Red Tip Photinia Trunk Damage: Borers, Cankers, or Something Else?

Diagnosing Circular Bark Lesions on Photinia

Red tip photinia (Photinia × fraseri) with expanding circular trunk lesions—described as bore holes that widen 6–8 inches up the trunk—warrants careful investigation. The absence of leaf spots, weeping, or visible insects narrows the possibilities.

Likely Causes

• Wood-boring insects: Flatheaded borers (Chrysobothris spp.) or clearwing moths (Synanthedon spp.) leave round entry holes and push frass (sawdust-like excrement). Larvae feed in cambium, girdling stems.
• Fungal cankers: Botryosphaeria or Nectria cankers create sunken, target-shaped lesions with cracked bark margins. Often follow stress (drought, freeze, mechanical injury).
• Mechanical damage + secondary decay: String-trimmer or mower wounds invite decay fungi that expand circumferentially.

Diagnostic Steps

1. Probe the holes: Insert a stiff wire to check for larvae or frass.
2. Scrape bark at lesion edge: Look for discolored cambium (brown/black = dead; green = live) and fungal fruiting bodies (tiny pimples).
3. Photograph and consult: Send clear images to a local extension agent or ISA arborist for definitive ID.

Management

• Borers: Remove and destroy infested stems. Apply preventive bark spray (permethrin or bifenthrin) in spring when adults emerge. Maintain vigor with watering/mulching.
• Cankers: Prune 6–12 inches below visible canker into healthy wood. Sterilize tools between cuts. Improve drainage and avoid wounding.
• General: Mulch 2–3 inches, keep away from trunk. Water deeply during drought. Fertilize lightly in spring if growth is poor.

Without a photo, a precise diagnosis isn’t possible, but the described symptoms strongly suggest either borers or a canker disease—both treatable if caught early.