney –


Posted in biodynamic gardening, Mentoring, Seasonal tips, urban agriculture, urban farming, vegetable gardening and tagged , , , , , , , , , , .


  1. Thanks for all this very valuable information Peter.
    We have the green manure crop growing well and looking to start a crop in March/April so may get you back around there if possible mate.

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