[calendula]

Arbutus unedo tree with all leaves almost black. On closer inspection blackness is a mass of round black spots with a dark edge and dark spot in the middle about .5cm across. Is this black spot fungus of some sort and can it be treated?

Tree is in a group of 4 trees on a grass slope facing south. Close to sea in Kerry. Garden is sheltered from the north and east with large trees.

Soil will be well drained but don't know what type - except it is mostly acidic round here.

[verge]

Any pics calendula
Tutorial here for image adding on this site .... http://www.gardenplansireland.com/forum/about32.html

[calendula]

here is a picture of the leaf. Hope it is clear enough.

[Liparis]

Certainly looks like a fungal attack which started where the rings are. Could have been set off with insect punctures to begin with.
Pick off all affected leaves and burn. The leaves, not the Arbutus.
Bill.

[calendula]

Thanks for your reply. Picking off all the leaves will mean a completely naked arbutus tree. So it looks like there is a case for cutting it down and starting again after a bonfire.

Would that black spot spread to or from nearby roses?

[Liparis]

It may not be the same fungal disease that you get on roses, do you have roses nearby? if so, with that severity, the roses would already be in a sorry state. If the wood on the arbutus is OK, you could remove the leaves, burn them and spray the tree with a fungicide as new leaves appear. I don't know how big your tree is to know if it's worthwhile all the picking. But it's a tree.
Bill.

[James Kilkelly]

I would tend to agree with Liparis there calendula.

Enforce strict garden hygiene around your Arbutus unedo.
Rake out and remove any dead leaves at the base of the trees, destroy these at a safe distance away by burning.
Also, remove any dead or badly damaged leaves on the plants and destroy these as well.
Fungal spores may exist on these dead / damaged leaves and spread the disease through wind and rain splash dispersal.


Reasons why you plant fell foul of this ilness.
An Arbutus unedo plant under stress will suffer more from the effects diseases and viruses.
Burning winds, cold snaps, open wounds, too dry soil, too wet soil, over or under exposure to plant foods, all on there own or any number of combinations will leave a weakened plant ripe for infection.
De-stress your plants by keeping them well watered in dry spells and keeping them fed throughout the growing season.
Apply a pelleted chicken manure once a season; this should be adequate if you have an open, friable soil but it is not effective in heavy, sticky clay soils. In that case, you could also try applying a foliar feed such as Phostrogen or Miracle-gro (when the leaves return).

For now, when you are finished leaf removal give the plants a shake of granular fertiliser for leaf promotion (A feed for hedges, high in Nitrogen) to promote new leafing.

Other Control.
At bud break with a fungicide containing the systemic active ingredient myclobutanil such as Bayer Garden Systhane Fungus Fighter.

Or spray at bud break with the fungicide Captan.

Or else spray at bud break with a fungicide containing the protectant active ingredient mancozeb such as Bio Dithane 945.

Spraying with these fungicides should begin at leaf bud break and continue at approx 7-14 day intervals. But be guided by the labels on the fungicide products.

Good luck.

[calendula]

Thanks for your replies and advise. Will consider options, act and let you know how it goes.