Western flower thrips
Western flower thrips (WFT, Frankliniella occidentalis) are a pest of all the main temperate tree fruit crops. They are known to be particularly damaging to nectarines.
Pest identification
Adult western flower thrips (WFT) are pale brown to yellow, with narrow bodies and are about 1–2 mm long. Western flower thrips are hard to identify in the field and inspection under a light microscope will usually be required to differentiate them from other pest species such as plague thrips and onion thrips.
Damage
WFT damages the skin of certain temperate fruit, including apples and nectarines, by feeding on the fruit surface. As the damaged skin cells grow, the injury develops into a russet, or in apples, the fruit develops an unusual pansy flower-shaped spot.
Monitoring
Monitor for thrips species using yellow sticky traps hung throughout the orchard from bud burst to harvest. The traps will indicate thrips activity and can also be sent to a laboratory to obtain a formal identification of the pest species.
Management
Cultural and physical: controlling established WFT populations will require timely pesticide application. However, several management practices will reduce pest numbers and minimise damage. As broadleaved weeds (particularly clover) are an alternative host for WFT, keep ground cover mown short throughout the year to prevent flowering, but do not mow when fruit trees are in blossom. Choose pesticides that are less harmful to beneficial insects to encourage their presence and survival. Where practical, thin fruit to singles or aim to keep clusters open, as this will make the environment around the fruit less attractive to thrips.
Biological: there are several natural predators of thrips including predatory mites, bugs, lacewings, predatory thrips, lady beetles and parasitic wasps. However, these are unlikely to provide complete control of WFT.
Chemical: registered or permitted chemical options for controlling WFT are limited and differ from those used to manage plague thrips; therefore, correctly identifying the pest thrips species is vital. Refer to the Orchard plant protection guide for chemical suggestions.
