Plant parasites are an extremely challenging and troublesome pest to gardeners. They are so small that they are almost invisible without a microscope, which makes them difficult to detect. The symptoms are similar to other common conditions, such as over watering, under watering and poor soil conditions. To diagnose the parasites, you need to take a soil sample to a laboratory. The most common of these parasites are nematodes. Avoid getting nematodes by buying plants from reputable distributors, examining the soil with a magnifying glass before planting, and keeping the soil in optimal condition.
Increase the amount or organic matter in the soil by working it into the top soil and using it as a mulch. Green manure is particularly effective at combating nematodes. Organic matter encourages the growth or other microorganisms that the nematodes do not like. This makes the environment less hospitable.
Plant suppressive plants in the effected area. These plants release chemicals that are toxic to the nematodes as they grow. They will not completely eradicate the nematodes but will reduce their population enough that your plants can go. Marigolds are easily found suppressive plants. They come in many varieties so will grow in almost any climate. Plant them in any empty space in the affected area for the best result.
Remove all the plants from the area and rework the soil using chemical pesticides, called nematicides. These chemicals are toxic and should be used as a last result. They come in many forms including liquids and granules, but they all need to be worked into the soil before the area is planted. Wear protective gloves when working with these chemicals, and follow the manufacturer's instructions. In the case of granules, spread them on top of the soil, and then work them in when you till the soil.
- University of Maryland: Introduction to Plant-Parasitic Nematode Biology and Management
- Recognizing and Controlling Nematode Damage On Some Crops Grown in Jamaica; Dave George Hutton
- Alabama Cooperative Extension System: Nematode Suppressive Crops