Rapid detection of herbicide resistance

The use of herbicides to kill weeds in conventional farming is necessary to maintain yields and prevent a persistent seed bank of pathogenic weeds storing problems for the future. But the widespread use of any chemical control can lead to resistant weeds emerging: for example, resistant black-grass has been found on over 2000 farms across 32 English counties.

Early detection is vital, so to help farmers detect resistance on their fields, and hence improve prevention and management strategies, the ‘Rothamsted Rapid Resistance Test’ was devised by Dr Stephen Moss (pictured below) at Rothamsted Research, an institute of BBSRC, in 1999.

The Rothamsted Rapid Resistance Test on three black-grass populations. Greater growth in the two lower dishes indicates a high degree of resistance to the herbicide pendimethalin compared to the upper dish. Image: Rothamsted Research

The resistance test requires no sophisticated equipment and involves germinating weed seeds in dilute herbicide solutions in an incubator. Seedling growth after 2 weeks gives an indication of the degree of resistance.

The practical interpretation of results is greatly enhanced by the inclusion of standard reference populations which have been fully characterised, not only at the whole plant level, but also at the biochemical and molecular level. Simple visual estimates, which take 10 seconds per Petri dish, are as accurate as actually measuring shoot lengths, which takes 100 times longer

Dr Stephen Moss

The simple approach, speed and cheapness are major advantages which have led to the ‘Rothamsted Rapid Resistance Test’ being used as a ‘standard’ methodology in the UK and also in many other countries. Test results have formed the empirical basis of new strategies for preventing, characterising and managing herbicide resistance.

The test continues to be refined as new types of resistance have evolved and new herbicides have become available.

Dr Moss won the 2009 Technology Award of the Royal Agricultural Society of England (RASE) in recognition of the practical impact of his research.