Potential for biocontrol of sclerotinia rot of carrot with foliar sprays of Contans® WG (Coniothyrium minitans)

Abstract

A glasshouse and field trial were conducted to evaluate foliar sprays of Contans® WG (Coniothyrium minitans) conidial suspensions for control of sclerotinia rot of carrot and infection of Sclerotinia sclerotiorum sclerotia by C. minitans. In the glasshouse trial, foliar sprays (1×10⁴–10⁸ conidia mL⁻¹) decreased the viability of sclerotia recovered from diseased plants and increased infection by C. minitans. In the field trial, three successive foliar sprays applied at 14-day intervals failed to reduce foliage disease severity, but significantly reduced viability of sclerotia recovered from diseased plants/crop debris and increased infection by C. minitans. No significant differences in sclerotial viability or infection were observed between two conidial concentrations (2.4 and 4.8×10⁶ conidia mL⁻¹). Foliar sprays of Contans® WG have potential for reducing viability of sclerotia produced on diseased foliage.

Keywords:

• Contans® WG
• Coniothyrium minitans
• Sclerotinia sclerotiorum
• sclerotia
• carrot

Acknowledgements

We thank Robert Redpath and Brian Pool for technical assistance and John Bilsland, Kettle Produce Ltd., Cupar, Scotland for providing field trial facilities, and P. Lüth, Prophyta GMBh, Malchow/Poel Germany for supplying Contans® WG. Financial support for this work from growers through the Horticultural Development Council (HDC) and the Scottish Government is gratefully acknowledged.