Weeds with resistance to herbicides are much more common than expected. This according to a newly published study which found resistant weeds on 48 per cent of Canterbury wheat and barley farms. The study led by Dr Chris Buddenhagen of AgResearch expected five to 10 per cent of these farms would contain resistant weeds but found it was a much more serious issue. Resistance on a farm was like a lottery with some farms in the study having severe problems, while others had no weeds present at all. Dr Buddenhagen and his colleagues collected seed samples from common weeds from 87 Canterbury wheat and barley farms just before harvest. They raised more than 40,000 seedlings in glasshouse conditions resulting in some form of resistance. The 87 farms surveyed represented about 20 per cent of wheat and barley farms in Canterbury. Mind you t the 48 per cent figure was low compared with some areas of Australia, where resistance is closer to 80 per cent.