Secondary infection makes diagnostics difficult.
Crops grown on soil often suffer damages due to nematodes. Not all nematodes are plant parasitic. On the contrary, far the most of the nematodes present in soil are saprophytic. They live from organic debris, bacteria and fungi. In just one gram of soil thousands of nematodes can be present. Only the plant parasitic nematodes harm the crops. In contrast with saprophytic nematodes the plant pathogenic nematodes have a stylet. With this stylet they pinch into the cell wall and excrete enzymes which damage or destroy the cell. In reaction the plant shows symptoms like lesions or necroses, root knobs, malformation of leaves or roots, twisted stem or leaves, interruption in growth, etc. Root nematodes can cause severe damage. They hinder not only the uptake of water and nutrients but also the transportation of these. In case of serious damage the plant can even die.
Host plants and symptoms variable
The amount of hosts differs per kind of nematode. Some nematodes have a great variety of host plants, e.g. the root lesion nematode Pratylenchus. Crops which are not susceptible for this nematode are rather uncommon. Other nematodes have much less host plants, like Ditylenchus. Especially Ditylenchus destructor can cause severe economical damage to for example potato and several kind of flower bulbs. Once a plot of land is infected by Ditylenchus it is recommended not to grow susceptible crops for years! Other real common nematodes are the root knob nematode Meloidogyne and the leaf nematode Aphelenchoidus. Aphelenchoidus can cause malformation of above ground parts of the plant.
The amount of damage caused by nematodes is in the first place due to the number of nematodes that attacks the plant. But besides that, the wounds caused by these nematodes give other pathogens, like fungi and bacteria, also a simple entrance to the plant. There are also some nematodes, like Xiphinema, who are able to transfer plant pathogenic viruses. Roots damaged by nematodes are more susceptible for drought. Further, damaged roots have less uptake capacity of water and nutrients and that can result in deficiency problems in the crop. All these secondary symptoms make it often difficult to diagnose the original infection correctly.
Fast recognition prevents serious damage
If you want to know more about nematodes or to cheek if you have a nematodes in your soil or plants please contact us.