During this time of year, Biobest advises cucumber and gherkin growers in Western Europe to install traps in their greenhouses. “In the beginning of a new cultivation period, growers should hang these above their plants,” says Pascal Briand, IPM and Pollination Specialist at Biobest. “This is the place where thrips establishes itself first.”
Many pest insects like whitefly, leafminers and aphids are attracted by the colour yellow. Thrips, one of the most common pests in cucumbers, don’t dislike yellow, but their true favourite is blue. Moreover, beneficials like parasitic wasps are not attracted by this colour.
The rule of thumb for blue Biobest’s Bug-Scan traps is 40 per hectare of protected crops. To monitor the population evolution properly a weekly or biweekly thrips ‘check and count’ will do.
When thrips have been detected, it is important to react promptly with curative control measures, for example the introduction of predatory mites like Amblyseius swirskii and/or Amblyseius cucumeris. “If in the past, thrips appear on a frequent basis, we advise to apply these mites as a preventive strategy” says Pascal. “Also in this case, frequent monitoring remains advisable.”