Trees Diseases

Developed by:Frank Reilly, Advanced Master Gardener Volunteer

in cooperation with:Chuck Hoysa, Past Extension Agent and Soil & Water Conservation

District EducatorJoe Murray, Consulting Arborist and Assistant Professor of Biology

Arboriculture Program Director, Blue Ridge Community CollegeMila Pearce, IPM Diagnostic Lab, &

Gary Peiffer, County Extension Agent, The University of Georgia

Cooperative Extension

Non-Living Factors

Often cause disease-like symptoms

AND contribute to disease susceptibility

Janet will cover this aspect Nutrient Deficiency Water Stress Temperature Stress Other

Conditions Necessary for Plant DiseasePathogen Susceptible

Host

Favorable Environment

Telephone call to Cooperative

Extension!

Take Home Message

Right Plant Right Place If you paid attention to the rest of these

classes you can ignore most of the rest of this talk.

Diagnosis Accurately ID the plant – THE MOST

important step! Look for patterns of abnormalities

Diagnosis

Examine the site

Diagnosis

Look at the foliage

Diagnosis

Look at the trunk and branches

Diagnosis

Look at the roots and root collar

Diagnosis

Symptoms vs. signs Symptoms - expressions of disease

initiation that differentiate them from healthy plants nearby

Signs - vegetative or fruiting (reproductive) structures of the organism that is causing the disease

Disease Symptoms

Spots - circular or irregular lesions on leaves, flowers, and stems

Blights - sudden death of leaves, flowers, and twigs

Galls - abnormal growths or swelling Cankers - dead places on bark and stems Rots - general decomposition of tissue

Insect DamageLeslie will talk about this

Some insect damage can look like disease

Sooty mold - grows on honeydew

Scales, mealybugs, mites, adelgids, borers can all cause damage that looks like disease

Top 10 Diseases

You are “likely” to encounter.

Powdery mildews: Found world wide Over 7000 species Gymnosperms are not infected Obligate parasites

Powdery mildews: *Found world wide *Over 7000 species *Gymnosperms are not infected *Obligate parasites

Favorable conditions:*Dry, warm days*Cool nights*Water inhibits germination,

but humidity does not

Anthracnose: Fungal disease of a wide variety of broad-leaved trees causing symptoms that vary from small necrotic leaf spots to blight of leaves.

Primary causal agents:ColletotrichumKabetiellaPhyllostictaGloeosporiumDisculamany more…..

Discula on Dogwood

Dieback caused by Discula Discula petal blight

Control: Anthracnose on some species is not warranted because of location or the disease presents no long term damage. Maintain tree vigor with proper watering, fertilization, good drainage, etc.Valuable shade trees may be pruned to reduce severity and increase life span of the tree.

Septoria leaf spot - circular spots formed when a fungus attacks at bud break. Control should therefore be attempted at that time. Septoria species attack a wide variety of trees.

Fire blight - common to several Prunus species greatest damage on apples, crabapples and pears

Symptomology:Sudden blighting, death of bloomsBacterial ooze may be visibleBlighted leaves stay attachedForms shepard’s crook

Control: Plant tolerant varieties Prune infected branches Disinfect pruning tools Maintain plant vigor Control insect vectorsSprayed on antibiotics are also recommended but they are very costly and the coverage and timing are the keys to any success.

Cankers and Galls on trunks/branches - Seiridium Canker

Distinct, sunken lesions which lead todieback and death

Spores are dispersed throughoutthe summer, but infection periodsare unknown

Hosts include :Oriental arborvitaeBaldcypressArizona cypressItalian cypressLeyland cypressJunipers

Dieback is from the inside out

Flattened cankers are associated with bleeding and resin.

Control:

Remove cankers in winterDo not prune in May or JuneIncrease plant healthNo chemicals available

Phomopsis Tip Blight – Disease of conifers causing needle cast, dieback, and death of highly susceptibletrees.

Control:Fungicides can be effective if applied according to label directions. Pruning branches will limit inoculum build-up.

