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NL:"Big difference in thrips pressure compared to last year"

Based on degree days, it is possible to calculate when the first thrips pupae will hatch outside. Over the past two weeks, this has happened outside in the Dutch fields. However, thrips also appear to be more active indoors during the winter than first thought. When monitoring, HortiPro regularly sees them in the fields.

In greenhouses, thrips are often present all year round anyway. As a consequence growers increasingly keep a close eye on pest development with the help of sticky traps and HortiPro's pheromone PheroThrip 2.0.

"We encounter many different species of thrips under glass," shares Lennart Simonse on behalf of the pheromone supplier. The consultant counts the catch on sticky traps at growers' premises. After a dark spring in The Netherlands, thrips pressure in many greenhouses is lower than last year. "The difference with last year is big," he says. It is therefore important to monitor the population closely and, if necessary, control thrips in time.

Lennart checks a sticky trap between potted anthuriums. PheroThrip 2.0 allows growers to monitor thrips.

Intensive thrips monitoring
Knowledge of thrips development, indoors and outdoors, is increasing every year. For about four years now, HortiPro has been working on PheroThrip 2.0, (intensive) monitoring is central to this approach.

Potted anthurium grower Leon Breugem and cut hydrangea grower André Vollering (link to article in Dutch) were among the early adopters. The growers use the knowledge from the weekly monitoring to act in time. At the time, they noticed that thrips were much earlier present in the greenhouse than initially thought. And also in larger numbers.

This is what a caught thrips looks like, magnified for clarity

Timely intervention
Even though thrips development outside started relatively late, and the pest pressure in greenhouses is limited, Lennart knows of examples where intervention with a plant protection product was still needed this spring. "By intervening in time with a (green) pesticide, the thrips pressure can be brought down again. Then the biological control agents can further control the thrips."

With timely insight into thrips development, growers can intervene in time, ultimately allowing them to grow more organically. Several years later, that is still how it works. The number of authorized crop protection products is still decreasing in The Netherlands. Meanwhile, growers invest in insect netting, but not all mesh sizes keep out thrips. The little critters are not easy to catch, but they do appear to be eager to get hold of HortiPro's blue sticky traps with thrips pheromone, Lennart sees time and again.

HortiPro works with blue sticky traps

Catching more thrips
For monitoring purposes, HortiPro uses blue sticky traps containing the PheroThrip pheromone. Growers themselves sometimes also use regular yellow sticky traps. "According to our counts, we sometimes catch factor ten more with our blue sticky traps with pheromone compared to the yellow sticky traps. An additional advantage is that thrips stand out better against a blue sticky trap. That helps in counting and distinguishing the species." And thus helps growers gain insights on what to do to keep thrips pressure low.

For more information:
Lennart Simonse
[email protected]

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