8 March 2002

Bean pests worrying

STEM nematodes, increasingly being found in field bean seed samples, cast a shadow over the future of the crop in the UK, warns the PGRO.

Infection by the soil- and seed-borne pests which devastate bean crops and slash yield by 70% is definitely worsening, says researcher Anthony Biddle. "It is getting to be a very severe problem."

Recently up to 40% of seed samples tested, most of them farm-saved, have contained the nematodes.

"That is a lot worse than four or five years ago. One problem is that it is a very easy crop to farm-save and a very high proportion of that seed never sees a laboratory [for testing]."

Once the nematodes, of which there are at least two races, are in the soil it is best not to grow beans again for 10 years, he advises. "There really isnt a threshold. We say if you have infected seed do not sow it."

Crops grown from infected seed are stunted, with brown thickened and distorted stems, shrivelled pods and "coal black" beans, notes Dr Biddle. &#42