The root knot nematode (Meloidogyne incognita) represents a threat in the cultivation of tomato in organic greenhouse horticulture. Together with growers, the Farming Systems Ecology group of Wageningen University and WUR Greenhouse Horticulture a trial was started to investigate diverse means of control.
For the trial, 5 L pots were used and filled with soil that originated from a grower. The investigation included diverse types of compost, additives such as silicon and diverse antagonists of the root knot nematode. The means of control were tested separately and combined to study a synergistic action. Especially a woody type of compost and champost with silicon were effective and reduced the number of root knots on the root system of tomato cv. Capricia. In addition, woody compost reduced the number of offspring (J2) from the infested roots. An addition of the fungus Trichoderma sp. was counter effective. A combination of champost and silicon was effective as well. The combination showed even a synergistic effect, i.e., it was more effective in reducing the number of root knots when compared to champost and silicon separately. Champost has to be used with care since it may result in a damage of the roots.