2 February 1996

Low-tech spray test picks up blackgrass resistance

EXTRA help in checking whether blackgrass is herbicide resistant is close, it emerged at the recent Association of Independent Crop Consultants annual conference.

A simple "low-tech" spray test on tray-grown plants was "encouraging" in being able to pick up very low levels (0.1%) of target-site resistance, said Dr Stephen Moss of IACR Rothamsted.

But a quicker method, based on germinating seeds in Petri dishes, had attracted MAFF cash – all it needed now was a researcher to refine it over the next two months.

Assessing enhanced metabolism or "shades of grey" type resistance could become easier and quicker with a new fluorescence meter, he explained. Currently the standard method involves test germination and over-sprays.

The new equipment, the £3,500 Hansatech Plant Efficiency Analyser, can be used to measure the degree of photosynthesis still taking place after leaves have been allowed to take up herbicide.

"It certainly needs more development before it could be used routinely," said Dr Moss. "But in the near future it has quite a lot of potential." The need to work with pristine leaves though suggests it is unlikely to be used in the field.

Hope is at hand for growers wanting a quick answer to blackgrass resistance queries, says Rothamsted researcher Steve Moss.