OPAL

Tree Health

Survey Training

May 2013

• Introduction to UK forests and Tree Health

• Pests and Diseases

• Conducting the survey

• Practical Training

Session Structure

Introduction to Trees and Tree Health

Trees are good for our wealth, health and happiness both now and in the future.

The Value of Trees

Economy Wellbeing Biodiversity

Climate Change National Heritage

• Trees have a life cycle• Usually trees are healthy • An increasing number of new pests and diseases are

attacking trees in the UK• Increasing world trade and climate change are two contributory

causes for the increase

Tree Health

What is happening?

The Government works to protect the country from pests and diseases by:

o Plant health legislationo Inspecting imports o Inspecting woods and plant nurserieso Campaigns to eradicate outbreakso Conducting researcho Raising people’s awareness

What we can all do to help:o Public engagement assists with surveillanceo This is where OPAL fits in… We need your help!

Previous OPAL Surveys: The Tree Health Survey:

OPAL Surveys

Soil and Earthworm

Air Biodiversity

Water Climate Bugs Count

Pests and Diseases

What are plant pests and diseases?

Pests: usually invertebrates

(insects, mites, nematodes)

Diseases: caused by pathogens

(fungi, bacteria, viruses)

Survey will focus on 18 pests and diseases

Introduction to Pests & Diseases

2003 2005

2011

Horse Chestnut Leaf MinerChalara ash dieback

Monitoring pests and diseases affecting Britain’s trees aids our understanding of their impact, their changing distribution and helps to manage their spread.

For Example:

Why Research thesePests & Diseases?

Knopper Gall wasps (Andricus quercuscalicis) arrived in southern England in the 1950s and have now invaded most of the UK.

• Ridged and knobbly protrusions on acorns (from July onwards) caused by a tiny gall wasp

• Does not kill tree but affected acorns cannot germinate

OAKKnopper gall

The roller moth, Tortrix viridana, is a native species of micromoth.

• Loss of leaves in May and June• Edges of leaves curled up into a tube

• Heavily infested trees can be completely defoliated• There are other native defoliators on oak

OAKTortrix roller moth

• Attacks young leaves and soft shoots, covering them with felty-white mycelium and dry powdery spores

• Leaves may shrivel and blacken• Mild overcast conditions are optimal for

development of the disease, usually appears in summer

Erysiphe alphitoides is a common foliar fungal pathogen of oak throughout Europe. First found in England in 1908, it contributed to an oak dieback episode the 1920s.

OAKOak powdery mildew

Oak decline is a complex disorder: Several damaging abiotic (e.g. drought) or biotic (e.g. insects and fungi) agents interact. It can be simultaneous &/or sequential and outcome can be a serious decline in tree health, may be terminal, but trees can also recover.

Not a new disorder but recently we have come to recognise:• Chronic Oak Decline (COD): slow effect about 10-50

years, focus on roots

• Acute Oak Decline (AOD): fast effect approximately 3-5 years, focus on above ground parts

OAKOak decline

Serious episodes of oak decline have been documented for almost 50 years in the UK.

• Early signs are yellowing or fewer leaves

• Later, dead branches can be seen• Severe cases, dark weeping

patches on trunk which dry to black crust

• D shaped holes in trunk bark• Canopy dieback and /or thinning• Bacterial lesions Agrilus beetles

OAKAcute Oak decline

Photograph courtesy of Nigel Straw, Forest Research

• Sparse foliage• Wilted and blackened leaf

shoots (May onwards)• You mat find entrance / exit

holes in buds and at base of wilted shoots

• Silken webs and frass (fragments of bark) may also be visible

• Symptoms most obvious on younger trees

The ash bud moth Prays fraxinella, is a native species of micromoth.

ASHAsh bud moth

• Look for a woody encrustation on the stalk of the ash keys

• Galls are green at first becoming brown later

• Older galls can remain attached for over a year, so visible for year round

• The galls make ash keys heavier so wind dispersal is hindered

Also known as cauliflower gall, it is caused by the eriophyid mite Aceria fraxinivora.

ASHAsh key gall

Photograph courtesy of Nigel Straw, Forest Research

• New cankers look like a depression on the trunk or branches

• Causes death of twigs• Centred on small branch stubs or their

remains• Older cankers look like a target: concentric

rings of dead wood

Nectria canker is caused by the fungus Neonectria galligena. It is a native disease which may be linked to existing wounds, causing dieback of twigs and sometimes branches to break.

ASHNectria canker

Ash decline is caused by a combination of factors that affect the roots and causes a gradual decline in the tree.

• Death of a number of twigs and branches

• Poor growth in the crown • Common in hedgerow trees

beside ploughed fields, especially on drier sites

• Dieback is progressive over a number of years.• Recovery is possible and trees take on appearance of a healthy crown with

some dead branches

ASHAsh decline

• Red-brown blotches on leaves, outlined in yellow

• Hold the leaf up to the light – blotches are not translucent

• Blotch spreads across leaf veins

• Disfigures but does not kill tree

• May appear in combination with Horse Chestnut leaf miner

Photos courtesy of Nigel Straw, Forest Research

Caused by the fungus Guignardia aesculi, this disease was first reported in Britain in 1935.

HORSE CHESTNUTLeaf blotch

Horse chestnut leaf miner

• Brown blotches on upper or lower surface of leaves

• Hold the leaf up to the light – blotches are translucent

The micro moth, Cameraria ohridella arrived in the UK in 2002 from Europe. Ten years after the pest was first seen in Wimbledon those trees remain in good health.

