Population dynamics of Heterodera avenae Woll. in South Australia

Abstract

Population changes of the cereal cyst nematode (Heterodera avenae Woll.) under various rotational regimes in the field were examined. A density of 5 eggs/g soils caused a loss of about 10% in yield of wheat cv. Bayonet under the experimental conditions. Maximum multiplication rate at low initial densities was about l0x, but this rapidly decreased as initial density increased. Equilibrium levels ranged from 15 eggs/g soil up to 40 eggs/g under different conditions. The resistant wheat, Aus 10894, maintained an equilibrium level of about 1 egg/g soil-a level low enough to avoid damage in a following crop. Annual percentage hatch varied from 70-90% with an average of 85%. Presence or absence of plant species had little effect on per cent hatch. About 7.5% of the nematodes successfully penetrated and became established in the root systems of seedlings, invading both seminal and nodal roots, but only about 0.5% became established in the principal axes of the seminal roots. The implications of these data for various rotational practices are discussed.