Troubleshooting
Rossica Major rowan problems — and how to fix them
Rossica Major rowan (Sorbus aucuparia 'Rossica Major') is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Fireblight (Erwinia amylovora)
Blossoms and shoot tips blacken and wilt in warm, wet spring conditions. Prune back well into clean, healthy wood; sterilise all cutting tools between cuts. Maintain tree vigour through good drainage and balanced nutrition.
Sorbus rust (Gymnosporangium cornutum)
Orange-yellow pustules on the undersides of leaves; requires Juniperus communis as an alternate host nearby to complete its life cycle. Remove infected juniper plants in proximity; apply a copper fungicide in early spring if recurring. Rarely causes serious tree damage.
Aphids (Dysaphis sorbi)
Rowan–parsley aphid causes leaf curl on young shoots in spring. Populations generally collapse naturally by early summer as natural predators establish. A winter plant oil wash controls overwintering eggs on persistent problems.
Prevent rossica major rowan problems before they start
Most rossica major rowan issues are care-mismatch, not bad luck. Dial in the basics:
Rossica Major rowan problems — FAQ
Why is my rossica major rowan fireblight (erwinia amylovora)?
Blossoms and shoot tips blacken and wilt in warm, wet spring conditions. Prune back well into clean, healthy wood; sterilise all cutting tools between cuts. Maintain tree vigour through good drainage and balanced nutrition.
Why is my rossica major rowan sorbus rust (gymnosporangium cornutum)?
Orange-yellow pustules on the undersides of leaves; requires Juniperus communis as an alternate host nearby to complete its life cycle. Remove infected juniper plants in proximity; apply a copper fungicide in early spring if recurring. Rarely causes serious tree damage.
Why is my rossica major rowan aphids (dysaphis sorbi)?
Rowan–parsley aphid causes leaf curl on young shoots in spring. Populations generally collapse naturally by early summer as natural predators establish. A winter plant oil wash controls overwintering eggs on persistent problems.