Reproductive capacity of Heterodera schachtii on Thlaspi arvense, Capsella bursa-pastoris and varying populations of Chenopodium album

Abstract

Weed management in field crops is based on threshold levels. Direct yield reductions by weeds can be quantified, but indirect effects by serving as alternate hosts of plant–parasitic nematodes are more difficult to assess. In Germany, intensive cultivation of sugar beet in 3-year rotations with cereals provides long fallow periods between harvest and planting of the following crop. Weeds developing during this period could serve as hosts of Heterodera schachtii, the sugar beet cyst nematode. In previous studies, only limited nematode population density effects were detected during the stubble period. Physiology and population characteristics of the potential host plants may impact reproduction potential of H. schachtii. In a microplot experiment, reproduction of H. schachtii was measured under Capsella bursa-pastoris, Chenopodium album and Thlaspi arvense, and compared to that under susceptible Beta vulgaris during the vegetation period from spring to late summer. There was no difference in population density of H. schachtii on the weed species, but all were much lower than under B. vulgaris. In a greenhouse study, the reproduction of H. schachtii on nine populations of C. album from different regions of Germany was compared to that on each of a susceptible and resistant cultivar of B. vulgaris and Raphanus sativus. All C. album populations supported lower reproduction (<2 %) than the susceptible sugar beet and oilseed radish. Lower nematode population density and negligible reproductive potential on a diverse selection of C. album support the hypothesis that the risk of H. schachtii population buildup under these weeds is limited.