Numbers of mononchid nematodes in soils sown to cereals and grasses

The distribution of mononchid nematodes Mylonchulus sigmaturus, Mylonchulus brachyuris, Clarkus papillatus, Prionchulus punctatus and Anatonchus tridentatus found in grassland and arable soils in England were studied. Mononchid nematode populations in excess of 5% of the total soil nematode population and in biomass more than 2% of the total soil nematode population were rare. No relationship was found between numbers of mononchids and those of other soil nematodes. In soils sown to spring barley there was no difference in the total numbers of female M. sigmaturus, C. papillatus or A. tridentatus found throughout the year. Juveniles of C. papillatus were most common while those of M. sigmaturus were least common. In grass leys and arable soil P. punctatus numbers were extremely low. Neither phorate nor oxamyl applied at 1.12 kg a.i./ha in March affected mononchid numbers. Although oxamyl at 11.2 kg a.i./ha did not affect the adult female numbers, the numbers of juvenile mononchids were reduced by 38% and 50% in June and November respectively.