Thrips treatment trials make progress

Biological and conventional controls are being explored to counter growing infestation problems.

Measures to counter the growing problem of infestation of soft fruit by western flower thrips (WFT) was the subject of two presentations at the recent Soft Fruit Day.

Originally from North America, WFT (Frankliniella occidentalis) has been detected on many food and ornamental crops and has been found to overwinter in strawberry fields, the audience at the East Malling Research Association/Horticultural Development Company (HDC) sessions heard.

"It causes bronzing on strawberries that makes the fruit unmarketable," said ADAS senior entomologist Jude Bennison. She is leading a five-year HDC and HortLINK-supported project to assess a range of biological and conventional controls with the aim of prescribing a full integrated pest management programme.

The mite Amblyseius cucumeris "can be unreliable" as a predator, while WFT is also showing signs of resistance to conventional pesticides, she added.

The flower bug Orius laevigatus also predates on WFT, Bennison explained. "But they are expensive and slow to establish, particularly when there are few flowers because they feed on pollen too. They are also sensitive to chemicals."

For this reason, the trial looked at incubating Orius in Alyssum plants, alongside Amblyseius, in tests that took place at Sunclose Farm in Cambridgeshire.

The combination of the two predators gave good control of thrips, she said. However, the effect of providing Alyssum banker plants had no effect on numbers of either WFT or Orius on strawberry plants.

Another approach to WFT control put forward by Keele University senior lecturer Dr William Kirk was to mimic signal chemicals (semiochemicals) emitted by the males.

His own work had revealed the chemical structure of WFT's aggregation pheromone, a precursor to mating, and this has since been commercialised by Syngenta Bioline.

Meanwhile, Koppert has developed Lurem-TR, which replicates a kairomone or attract chemical from the plant itself.

A HortLINK-supported project is now seeking to develop a pest-specific "sticky" monitoring trap using either or both of these, and to establish damage thresholds, he said. The colour of sticky trap has a bearing on their attractiveness to WFT, he added.

"If you get the right shade of blue, you will trap a lot more than on yellow," he pointed out. "They need a combination of colour and pheromone."

Research direction

Horticultural Development Company communications manager Scott Raffle told soft fruit growers at the Soft Fruit Day: "There's a lot more on this to come. Western flower thrip is such a problem for the industry."

He added: "You can influence what research we do. It's the job of our technical manager Andrew Tinsley to shape the projects you want to fund."


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