17 July 1998

Keeping tabs on crown rust

METHODS of monitoring crown rust susceptibility in variety trials have changed to help provide accurate assessment of the disease which was common on farms with excess grass last autumn.

Jim McVittie explains that crown rust is the most common disease of perennial ryegrass, typically seen in the autumn on longer swards. But cutting variety test plots every five weeks to assess yield has meant little disease has developed, making it difficult to assess differences in susceptibility.

Trial sites will now miss a cut at the begining of September to allow more disease to develop, providing more accurate asessment of susceptibility, he says.