Science into practice better risk assessment of onion stem nematode

Stem nematode is a very destructive pest of bulb onions that would, if left untreated, cause an estimated annual crop loss of around £1m. Unless growers are confident that the risk of infestation of fields is low, they are loathe to leave crops untreated, but supermarkets are requesting nematicide-free production.

The pest spends most of its life in the plant so numbers in soil are usually small. Soil sampling protocols are the only way to assess risk, therefore they need to give the maximum chance of detection. HDC project FV 327 aimed to develop optimum methods of soil sampling and analysis.

For mapping the in-field distribution of stem nematode the project took advantage of soil sampling equipment linked to differential GPS. Intensive soil sampling was concentrated on three fields known to pose low, medium and high risk to crops. Stem nematode distribution was mapped and a sampling method drawn up to give the best chance of detecting it. As not all soil extraction methods are equally effective at recovering stem nematode, four methods were compared in the laboratory.

More nematodes were recovered from the pneumatically-sampled than hand-sampled soil, irrespective of extraction method. Stem nematodes occurred in distinct patches in infected fields, so a systematic rather than random sampling pattern is needed for accurate population counts.

A sampling grid of 100 points covering 4ha is the best compromise between accuracy and the time required, replacing the method of sampling along a W pattern. Of the extraction methods tested, the Seinhorst two-flask technique extracted two or three times as many nematodes as others.

Horticultural Development Company

For details on all HDC activities, visit www.hdc.org.uk.


Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Sign up now
Already registered?
Sign in

Before commenting please read our rules for commenting on articles.

If you see a comment you find offensive, you can flag it as inappropriate. In the top right-hand corner of an individual comment, you will see 'flag as inappropriate'. Clicking this prompts us to review the comment. For further information see our rules for commenting on articles.

comments powered by Disqus

Read These Next

What is being done to develop biocontrols against orchard pests?

What is being done to develop biocontrols against orchard pests?

The SIVAL horticultural trade show in Angers, France, this week (16-18 January) heard about several initiatives to promote more environmentally sustainable orchard growing.

What does the 25-year plan mean for growers?

What does the 25-year plan mean for growers?

Published on 11 January, the Government's long-awaited 'A Green Future: Our 25 Year Plan to Improve the Environment' brings together a number of policy strands into a single framework that will impact many sectors, not least fresh produce, over the coming decades.

What will 'embracing change' mean for horticulture?

What will 'embracing change' mean for horticulture?

At the Oxford Farming Conference, whose theme was "embracing change", Defra secretary Michael Gove expanded on what a post-Brexit UK agriculture and land-use policy will look like and how it will impact farmers and growers.


Follow us on:
  • Facebook
  • LinkedIn
  • Twitter
  • Google +
Horticulture Jobs
More Horticulture Jobs

Pest & Disease Tracker bulletin 

The latest pest and disease alerts, how to treat them, plus EAMU updates, sent direct to your inbox.

Sign up here

Professor Geoffrey Dixon

GreenGene International chair Geoff Dixon on the business of fresh produce production
 

Read Professor Geoffrey Dixon