Pest or disease?

Causal agent:
Dothistroma septosporum (fungus)

Host species:
A range of conifer species, in particular pines 

Present in the UK?

Tree Alert required?

Dothistroma needle blight is a disease of conifer trees, with pines demonstrating to be the most susceptible species.

It has been spreading across the UK since the 1990’s and is now found throughout the country. Its origin is unknown.

The fungus causes the needles to develop red spots and bands, as the disease progresses the whole needle turns a red-brown colour, while the needle base remains green. This happens in the older needles first, allowing it to be distinguished from frost damage which affects younger needles first. This infection causes the needles to be shed in late summer, continued shedding of needles over a few years can weaken the tree and be fatal. For more information on this disease please see the resources below.