Effect of waterlogging on the severity of disease caused by Mycosphaerella pinodes in peas (Pisum sativum L)

The effect of waterlogging on the severity of disease caused by Mycosphaerella pinodes infection in field pea was measured in 2 experiments in the glasshouse. Disease significantly reduced root and shoot growth in both experiments. In a comparison of 2 cultivars with different sensitivities to waterlogging, the severity of disease was lower in the cultivar which was less sensitive to short-term waterlogging. Flooding the roots of plants after infection increased the visual symptoms of disease, but if plants were inoculated with the pathogen after flooding commenced, disease severity was reduced by waterlogging. Inoculation before waterlogging significantly reduced plant dry matter, but there was no reduction in plant growth by disease when inoculation occurred after waterlogging commenced. The results suggest that waterlogging of peas already infected with Mycosphaerella pinodes may result in more severe infection and greater reductions in plant growth, and cultivars more sensitive to waterlogging damage may also suffer greater losses from disease.