Tree Stem Injection NSW — In-House Pest, Disease & Nutrient Treatment for Heritage and High-Value Trees

The main arboricultural applications, in rough order of frequency in our practice:

• Elm Leaf Beetle (Pyrrhalta luteola) on heritage elms — our most-common application, treated with Bayer Silvashield (active ingredient imidacloprid)
• Other foliar-feeding insects — aphids, scales, lerps and similar pests on trees too large or environmentally sensitive for canopy spray, also treated with systemic insecticides like Silvashield where appropriate
• Borer infestations — longicorn (longhorn) beetle, cossid moth, fruit-tree borer and similar wood-boring insects, treated with appropriate registered systemic insecticides
• Phytophthora and related root pathogens — treated with injected phosphite (phosphorous acid)
• Nutritional deficiencies — iron chelate for chlorosis being the most common
• Some fungal canker diseases where systemic fungicides have demonstrated efficacy

Stem injection does NOT treat structural defects, mechanical damage, drought stress (other than as part of broader management), or pathogens for which no systemic chemistry is registered.

Injection technique is designed for minimum-impact entry. The injection points are small (typically 3–6mm depending on the injection system) and at low density around the stem circumference. Trees in good general health compartmentalise the entry points within weeks. For trees in poor condition with compromised compartmentalisation, the injection technique is selected to minimise impact — some systems are designed specifically to leave smaller entry points than the older bore-and-port methods they replaced.

Depends heavily on the chemistry, the target pest/disease, and the tree’s vascular activity. Some treatments (e.g. iron chelate for chlorosis correction) may need annual repetition. Some borer treatments persist 2–3 years against active infestation. Some phosphite root-pathogen treatments are maintained on biennial or annual cycles depending on disease pressure. We’ll specify the expected treatment cycle at the diagnosis stage so the engagement structure matches the ongoing requirement.

Our main injection product is Bayer Silvashield — APVMA-registered for stem-injection use, with active ingredient imidacloprid (a systemic neonicotinoid insecticide). Silvashield is our primary tool for Elm Leaf Beetle control on heritage elm trees, with broader systemic insecticidal effect against aphids, scales, lerps and other foliar-feeding pests where appropriate. For other targets — Phytophthora root rot (phosphite/phosphorous acid), nutritional deficiencies (iron chelate and similar), specific borer chemistries (where Silvashield isn’t the right tool) — we use the relevant registered product selected at the diagnosis stage. All products applied to APVMA label specifications, with brand and active ingredient documented in the treatment record.

Sometimes yes, sometimes no, sometimes only partially. Stem injection is most effective early in a pest or disease progression — before the tree’s vascular function is so compromised that systemic delivery itself becomes unreliable, and before structural damage from the pest exceeds what the residual tree can support. For heavily declined trees, injection may slow further decline without restoring full canopy; in some cases the diagnosis will confirm that removal is the better call. We’ll give an honest assessment at the diagnosis stage rather than treating trees that can’t reasonably recover.

Generally yes, for several reasons. No spray drift — the active ingredient stays in the tree being treated, not in the air column or on adjacent vegetation, water bodies, residences. No soil contamination — nothing applied to the soil profile where it could affect non-target soil organisms or leach to groundwater. Low non-target impact on pollinators — systemic chemistries inside the tree are accessible to insects that feed on the tree but largely unavailable to insects that visit flowers, with the caveat that this varies by chemistry and timing. Lower applied quantity overall vs canopy spray for the same tree. The trade-off is the small injection entry points on the tree itself, which is typically a fair exchange for the wider environmental benefit.

Stem injection is generally considered tree-care work rather than tree-impact work, so most councils don’t require formal approval for injection of TPO-listed trees — but provisions vary by council. Where council notification or approval is required, we’ll document the proposed treatment in a form council can review and recommend the right council engagement. For heritage-listed trees, additional approvals may apply under the Heritage Act — we’ll flag at scoping.

Australian APVMA-registered products applied according to their label conditions (this is a legal requirement, not just best practice). Arboriculture Australia Minimum Industry Standards for the application practice. ISA TRAQ for the underlying risk-and-condition framework where injection sits within a wider risk-management strategy. AS 4970-2025 where injection intersects with retained-tree protection on development sites.