Influence of green manure and other organic amendments on the population dynamics of the sugar beet cyst nematode Heterodera schachtii (Schmidt)
1989
Nicolay, R. (Bonn Univ. (Germany, F.R.). Inst. fuer Pflanzenkrankheiten) | Sikora, R.A.
The number of newly produced eggs and juveniles of Heterodera schachtii on rape was reduced 55, 94 and 90 per cent compared to the control following incorporation of rape, mustard or oil radish as green manures into field soil. The factor responsible for the reduction was localized in the shoots. Studies conducted at a constant temperature of 21 degrees C showed that the suppressive activity of rape lasted approximately three months. Suppression of nematode multiplication was also detected when the soil and green manures were heat sterilized, with the greatest effect observed with oil radish. Increasing shoot weights were positively correlated with the number of newly formed eggs and juveniles, however not consistently due to amendments or to a specific green manure crop. Reduction in the number of newly formed cysts was the main factor responsible for decreased nematode multiplication. The decrease was not caused by suppressed root penetration but most probably by either retardation, inhibition or alteration of juvenile development in the root after green manuring. Incorporation of 1 or 10 per cent compost caused decreased nematode multiplication 2 - 4 months after addition to field soil. Water extracts of the crucifers caused inhibition of juvenile motility which was reversible in water
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