Water potential affects Coniothyrium minitans growth, germination and parasitism of Sclerotinia sclerotiorum sclerotia

► Osmotic and matric potential effect on growth of eight C. minitans isolates assessed. ► C. minitans parasitism S. sclerotiorum sclerotia at soil water potentials assessed. ► Growth and germination response of isolates varied at different water potentials. ► Low soil water potential inhibits C. minitans infection sclerotia. ► Sclerotial viability reduced over wider water potential range by LU545 than LU112.