Biology and Epidemiology

- Survival  and source of inoculum

The nematode, Ditylenchus dipsaci, can survive for several years in the soil as fourth instar larvae. It can also remain alive for a decade in dried plant debris (in the larval stage). There are a number of cultivated crops and weeds suitable for the survival and the multiplication of this nematode .


- Penetration into the plant and invasion

In heavy, wet soils, Ditylenchus dipsaci  attacks the parenchymatous tissues of the plant through which it enters, colonises and progressively alters the tissues. Often secondary micro-organisms are established  in the damaged tissues. Each female gives birth to several hundred eggs which go through four larval stages.


- Dissemination

The presence of a large amount of water in the soil and water dripping favour the migration of the nematode to the surrounding healthy plants (the problem appears in foci). Agricultural tools used for cultivation can contribute to the nematode dissemination to other fields. Seed transmissions are reported in other plant species such as white clover, faba beans and broad beans.


- Favourable conditions for the nematode development

As mentioned earlier, the disease occurs severely during periods of cold and wet weather on heavy soils. This is likely the reason why it is more severe in tobacco in northern Europe. Young plants are more susceptible than older plants.