14 November 2001
Biodiversity loss: ‘Herbicides not worst culprit’

By Andrew Swallow

HERBICIDES are not the main reason for biodiversity loss in the agricultural landscape.

The most beneficial weeds for seed-eating birds are not the most competitive with the crop, it emerged at this weeks British Crop Protection Conference in Brighton.

Reduced grazing, fertiliser use, drainage and scrub encroachment were all rated as more important causes of biodiversity loss than herbicide use in a poll of scientists, said Scottish Agricultural Colleges Neil Roberts.

The good news for growers aiming to increase biodiversity in their crops is that polygonum weeds like knotgrass and bindweed, plus fat-hen, are much better for birds than grassweeds like blackgrass and wild oats, explained RSPB head of research Jeremy Wilson.

“The problem of leaving weeds for birds is not as difficult as you might at first think,” he comments.

Meanwhile, SACs Neil Roberts stressed that farmers should be paid to keep weeds, or educated so attitudes on the value of weeds in crops change.

That would help resolve the conflict of interests between policy makers and growers.

The problem is biodiversity is highly valued by policy makers but growers want risk reduction and clean fields.

“One of the main reasons farmers control weeds is for pride.

“Why look at a grubby field when you can look at a clean field for much the same amount of effort.”