2021 Lilac-Ash Borer

2021 Lilac-Ash Borer

Landscape & Garden    Treasure Valley

Lilac-Ash Borer Podosesia syringae

Posted on: April 30, 2021 by Nic Usabel

The lilac-ash borer (Podosesia syringae), a clear-wing moth, can be a destructive pest for many species of ash (Fraxinus spp.), previt (Ligustrum spp.), lilac (Sryinga spp.).

The Lilac-ash borers have been caught in traps. Adults are short-lived and typically deposit all eggs within a week after emergence. The first spray should be applied 10-20 days after adult emergence, approximately May 10, before the larvae bore into the trunk. Spray should be applied to the trunk and larger limbs, follow label instructions for application and reapplication depending insecticide selected.

Primary insecticides include permethrin (group 3A), bifenthrin (group 3A) and endosulfan (restricted use; group 2A). Please note that imidacloprid (group 4A), a systemic insecticide, is ineffective against lilac-ash borer and should not be used.

Diversifying species in the landscape, maintaining optimum plant health, monitoring, and preventive sprays (if necessary) are the best methods for preventing infestations. Only preventative treatments exist.

» https://pnwhandbooks.org/insect/hort/landscape/hosts-pests-landscape-plants/ash-fraxinus-ash-borer

» https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1920&context=extension_curall

» https://pnwhandbooks.org/insect/hort/landscape/hosts-pests-landscape-plants/lilac-syringa-ash-borer

» https://extension.colostate.edu/docs/pubs/insect/05614.pdf