23 October 1998

Rapid test set for launch in new year

RESULTS from user evaluations of the new Rothamsted Rapid Resistance Test confirm its accuracy and ease of operation.

However, the time and precision required and the need for results to be interpreted carefully mean it is likely to be a tool for agronomists and advisers rather than farmers.

Resistance to herbicides in blackgrass, wild oats and Italian ryegrass is detected by germinating seeds in petri dishes containing various concentrations of herbicide. The number of seeds with shoots over 1cm long after two weeks indicates the level of resistance.

Reference seeds of known resistance are also grown and three products used to help identify which mechanism is involved and how severe it is.

"Although the test requires a seed sample, it is much faster than the standard glasshouse pot test, giving a result by mid to late-September from seed collected in July," says IACR Rothamsteds Stephen Moss. That means results can influence autumn herbicide strategies.

But most farmers are too busy when seed needs collecting in July to conduct their own tests, notes Dr Moss. Participants in this years evaluation spent two hours preparing each sample.

The test also quantifies the level of resistance, so advice can be tailored accordingly, which makes the interpretation of results important. Even consultants piloting the test found that challenging.

Careful seed collection, cleaning and storage at 30íC for at least two weeks to break dormancy are also vital to ensure good results, suiting the test to consultant rather than farmer use, suggests Dr Moss.

The cost of the test, which is due to be available next year, is likely to be £50-100 per sample.