The
biodiversity impact of
Phytophthora infection is
potentially extremely high. Infected bilberry suffers very
extensive dieback. Over 60% of 10km grid squares in the UK
contain native bilberry, and in many areas bilberry forms a
dominant component of the vegetation. Heathlands, acid
woodlands and uplands will be particularly affected. If other
native species, in particular heather, were to become infected then
potential impacts could be even more widespread.
Seven of the Annex I Habitats Directive habitats contain
bilberry as a major component of the vegetation. A large
number of SSSIs contain heathland types as interest features, and
the loss of bilberry would lead these features to be assessed as
unfavourable. A considerable number of species are directly
or indirectly dependent on bilberry. The Phytophagous Insect
Data Bank lists 113 species as feeding on bilberry, bearberry and
heather. 42 appear to be entirely or mainly associated with
the ericaceous shrubs known to be highly susceptible, and three of
these are BAP species (Small Dark Yellow Underwing Anarta
cordigera; Northern Dart Xestia alpicola and Argent
& Sable Rheumaptera hastata - all
moths). Two more another moth, the Scotch
Burnet Zygaena exulansand the possibly extinct shield bug
Elasmucha ferrugata) have British Red Data Book
statuses. Indirect relationships with bilberry include that
of the BAP butterfly, the heath fritillary Melitaea
athalia at some sites.
A number of ecosystem services would be likely to be impacted by
the loss of a dominant habitat component such as bilberry or
heather. Recreational services would be particularly
affected. Additionally, soil stability and hence water
quality could be affected, as well as primary production, nutrient
cycling and food provision.
Impacts of control measures
Currently there are no known mechanisms for controlling
Phytophthora on bilberry. Control of the disease is
normally by destructive measures, i.e. by removing all infected
plants. Whilst there could be positive impacts for
biodiversity if Rhododendron is removed from wild sites,
removal of native infected species could be devastating.