Conditions for collecting the potato root-diffusate and the influence on the hatching of potato cyst nematode

Abstract

Several kinds of experiments were carried out to study the influence of the conditions, under which the potato root-diffusate was collected, on the hatching of potato cyst nematode, Heterodera rostoehiensis Woll.
The root-diffusate was collected by saturating the soil with 2l of tap water in 1/5, 000a pot in a greenhouse at about 25°C, where 2 potato plants were grown and by draining the solution from the pot after certain period of time. This solution was filtered and stored at 5°C until use.
The root-diffusate collected within 66 days after transplanting the potato seedlings of about 5 cm in height gave the hatching rates higher than 60%, especially that collected in a period from 20 to 40 days after transplanting gave higher hatching rates over than 90%. So, this period is considered to be an optimum time to collect the root-diffusate.
In the terms of stimulating effect on the nematode hatching, there was no appreciable difference in the duration of time from the initiation of saturating the soil to draining the solution from the pots. Namely, the solutions collected from just after the initiation of saturating the soil till 48 hrs after it gave almost the same rates of hatching, higher than 70%.
A solution was collected at any time from the soil from which the roots of potato plants were removed at the time of flowering. The hatching rate was higher than 60 % in the solution collected one month after the removal of the roots and a weak but obvious effect on the hatching was found to remain till 100 days after it.
The root-diffusates collected from five potato varieties differing in the maturation period were examined. Those solutions collected before 49 days after transplanting the seedlings showed a high effect on the hatching in the cases of all of the varieties and no difference was noted among the varieties so far.