Tree Health News Update - May 2016

19 May 2016

Updates on Oak Processionary Moth, P ramorum, Oriental Chestnut Gall Wasp and Forest Research Calls For Nursery Partners to Help Tackle Phytophthora.

Free downloadable pest and disease guides now available.

Citizen science initiative Observatree has made its downloadable resources and videos available from its website to help you identify priority pests and diseases and spot early outbreaks. They include a pest and disease calendar so you can check at a glance for seasonal issues you should be aware of.

As ever, please report any indication of ill health in trees to us via Tree Alert 

Oak Processionary Moth

The annual programme is under way to control the population, spread and impacts of oak processionary moth (OPM) larvae in London, Surrey and Berkshire.

Tree, landscape and ground-care professionals and others working near oak trees are therefore strongly advised to wear personal protective equipment and to familiarise themselves with the regulations applying to movements of oak material in the affected areas.

You are also ideally placed to supplement the formal surveying by reporting any OPM you see with Tree Alert.

Guidance on all aspects of OPM identification and management is available here, including an OPM manual and a toolkit of resources. 

P. ramorum on sweet chestnut

Forestry Commission are continuing to investigate cases of Ramorum disease in sweet chestnut trees (Castanea sativa) in South-West England, mostly in Devon and Cornwall.

Unlike previous cases of the disease in sweet chestnut, these trees are not standing close to infected plants of other species such as rhododendron or larch.

Please therefore keep an eye out for signs of ill health in sweet chestnut trees now that they are in leaf again, and report suspected cases to FC using Tree Alert. The symptoms are crown deterioration, foliage dieback, wilting and discoloured leaves, premature leaf fall (i.e. before autumn), and characteristic bushy, epicormic growth at the bases of affected trees.

FC are working with Forest Research to understand the disease and its impact on sweet chestnut so that they can provide the best possible advice for growers and owners, and devise appropriate control measures. The numbers of trees affected are relatively small.

FC have published a guide to symptoms and will add to this information as knowledge of the condition develops. 

Oriental Chestnut Gall Wasp (OCGW) Surveillance   

Forestry Commission will be surveying sweet chestnut trees again this summer for any further signs of OCGW in the wake of last year’s discovery of outbreaks in Farningham Woods, near Sevenoaks in Kent, and in St Albans in Hertfordshire.

As well as surveying in and around the outbreak areas, a sample survey of chestnut trees in high-risk areas will be carried out across South-East England and East Anglia.

They ask anyone who owns or lives, works or recreates near sweet chestnut trees to keep an eye out for the tell-tale galls, or growths, which indicate the pest’s presence, and report sightings to us without delay with Tree Alert. Identification guidance is available here 

Forest Research Calls For Nursery Partners to Help Tackle Phytophthora

Forest Research is inviting nursery managers and other plant traders to take part in scientific research into Phytophthora infections in the trade.

The project complements the ‘Keep it Clean’ campaign to promote good biosecurity practice at work to minimise the spread of plant pests and diseases.
Dr Sarah Green, senior forest pathologist at Forest Research, explained,
“As people in the trade are well aware, our plant trade and natural environments are being affected by a range of destructive Phytophthora organisms which have entered Britain from different parts of the world. They arrive and are spread around the country in soil, water, equipment and in the tissues of a large number of plant species, damaging business and ecosystems alike.
“We are looking for plant nurseries and traders to take part in this project to enable us to better understand the dynamics of Phytophthora spread and infection, and devise effective control measures. They can do this by sharing their expertise and experiences with us, and allowing us to sample water and plants at regular intervals during the project.
“In return, we will provide them with information about their Phytophthora risk, and work with them to reduce it. Ultimately the project will provide invaluable data which will help businesses to effectively manage their risk.”
All published data on nursery findings will be anonymous, and it will not be possible to identify any individual businesses from the published findings.
Anyone interested in an informal discussion about ways to get involved may email Dr Green. Further information about the Phyto-Threats Project is available on the Forest Research website