Dual Resistant Pea Varieties

Pea varieties with dual resistance to downy and powdery mildew should become available because of an early screening process developed by the Pulse Pathology team at the South Australian Research and Development Institute (SARDI).

SARDI researchers, funded by GRDC, have developed early generation screening techniques, which promise the growth of downy and powdery mildew on susceptible lines.

The technique involves inoculating a number of seedlings of each breeding line with downy mildew. These are grown in a controlled environment room with temperature and humidity conditions set up to ensure disease expression on susceptible varieties.

After 3-4 weeks incubation, each seedling is rated for the degree of susceptibility to downy mildew. Plants with less than 10% coverage of the underside of the leaf and the stem are rated as resistant. Those with more than 70% coverage are rated as susceptible.

After the downy mildew screening is completed, the same seedlings are then transferred to the greenhouse and inoculated with powdery mildew. Again, plants are rated for the level of disease coverage, but this time the researchers look for the powdery mildew that forms on the upper surface of the leaves.

Researchers were able to identify lines with complete resistance to powdery mildew and could identify those with resistance to both the mildews.