In- vitro effects of extracts of brassicaceous green manures on the movement and host location of Globodera rostochiensis second-stage juveniles

Potato cyst nematodes,Globodera rostochiensis and G.pallida, cause severe yield reductionin potato, andare the most important quarantine nematode pest for this cropin Europe. Sincemany decades, farmers arefacingdifficulties for the management of these species as their biological characteristics allow them to survive in the soil for several years. In addition, the use of chemical nematicides has been restricted in several countries, forcing farmers to search for environmentally friendly methods to control nematodes.Soil amendments with green manures received much attention as a management practice, especially with brassicaceousplants because isothiocyanatecompounds are releasedat the breakdown of their tissues. This study evaluated the effectof root diffusates and extractsobtained frombrassicaceousplants on the movement and host location of G. rostochiensissecond-stage juveniles (J2). Root diffusates and extracts ofplant tissues were obtained from yellow mustard (Sinapisalba), rapeseed (Brassica napus)and fodder radish (Raphanussativus). The effect of these solutions on the movement of J2 was tested by direct exposure and in sand columns. The effect on the sensory perception was evaluated in water-agar and pluronic-gel plates with a tomato seedling as the attracting host. The movement of J2 was significantly reduced by direct exposure to extracts made from roots and from above-ground tissues,and so was the migration through sand columns.Juveniles pre-exposed to the diffusates or extracts of green manures could not readily detect the presence of a host in the agar or pluronic-gel plates, moving away from it during the first 8 hours of the experiment. These results indicate that breakdown of brassicaceous plant tissues have disruptive effects on the mobility and sensory perception ofG. rostochiensis juveniles, making these plants interesting for application in environmentally friendly management options.