Invasion and development of the cereal cyst-nematode Heterodera avenae in roots of barley infected by the take-all fungus Gaeumannomyces graminis

Observations on the invasion and development of Heterodera avenae in relation to take-all infection of barley roots were made in three pot experiments. Post-cropping H. avenae populations were lower on fungus-infected plants, as a result of the production of fewer, smaller and less fecund cysts. The reduction in cyst numbers was associated with reduced larval invasion of take-all infected roots and with the effects of the unfavourable environment of these roots on female development, possibly through its effects on sex determination and survival of the larvae.