Black KnotCommon gall on cherries,plums, and peaches.

Symptoms include dieback of branches, thin crowns, and gnarly black galls on trunkor branches.

Control: Prune branch galls six to eight inchesbelow infection. It is impractical to remove trunkgalls.

Wetwood and SlimefluxCaused by bacteria.Hosts:OaksPopularElms

Other symptoms:fermentation smell, swarming insects

Wetwood or slime flux •bacterial infection •initiated through root and/or trunk wounds. •Oozing occurs when bacterialpressure builds up•Trunk and bark staining usually results.•weakens trees but does not directly cause their death.

Control:•Cosmetic only.•Use 10-20% bleach solution•clean the bark surface.•Do not drill to insert drain tubes•That spreads infection.

Wood Decay FungiGanodermaInonotusHypoxylonHispidus CankerIrpex Canker

Hypoxylon Canker

Symptomolgy:Symptomolgy:Slighty sunken irregular areas on barkSlighty sunken irregular areas on barkCanker becomes blistered with clusters of perithecia Canker becomes blistered with clusters of perithecia

immersed in stromata causing the tree bark to exfoliate.immersed in stromata causing the tree bark to exfoliate.Colors vary from black, gray to tan.Colors vary from black, gray to tan.

Hypoxylon canker is most prevalent in situations of weakened or stressed hardwoods.

Hosts:OakBeechHickoryMaplesTupelo

Control measures include pruning out branch cankers, surgically removing small trunk cankers, fertilizing and watering to improve tree vigor. These controls can slow disease spread but do not often totally eliminate it!

Hispidus Canker

Entry point for this fungus is usually through old branch stubs or wounds. Causes a soft, white heart rot.

Hispidus CankerPrimarily found on oak species

Once trunk decay fungi are actively growing, there is no control. Improve tree vigor to add to its lifespan!

Vascular WiltsDiseases that interfere with theuptake and flow of waterand nutrients.

Verticillium WiltSample Hosts:Maple, Ash, Elms, Magnolia, RedbudTulip Poplar

Symptoms include:•curling,•drying, •interveinal chlorosis

or•reddening, •defoliation, •wilting, •dieback and death.

•Infection occurs on stressed trees •initiated through the roots and wounds.

Dutch Elm Disease DEDYellowing, flagging and branch dieback

Staining under bark

Control:Prune infected branches and monitor insect vectors (elm bark beetles).Prevent root grafts through appropriate use of trenching methods.Plant resistant varieties such as Chinese Elms and Zelkova Elms.

Annosum Root RotPrimaryHosts:CedarHemlockPinesSymptoms include generaltree decline and wind-throw.

What Next?

Most diseases we encounter are cosmetic Sanitation - prune and rake Remove problem trees Plant appropriate or disease resistant

trees Spraying is often not an option Get a positive ID before any treatment Start with a good sample

What makes a good sample?

Distinct symptoms Fresh sample Whole section of

branch or handful leaves

Junction of live and dead tissue

What plant is it!

What makes a bad sample? All dead tissue Single leaf Been on dashboard

for a week Damage occurred

months ago Don’t know what

plant it is

HOW AM I DOING ON TIME?

Some Cool Ones to Know

Oak Leaf Blister (caused by a fungus) is more common during cool, wet springs. Leaves remain attached therefore little long term harm to tree.

Witches’ Broom caused by powdery mildew on Witchhazel but there are many causes such as diseases, insects, frost, drought, etc.

Witches’ Broom caused by mites and powderymildew on Hackberry tree.

Galls are abnormal growth responses caused by fungi, insects, and bacteria

Cedar Apple Rust

Mature gall

Actively sporulatinggalls

Alternate host leaf spot.Most often seen on apples and crabapples.

