Pest or disease?
Disease

Causal agent:
Emaravirus (plant virus)

Host species:
Rowan (mountain ash)

Present in the UK?
Yes

Tree Alert required?
Yes

European mountain ash ringspot-associated virus, or EMARAV, is a plant virus that infects mountain ash trees.

Not much is known about the virus or its origin. It may also infect trees in association with mites, but more research is required.

The virus causes discoloration and mottling of the leaves, in the early stages of infection this can look more like chlorotic speckling. The trees productivity can be reduced, meaning it becomes more susceptible to other damaging factors. For more information on EMARAV please see the resources below.