Rose thrips has a wide host range, including ornamentals, fruit, legumes and cucumbers. It commonly occurs in both outdoor and tunnelled strawberry crops in England and Scotland. However, until recently, this pest was not considered to require control in strawberry crops.
ADAS identified fruit bronzing where large numbers of rose thrips were present in crops, so AHDB commissioned a study to determine the threat and to identify the best control options for growers.
Where fruit damage has been attributed to rose thrips, growers have used integrated pest management programmes based on the predatory mite Neoseiulus cucumeris, which would offer good control of western flower thrips (WFT).
However, at these sites, rose thrips have not been controlled and the application of plant-protection products to prevent further fruit damage was needed. Tracer (spinosad) appears to offer effective control. But there is concern that, like WFT, rose thrips could develop resistance to Tracer and other insecticide products.
Rose thrips adult females are darker than those of WFT so can be distinguished in the field. However, males of both rose thrips and WFT are smaller than the females and are yellow, so they can easily be confused.
- Check a minimum of 20 flowers per crop every week during the season.
- Choose medium-aged flowers (all petals present, pollen shed and anthers brown rather than yellow) because more thrips are likely to be found in these flowers.
- Tap each flower sharply onto a sheet of white paper so that any thrips fall out and can be counted.
- Check fruit for thrips damage (bronzing around the seeds).
To access the full report, visit horticulture.ahdb.org.uk.