Yellow rust still a great challenge for wheat growers

The yellow rust has mutated yet again this year to overcome several wheat varieties that were previously resistant.

The yellow rust mutates every few years, and the Oakley variety has also fallen victim to a new strain.

While yield, quality and end-markets will continue to be the main drivers behind variety choice, disease resistance must be remembered because of its influence on a variety achieving its potential and the cost of doing so, said Rosemary Bayles, Principle Cereal Researcher from the National Institute of Agricultural Botany (NIAB).

Year 2009 has brought the disease into prominence because of the impact of recent race changes on several popular varieties and some up and coming ones, she said.

The season showed once again how the pathogen can evolve to overcome the genes on which varieties depend for resistance. Variety diversification helps growers choose which combinations to grow and eases management spreads the risk, said Bayles.

But few growers, except those in the highest risk areas, routinely make much use of diversification, though interest is likely to increase next season, she said.

If yellow rust appears in one variety on the farm, it's important to know which others on the farm are at risk from the same race and their relative susceptibility. That helps plan the most efficient and cost-effective disease control strategy, she said.

Seed treatment alone is not the solution, as it would be wise to spread the overall rust risk and reduce seed treatment cost with less susceptible varieties from other diversification groups, Bayles advised.

Peter Riley of Prime Agriculture in Norfolk also urges growers to take notice of yellow rust ratings, which would help them in fending off the disease to a certain extent.