NEW DISEASES ON THE HORIZONSudden Oak Death, SOD, Phythophthora ramorum

Phythophthora ramorum is a soil-borne fungus

accidentally shipped to the Eastern USA in nursery stock

shown to affect over 60 different ornamental plants.

damaged and/or killed many western tree species but

we do not know what it will do to eastern varieties, especially our oaks.

www.suddenoakdeath.org

Trees Pests

Developed by:Leslie Paulson, Advanced Master Gardener Volunteer

in cooperation with:Chuck Hoysa, Past Extension Agent and Soil & Water Conservation

District EducatorJoe Murray, Consulting Arborist and Assistant Professor of Biology

Arboriculture Program Director, Blue Ridge Community CollegeMila Pearce, IPM Diagnostic Lab, &

Gary Peiffer & Jule-Lynne Macie, County Extension Agent, The University of Georgia

Cooperative Extension

Insect Damage

Some insect damage can look like disease

Sooty mold - grows on honeydew

Scales, mealybugs, mites, adelgids, borers can all cause damage that looks like disease

Insects are often blamed for other’s damage: Sapsuckers Herbicide damage Lightning Too much or not

enough water Squirrels, roof rats String trimmer

Beaver Deer

Secondary pests Ants Bees Long horned beetles Termites

When looking at damage:

Think mouthparts Holes – chewing Wilting, yellowing – piercing sucking Speckling – rasping sucking

The Real Boring Insects

Chewing mouthparts, so think ‘holes’

Bark Beetles

3 different beetles – southern pine beetle, Ips engraver, Black turpentine

Needles turn yellow from tips back

Larvae feed under bark

Under the Bark

Beetles attack stressed native pine trees

Second generation beetles attack surrounding trees

Blue stain fungus Galleries

Pitch Tubes

A sign of attack. Beetles are

sometimes ‘stuck’ in pitch

Control for Homeowners

Sanitation! Homeowners do not

have equipment to spray preventatively

Asian Ambrosia Beetles

Attack smooth bark trees in early spring when leaves expanding

Bore deep into heartwood

Need moist wood Toothpicks No good chemical

control Cut down

Various Wood Boring Beetles Attack various

trees Female lays eggs

on trunk and larva bore under bark

E.g. Poplar Borer, Emerald Ash Borer, Lilac Borer, Bronze Birch Borer

Emerald Ash Borer

aggressive wood borer Responsible for fire wood

quarantine “D”-shaped exit hole

Caterpillars

Chewing mouthparts so think ‘holes’

Bagworms

Deciduous and evergreens

Insecticides only if early in season

Fall – move to ends of branch and pupate

Males fly to females Lay eggs in bag Prune and discard!

Tent Caterpillars Spring pest Tents in interior of tree Prefer fruit trees Pretty caterpillars Capable of total

defoliation Will not kill a tree

(usually)

Orange Striped Oakworm

Fall Pest of Oaks Caterpillars feed

together Begin life light green

and turn black with stripes

Fall Webworms fall webworm

appears I late summer

nests grow until entire branches are covered

Seldom a danger to the tree

Hickory Horned Devil

Regal Moth Largest

Butterfly/moth north of Mexico

Beetles

Both adult and larvae can cause damage

Japanese Beetles

Turf pest Adults difficult to

control Attack the grubs

Sucking Insects

Needle-like mouth so think yellowing, wilting and deformity

Bark Aphids

Wooly Alder Aphids Piercing sucking Suck plant sap Honeydew Sooty mold 30 generations a

year Live birth Wings at times

Aphids in general

Clients will often say their problem is ants on their plants

Aphids like tender Nitrogen rich plant tips

Can cause mildew due to sweet honeydew

Natural controls (e.g. lady beetles)

Scales – Soft, Armored, Pit, Oystershell, etc.

Piercing sucking Crawlers – only

control stage Waxy covering Systemic

insecticides Sooty mold

Other Insects

Miscellaneous damage, but is it really necessary to control?

Galls                          

Leaf Miners Death to plant uncommon

Discolors or browns leaves

Hard to control – remove fallen leaves

Time applications exactly

Cicadas Annual Periodic No long damage

except to young saplings

Flagging Different species (at

least 3) Different broods

                                        

Lacebugs Oak Sycamore Hawthorn Azalea,

rhododendron    

The End

Any Questions?