Nematodes, or ‘eelworms’, are small, non-segmented worms that live in soil, which cannot be seen with the naked eye. They are only 50 microns in diameter and about 1 mm long or less. They feed on fungi, bacteria, and other soil organisms, together with plant cells. In some cases, they also allow fungal rots to enter that destroy the roots. While most nematode species have a beneficial role in the soil, some species are pests and impact agricultural production.
Nematodes can be differentiated by their feeding type or mouthparts. While bacterial feeding nematodes have a tube-like structure to suck bacteria, fungal feeding nematodes have a piercing needle (stylet), which penetrates fungal cells and enables the nematode to suck cell contents. Root feeding (parasitic) nematodes, such as the root knot nematode, also have piercing mouthpart to pierce root cells. Predators feed on other nematodes and small soil organisms.
Parasitic nematodes are pests because they feed on plant roots and slow plant growth. Species such as stem and bulb nematode also migrate to above ground plant parts. Beneficial nematodes attack and kill a range of pests such as borers, grubs, thrips and beetles, with negligible effects on non-target species. Nematodes are found in the top few centimetres of the soil, living in the thin films of water surrounding soil particles.
Preferred conditions /survival
Host vegetable crops
|Potato cyst nematode (Globodera rostochiensis)||PCN cysts can remain dormant in the soil for up to 30 years. The optimum soil temperature is 15-20°C.||Plants of the Solanaceae family (e.g. potato; eggplant; tomato).||Appearance of round pinhead sized white to golden cysts on the roots of infested plant at the time of flowering. Plants show yellowing and wilting.|
|Root-knot nematode (Meloidogyne species)||Can survive in the soil as egg masses. Prefers warm temperatures.||Carrots; potatoes; beetroot; sweetpotato; parsnip; tomatoes; eggplant; capsicum; celery; onions; peas; beans; spinach; herbs;cucumber; Brussels sprouts; radish||Root swellings or galls are clear on the roots and plants show stunting and yellowing. Water uptake is reduced so plants wilt.|
- Soil testing – This gives an indication of the risk of planting a particular field and the necessity for chemical treatment. As nematodes often have a patchy distribution, it may be possible to split the field into sections, collecting samples for testing from each section.
- Rotations and break crops – Rotations and break crops are best chosen with accurate soil counts of particular nematode species. Rotate susceptible crops with non-susceptible crops like cereals and grasses.
- Fallow – A period of more than six months can reduce populations of some nematodes, but may not reduce numbers below damage thresholds. It is important to maintain a bare fallow, as weeds can act as hosts and allow nematode numbers to increase. Plough out the crop as soon as harvesting is finished.
- Planting – Planting in late autumn or early spring can allow crops to become established when soil temperatures are cooler and less conducive to invasion and production of nematodes.
Restricted movement of potato material:
- Potato cyst nematodes
- Nematode control in carrots
- Best practice for vegetables
- Best practice for vegetables
- Root Knot Nematode on Potatoes
- Potato cyst nematode
- Stem and bulb nematode, an important pest of vegetables and other crops
- Root lesion nematode
- Green beans: insect pests, beneficials and diseases
- Cucurbit Ute Guide
- Insect pests of cucurbit vegetables
- Pests, Beneficials, Diseases and Disorders in Cucurbits
- Pests, Diseases, Disorders and Beneficials in Greenhouse Vegetables: Field Identification Guide
- Insect pest guide: a guide to identifying vegetable insect pests and their natural enemies in the dry tropics
- Diseases of Cucurbit Vegetables
- Pest and Disease Management (Vegetables WA)
- National IPM newsletter
- Integrated disease management in greenhouses
- Integrated pest management in greenhouses