Troubleshooting
Manna Ash problems — and how to fix them
Manna Ash (Fraxinus ornus) 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.
Ash dieback susceptibility
Fraxinus ornus shows some resistance to Hymenoscyphus fraxineus compared to F. excelsior, but is not immune. Monitor for wilting shoot tips and diamond-shaped bark lesions. Remove infected wood promptly. Research into using F. ornus in breeding tolerant hybrids is ongoing.
Lilac borer / Ash borer (Podosesia syringae)
Larvae bore into the main trunk and large branches, weakening structure. Entry points are masked by sawdust-like frass. Maintain tree health; avoid wounding bark during mowing or strimming. Remove and destroy heavily infested branches.
Poor flowering in shade
Unlike other ash species, F. ornus relies on insect pollination and produces conspicuous flowers — but these fail or are sparse if the tree is sited in shade. Ensure an open, sunny position is chosen at planting, as remedying this later is difficult.
Prevent manna ash problems before they start
Most manna ash issues are care-mismatch, not bad luck. Dial in the basics:
Manna Ash problems — FAQ
Why is my manna ash ash dieback susceptibility?
Fraxinus ornus shows some resistance to Hymenoscyphus fraxineus compared to F. excelsior, but is not immune. Monitor for wilting shoot tips and diamond-shaped bark lesions. Remove infected wood promptly. Research into using F. ornus in breeding tolerant hybrids is ongoing.
Why is my manna ash lilac borer / ash borer (podosesia syringae)?
Larvae bore into the main trunk and large branches, weakening structure. Entry points are masked by sawdust-like frass. Maintain tree health; avoid wounding bark during mowing or strimming. Remove and destroy heavily infested branches.
Why is my manna ash poor flowering in shade?
Unlike other ash species, F. ornus relies on insect pollination and produces conspicuous flowers — but these fail or are sparse if the tree is sited in shade. Ensure an open, sunny position is chosen at planting, as remedying this later is difficult.