Nematodes are a species of roundworms; they do not have segments and they may be flat and slimy. Many nematodes are actually beneficial: according to the University of Florida's Institute of Food and Agricultural Sciences, many species of nematodes feed on microscopic organisms (such as bacteria and fungi) that could harm plant-life if left unchecked. Plant-parasitic nematodes, however, are harmful to plants. If you suspect your plants are infected with plant-parasitic nematodes, you must kill them.
Change the dirt in your houseplants and use an organic mulch. Organic mulches contain organisms such as certain fungi and predatory nematodes which will attack and help control plant-parasitic nematodes.
Remove visibly-affected leaves and plant matter from the plant, but be wary not to take too much of the plant that you severely damage it.
Place your plant under a sunlamp. Nematodes are susceptible to heat; if the heat is hot enough, the nematodes will die. You must be careful, however, no to use too much heat so as to kill the plant itself.
Spray sugar-water onto the plant. According to gardenguides.com, sugar is a natural insecticide and can be used to kill nematodes. Pour a half of a cup of sugar into a spray bottle of water and spray it on the soil and lightly on your plant.