Population Studies on the Potato Root Eelworm (Heterodera rostochiensisWoll.)

When potatoes are planted in eelworm infested land, the root diffusate produced results in 70—80 per cent, of the larvae emerging from the cysts in the first 4—5 weeks of growth and this effect is shown up to a distance of 6 in. from the root centre. 2. Moderate or heavy soil infestations of potato root eelworm result in a considerable root invasion prior to potatoes breaking through; several thousand cysts can result from this early attack and can cause severe dislocation of the young root.