Abstract

Clubroot (Plasmodiophora brassicae) is a serious soil-borne disease in brassica crops world-wide. We report on a time series of soil samples from Swedish long-term fertility trials started in 1957, 1963 and 1966, which were analyzed for the amount ofP. brassicaeDNA. The crop rotations included a brassica crop every 4 or 6years. All experimental sites with a 4-year rotation of oilseed rape, except one with calcium carbonate in the soil profile, showed high (>1000fg DNA g−1soil) levels ofP. brassicaeDNA after 9, 11 and 12 rotations. In contrast, detectable levels (>5fg DNA g−1soil) ofP. brassicaewere found only at one of five sites with a 6-year rotation of spring oilseed rape. In years with high levels ofP. brassicaeDNA, low yield was reported and a subsequent decline inP. brassicaeDNA in soil was observed. Different NPK (nitrogen/phosphorus/potassium) fertiliser regimes resulted in similarP. brassicaeDNA levels. The robustness and reliability of the method applied was verified by analyses of soil from individual plots compared with a mixture of plots and by repeated analyses of selected samples, which showed thatP. brassicaeDNA remained stable during dry storage.

Keywords

Long-termfertility; field trials; Clubroot; Soil samples; Plasmodiophora brassicae; Quantitative PCR; qPCR

Published in

European Journal of Plant Pathology
2016, volume: 145, number: 3, pages: 573-581
Publisher: Springer Verlag (Germany)

Authors' information