Trees Diseases Developed by: Frank Reilly, Advanced Master Gardener Volunteer in cooperation with: Chuck Hoysa, Past Extension Agent and Soil & Water Conservation District Educator Joe Murray, Consulting Arborist and Assistant Professor of Biology Arboriculture Program Director, Blue Ridge Community College Mila Pearce, IPM Diagnostic Lab, & Gary Peiffer, County Extension Agent, The University of Georgia Cooperative Extension
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Trees D iseases Developed by: Frank Reilly, Advanced Master Gardener Volunteer in cooperation with: Chuck Hoysa, Past Extension Agent and Soil & Water.
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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
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.
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.
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