Volunteer activity
Number of hours recorded: 14,971.5
Number of tree health site surveys completed: 3,729
Number of site surveys which found a pest of disease: 1,315
Number of site surveys which found a suspected Observatree priority pest or disease: 858
Priority pest and disease findings
- Acute oak decline
- Chalara dieback of ash
- Dothistroma needle blight
- European mountain ash ringspot virus
- Great spruce bark beetle
- Horse chestnut leaf miner
- Oak processionary moth
- Oriental chestnut gall wasp
- Phytophthora austrocedri
- Phytophthora lateralis
- Sirococcus tsugae
Other key findings
- Sirococcus conigenus
- Dutch elm disease
- Phytophthora alni
- Oak powdery mildew

Tree Alert reports submitted between the start of October 2017 to the end of June 2018
Tree Alert enquiries by country (total 864)

Top 5 host tree species in order:
Ash
Oak
Sweet chestnut
Hawthorn
Elm
Top pathogen reported: Chalara
Top pest reported: Oak processionary moth