HORSE CHESTNUTLeaf miner

• Mines constrained by leaf veins

• May appear in combination with Horse Chestnut leaf blotch

• Severely damaged leaves shrivel and turn brown in late summer

HORSE CHESTNUTLeaf miner & Blotch

• Rusty coloured liquid oozes from trunk bark

• Liquid dries to black crust at point of exit

• Severely affected trees have thinning crowns with dead branches

• Severe attacks can kill trees

• Bark killing may be so extreme that damaged bark peels of tree exposing wood beneath

Photos courtesy of Nigel Straw, Forest Research

Caused by the bacterium Pseudomonas syringae pathovar aesculi, this disease suddenly appeared in the early 2000s.

HORSE CHESTNUTBleeding canker

• Circular white spots topped with brown or orange on trunk or branches

• Found on many tree species including Horse Chestnut, Sycamore and Lime

• Visible in May and June• Disfigures but does not kill tree

Caused by the insect Pulvinaria regalis, first found in Britain in 1964

HORSE CHESTNUTScale

Most Unwanted

Chalara fraxinea emerged as an entirely new disease in Europe in the 1990s and first found in Britain in 2012.

• Stem lesions typically centred on side branch infection

• Death of twigs and branches

• Girdling of shoots and stems resulting in dieback, young trees particularly vulnerable

• Common ash (Fraxinus excelsior) very susceptible

H. pseudoalbidus fruit bodies on

fallen ash

MOST UNWANTEDChalara Ash dieback

• Initial thinning and yellowing of foliage

• Tunnels made by larvae in the bark have sharp bends and meanders

• Bark has narrow fissures (cracks) about 5-10 cm long, caused by scar tissue produced by tree after larval feeding

• D shaped holes (c.3mm diameter) produced in trunk by emerging adults

Photos courtesy of Nigel Straw, Forest Research

Agrilus planipennis is NOT present in UK, its arrival would be a cause for great concern.

MOST UNWANTEDEmerald Ash Borer

Photos courtesy of Nigel Straw, Forest Research

Thaumetopoea processionea is present in London and areas of Berkshire.

• Caterpillars cause defoliation• Caterpillars show distinctive

habit of moving about in late spring and early summer in nose-to-tail processions

• Build distinctive white, silken webbing nests in oak trees and leave white trails up stem

MOST UNWANTEDOak Processionary Moth

Causes human health problems AVOID any contact!

• Caterpillars cause defoliation of needles

• Most distinctive life stage is the caterpillar, which is coloured orange-brown with blue bands covered in dense clumps of hairs. Wedge shaped procession moving nose-to-tail

• Caterpillars most likely to be seen winter and early spring. Overwinter in tent-like like nests high in Pine trees

Thaumetopoea pitycampa NOT present in UK.

MOST UNWANTEDPine Processionary Moth

Causes human health problems AVOID any contact!

March 2013

• Infest a wide variety of tree species, especially Poplar, Sycamore and Willow.

• Adults are black shiny, 20-35 mm long and 7-12 mm wide with about 20 irregular white spots

• Distinctive long antennae. Antennae segments are black with distinctive blue-grey/creamy-white base.

• Circular breeding exit holes are up to 10 mm in diameter, usually higher on the trunk than the Citrus Longhorn Beetle

Recent outbreak of Anoplophora glabripennis in Kent was eradicated, so NOT present in UK. Would be a major threat if they became established.

MOST UNWANTEDAsian Longhorn Beetle

• Very similar in appearance to the Asian Longhorn beetle

• Could infest a wide variety of tree species, especially maples

• Adult beetles are large and black with variable white markings

• They have very long antennae which are black with white/light blue bands

• Circular breeding exit holes 5-10 mm in diameter have been found on maple saplings, usually near the base of the trunk

Anoplophora chinensis is NOT present in UK. Would be a major threat to horticulture and the wider environment if they became established.

MOST UNWANTEDCitrus Longhorn Beetle

Conducting the survey

• Check the website

• Read the instructions

• Landowners

permission

• Health and safety

Before You Begin…

http://www.opalexplorenature.org

Health and safety

All the equipment that you need is in the pack, which contains:

Field Notebook Field Guide

Fold Out Tree Guide

Most Unwanted Guide

Tape Measure

Optional Equipment:

Camera

OS Maps or GPS

Smart Phone

Equipment

Pencil

Tree Identification

Activity 1 can be carried out on any tree, but preferably on Oak, Ash or Horse Chestnut.

Activity 1

This activity can be done on Oak, Ash or Horse Chestnut only.

• Ideally survey the same tree as used in Activity 1• Use the field guide to identify whether your tree

has any of the four pests/diseases of your chosen tree species

Please take a photo if you think you identify any of the pests/diseases on your tree

Activity 2

This part of the survey can be done on any tree, and at any time

• Results can be submitted independently of the rest of the survey

• Use Most Unwanted guide to help with identification

• Health and safety • Bio-security guidance

Take a photo of the Most Unwanted and submit via the OPAL website or the Tree Alert App/ webpage…

http://www.forestry.gov.uk

Most Unwanted

• Submit via the OPAL website or freepost address

• Activity 1, 2 and 3 results can be submitted independently

• Photos

• Record your location accurately

It’s really important that you send us your results once you have done the survey.

Submitting Data

Good crown density, leaf colour and no signs of other damage = tree is in good overall condition

High levels of defoliation and/or discoloured leaves

= tree will grow at a slow rate

Oak decline and ash decline = tree is suffering a range of problems

Weather events, climate change and human activity = influence the geographic distribution of common tree pests and diseases

Reports of our ‘Most Unwanted’ pests = track the arrival and spread of quarantine species

What does your data mean?

Practical Training

Outdoor Exploration of the Tree Health Survey…

Thank you… Questions?

Photos courtesy of Forest Research and Fera