Cereal Cyst Nematode, Soil Heating and Fungal Parasitism1

Experiments on winter heating of cereal cyst nematode-infested soil have been carried out during 4 years on light loam in eight concrete pipes (l-m diam.) dug into the soil. The soil in four of the pipes was heated to a temperature of 5oC during the winter periods. Temperature was measured at a depth of 5 cm. The heating was carried out by means of buried electrical cables. Soil temperature in the remaining pipes followed the natural fluctuation. The host plant was Sun II oats. Statistical analysis of the results for all the years together showed that the propagation of nematode populations was significantly lower in heated than in non-heated plots. Investigation of soil samples in spring and autumn 1980 for eggs and larvae, as well as fungal parasitism of these, showed that numbers of eggs and larvae were significantly lower in heated than in non-heated plots and the percentage of parasitized eggs and larvae was significantly higher in heated than in non-heated plots. Verticillium chlamydosporium seems to be a main parasitic fungus.