People planning to go walking
or cycling in the Brecon Beacons have been asked to take steps to avoid the potential spread of a fungal disease that is harming trees in the national park.
An outbreak of Phytophthora ramorum has occurred in the upper Taf Fechan and Talybont valleys, on land owned by the Forestry Commission.
Public access is still being permitted for now, but visitors have been asked to clean off any dirt or mud from their walking boots
and mountain bikes
before they make any return visit, to reduce the risk of spreading the disease.
Conservation manager for the national park authority Paul Sinnadurai said: "Our wardens are working with Forestry Commission Wales to take all necessary precautions (cleaning clothes, boots and disinfecting too) when entering infected woodlands."
He asked the public to take similar steps.
Environmental concerns in the national park this year have also included an outbreak of blue-green algae in Llanghors Lake, although this eased enough for the public to be permitted to enjoy water-based activities there again in July.