Western Australian rose growers are getting ‘hot under the collar’ trying to protect their plants from another garden pest – chilli thrips.
Chilli thrips (Scirtothrips dorsalis) are found throughout the world and were first reported in the State’s north about 20 years ago.
The Department of Primary Industries and Regional Development has been inundated with reports of the pest from the metropolitan area over the past few weeks.
Acting Deputy Chief Plant Biosecurity Officer Darryl Hardie – aka Dr Bug-a-lugs – said department testing had confirmed damage to samples were caused mainly by the chilli thrips and not a viral threat.
“The recent rainfall and humidity has created conditions that are conducive to chilli thrips, which like to feed on the sugars in new shoots,” Dr Hardie said.
“Chilli thrips have moved down from the north of the State to the south in recent years and have been very active during the past few weeks in Perth gardens.
“Also known as strawberry thrips and tea thrips, chilli thrips feed not just on roses but also on all citrus and their hybrids, as well as a range of fruit and vegetable hosts.”
Chilli thrips can be controlled via a range of products registered to treat other species of thrips.
Dr Hardie urged gardeners to inspect their plants for damage symptoms and take immediate action to minimise the pest’s impact.
“Once you see damage to your plants it’s almost too late to take preventative measures so gardeners need to act when thrips first arrive,” he said.
“Plants infested by chilli thrips have damage similar to that caused by other thrips species, such as wrinkled leaves with distinctive brown scarring along the veins of the leaves, flower buds and the calyx or outer casing of fruit.
“An option is to encourage new growth by doing a hard prune of infested plants to remove damaged plant material, making sure to bag the offcuts before binning to prevent the pest from spreading.
“Multiple applications of treatments, whether organic or not, will probably be required and it may be wise to apply treatments to other nearby host plants to protect them from the pest.”
Chilli thrips are tiny and difficult to distinguish from other thrips species with the naked eye.
The pest is about two millimetres long, pale or translucent in colour with an elongated body.
More information and advice on how best to control thrips on ornamental plants is available from local garden centres.
Picture caption: The brown, curled leaves of a rose infested with the pest chilli thrips, which has plagued Perth gardens in recent weeks.
Source: WA DPIRD