Nematode research

Nematodes are microscopic, worm-like, soil dwelling animals. There are many types of nematodes, a total of 28,000 have been described, of which 16.000 are parasitic. In addition, there are other ones, in particular saprophytic nematodes, that contribute to a healthier soil life. Of the known parasitic nematodes, 3.000 feed on plants, of which 200 species cause considerable damage in cultivated crops. The damage they cause can be visible (e.g. malformed crops, leaf discolouration) and invisible (e.g. yield reduction) and can also lead to secondary infections.

Once damage from nematodes is visible, it is too late to intervene. The result can be crop rejection, loss of revenue and / or quality loss. It is therefore important to be alert and to systematically sample plots for good nematode management.

An integrated approach to nematode control is essential, with the disappearance of chemical soil disinfectants. Growing a resistant cover crop is not only a very effective way to control nematode populations, but they can also benefit the soil by enhancing its fertility, improving its structure and increasing its biodiversity.

Host plant status and damage susceptibility

The host plant status is the extent to which nematodes can multiply on a particular cash or cover crop. Nematodes that produce several generations a year can increase from low densities to maximum densities in one season. How high that maximum density is depends on the crop. The absolute numbers vary per nematode species. The host plant status is therefore divided into the following propagation classes:

  • Active control (resistant)
  • Non-host (= natural decrease)
  • Bad host (= low increase)
  • Moderate host (= moderate increase)
  • Good host (= strong increase)

Damage susceptibility indicates the extent to which the crop suffers damage from the relevant nematode species. Damage is caused by the combination of damage susceptibility of the crop and the number of nematodes at the start of the cultivation (contamination level). The damage can not only relate to a loss in yield, but can also relate to quality or prohibit cultivation because the nematode is a quarantine organism. Classes indicate damage susceptibility:

  • No damage
  • Little damage (5-15% damage)
  • Moderate level of damage (15-33% damage)
  • Strong level of damage (>33% damage)

Source: www.aaltjeschema.nl