Biocontrol of S. sclerotiorum

... by field application of CONTANS WG® (Coniothyrium minitans) in Germany

CONTANS WG®, a biofungicide manufactured by the Prophyta company (Malchow, Germany), contains 10^9 g-1 living conidia of Coniothyrium minitans. CONTANS is a registered fungicide in Germany for biocontrol of Sclerotinia sclerotiorum since 1998. C. minitans is a host-specific mycoparasite of Sclerotinia species and colonizes and degrades the sclerotia of its host (Fig. 1). Its main application is in oilseed rape for control of white mould. Field experiments have been conducted in order to evaluate the biocontrol efficacy of CONTANS WG® under practice conditions and to optimise the application technique with regard to timing within crop rotation and soil management. CONTANS WG® was applied either on the stubble or the soil during three consecutive years at field sites in Northern Germany (Fig. 2).

The parasitism of bait sclerotia buried in the soil in autumn was dependent on soil depth, application method and application rate. Parasitism rates of bait sclerotia during winter months (September until May) reached 65% reducing the sclerotial survival rate to 8%.

In mini-plots, the antagonist initially applied at a rate of 3,3 x 105 cfu/g to the soil, was still detectable after 60 months of field exposure. The established antagonist population consistently reduced the survival of sclerotia to levels between 6.6 and 0.2% from 6 to 60 months duration of the experiment. Application of the biofungicide on the oilseed rape stubble vs. treating the stubble of the previous crop (barley) or application on the soil prior to sowing of oilseed rape increased the reduction rates of apothecia from 10-30% to 50-80% (Fig. 3). The data clearly demonstrate a potential of efficient and sustainable biocontrol of Sclerotinia diseases by CONTANS®. This is the first example of a successful biocontrol strategy for a fungal disease in large-scale arable crops.

Mini-plot crop rotation experiment
Fig. 3. Mini-plot crop rotation experiment: in 2001 an oilseed rape-wheat-barley rotation was started where 400 sclerotia per plot (0.64 m2) were spread on the soil. CONTANS was applied on stubbles of a previous barley crop (StubBarley), on soil prior to sowing of oilseed rape (Presowing) or on the plant debris of OSR ing two years was 50-80% in StubRape while effects of application presowing or on barley stubble were insufficient

Selected publications:

  • Daoud I, Hedke K, von Tiedemann A (2006). Importance of application mode for the efficacy of CONTANS (Coniothyrium minitans) in biocontrol of Sclerotinia sclerotiorum. IOBC Bulletin 2006, Vol. 7. Proccedings IOBC-Workshop Working Group Integrated Control in Oilseed Crops, 353.
  • Tiedemann v., A, K. Hedke, R. Mögling (2001). Abbauverhalten von Sklerotien der Weißstängeligkeit bei Einsatz von Contans. Raps, 1, 21-23.