Root knot nematode
Meloidogyne spp.

They exist in soil in areas with hot climates or short winters.  Infection of young plants may be lethal, while infection of mature plants causes decreased yield.

Symptoms: You may notice that even with moist soil your plants still wilt, turn yellow, and may eventually even die. If your garden is infected with nematodes, you may not notice their presence during the cool seasons because their populations peak during summer, and by that stage, when you notice plants wilting, it's too late to do anything about that particular crop.

Identification: If you think your plants are infected, dig up a plant, rinse the soil off the roots and inspect them. Nematodes present as tumour-like growths on the roots, which may be tiny or take over the entire root system. Remember that beans and peas fix their own nitrogen in the soil, which is stored in small growths similar to nematode tumours, so check other plants in your garden first before diagnosing from legumes.

Plants affected: Many plant species are affected by this particular nematode, but it mostly causes damage to the following plants:

* The solanaceae family, which includes potatoes, eggplant, capsicum, chilli and tomatoes.
* Cucumbers, melons and pumpkins.
* Strawberries, peaches, bananas, grapes, passionfruit, pineapples, pawpaw.