1. Trees Pests and Diseases
Developed by:
Janet Anastasi, Master Gardener Volunteer
Frank Reilly, Advanced Master Gardener & Tree Steward
Leslie Paulson, Advanced Master Gardener & Tree Steward
With input from
Page Thacker, Unit Coordinator & Extension Agent
And the
Prince William County Tree Team

2. Trees Pests and Diseases Environmental and other Non-Living Factors
Developed by:
Janet Anastasi, 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

3. Environmental Factors

4. Why Plant a Tree? Provide shade Provide aesthetics in the landscape
Improve air quality
Reduce storm-water runoff and improve water quality
Create wildlife habitat
Reduce noise levels
Provide screening and privacy
The first question to ask when selecting a tree is “What is the purpose of the tree being planted?” There are a variety of reasons to plant a tree in urban environments. These reasons include to cool the environment by providing shade. Another is to add an aesthetic quality to the landscape through leaf color or texture, flowers, fruits and bark colors and textures. Trees can improve air quality by acting as filters and scrubbers in removing some particulate matter from the air. They can help with water quality by assisting in slowing down soil erosion and absorbing storm water and helping filter out pollutants. Trees can provide a habitat for birds, squirrels, and other wildlife in an urban environment. Trees can serve as a noise buffer to help reduce noise from this such as traffic. Also tree can act as a screen to block a unpleasant view or just to provide privacy.

5. Tree Roots – where they are?

6. TYPES OF CONSTRUCTION DAMAGE
Environmental Changes
Soil compaction
Excessive thinning
Moisture stress
Soil fill
Soil cuts

7. Soil Compaction Causes: Running of heavy equipment over root zones
Piling of debris on top of tree roots
Parking under a tree

8. Soil Contamination
Prevent soil contamination that can damage or kill trees!
Watch out for fuel leaks.
Do not allow on-site paint dumping.
Plan for cement or mortar wash out areas.
Is this a good home building site?

9. Site Factors Light patterns Temperature extremes Precipitation
Environmental Conditions
Light patterns
Temperature extremes
Precipitation
Wind patterns
Air quality
To ensure that tree will grow to maturity in good health it is important to evaluate the environmental conditions at the site. Environmental condition to consider are:
Light patterns: Consider the amount of sunlight, shade and artificial light at the site, including the duration and directness of sunlight. Questions to ask at the site are: How often is the tree in full sun or shade? Are there buildings or other trees shading the site? Are there artificial lights shining on the tree all night? Is there reflective light from buildings, streets and other structures? Light patterns can even change the dormancy and growth patterns of the tree. Visiting the site at different times of the day and season will help determine the light patterns and help in choosing a species appropriate to those conditions.
Temperature extremes: It is important to know if a species can survive the temperature extremes at the planting site. The average minimum temperature can be determined from hardiness zone maps. Urban areas are usually warmer than rural ones because of the “heat island” effect, but site specific factors can cause even greater extremes. For example, tree planted next to a black asphalt road will have much hotter conditions and will probably require more water than those planted in a park or yard. Some sites are subject to early and late frosts, such as ridge tops, large open spaces, low areas and frost pockets.
Precipitation patterns: Precipitation patterns directly influence site conditions. How much rainfall does the site typically receive? When are the dry months? Select species adapted to the precipitation patterns of the site.
Wind patterns: Strong winds may blow down trees and snap trunks and limbs. Constant wind increases the trees need for water because of increased transpiration. Buildings in downtown areas can create a wind-tunnel effect and increase wind speed in those locations. Are wind storms, tornadoes and hurricanes common in the area? Sites expose to strong winds should have adequate soil volume for good root development and the tree species should have a structure and branch attachment that can tolerate windy conditions.
Air Quality: Air pollution may damage foliage and impair photosynthesis. Is the planting area near a major road with large quantities of exhaust fumes. Some species tolerate specific pollutants better than others.

10. Site Factors Texture Compaction Moisture & drainage Fertility and pH
Soil characteristics
Texture
Compaction
Moisture & drainage
Fertility and pH
Temperature
Contamination
Salt
Soil conditions are among the most critical considerations for tree growth and survival. Some of the soil characteristics to consider when selecting a site are:
Soil texture: Soil texture influences soil fertility and the way air and water move through the soil. Typically, heavy clay soils have poor aeration and drainage but good fertility; sandy soils have good drainage and aeration but poor water retention and fertility; and loamy soils have good aeration, drainage, water retention and fertility.
Soil compaction: This is a very important factor to consider for tree survival. Compacted soils are a leading cause in urban areas for tree decline. Compacted soils have poor soil structure, drainage and aeration.
Soil Moisture & drainage: Soil moisture is influenced by many factors, such as soil texture and structure, precipitation patterns, hardpan, and soil interfaces. High soil moisture conditions or poorly drained soils can be a leading cause to urban tree decline (depending on the species of tree).
Fertility and pH: Since leaves and other tree litter are usually raked and not left on the ground to decompose, the soil may lack necessary nutrients and fertility may be low. Construction activities, such as removal of topsoil and cement wash outs may also alter soil nutrient availability and pH conditions.
Soil temperature: The temperature of the soil influences root growth by controlling the rate of chemical and biological processes. Temperature extremes can freeze or dry out roots. If the site is in a paved area, such as a parking lot, or is in a container, soil temperatures may be higher than normal. Adding mulch to the planting area is one way to help maintain adequate soil temperature.
Contamination: Soil contamination may kill roots. Contamination can be caused by construction activities, chemical spills, excessive use of herbicides or other disturbances.
Salt: This can be a problem in costal areas. Salt greatly influences tree physiology because it binds with important nutrients the tree needs, thus prohibiting the tree from absorbing the nutrients. Salt also absorbs water in the soil that the tree needs. Selecting species tolerant to salt is usually recommended for those sites.

11. Non-Living Factors Nutrient Deficiency Water Stress Temperature Stress
Other

12. What is the Right Tree? Growth factors Soil requirements
Other Environmental requirements
Maintenance requirements
Another question to ask before planting a tree is what tree will best satisfy the reasons for planting it and be suitable for the site where it will be planted. In other words, plant the right tree in the right place. Many of the factors discussed about the site are also important ot consider when selecting a tree species. These factors include growth factors, soil requirements, other environmental characteristics ad maintenance requirements.

13. Right Tree Hardiness zone Wind and storm damage Light requirements
Other environmental factors
Hardiness zone
Wind and storm damage
Light requirements
Pollution tolerance
Insect and disease tolerance
Several environmental factors need to be considered when considereing selecting a tree species.
They include:
Hardiness zone: Tree species have different tolerances to both heat and cold. Knowing the hardiness for a species will help determine if it can survive at the planted site. You must know what hardiness zone you are planting in.
Wind and Storm Damage: For sites where wind and storm damage are a concern, a species with strong branching structure and wood strength should be chosen. Trees with a fast growth rate should be avoided. The tree species should also have a strong root system.
Light requirements: You need to consider the light requirements of the site to match the correct species. Sun loving trees need at least 6 hours of direct sun. Partial shade/sun trees need 3-6 hours of direct sunlight. Shade loving trees need less than 3 hours of direct sun or filtered sun.
Pollution tolerance: If the site is located where possible air quality problems are likely to occur a pollution tolerant species needs to be considered.
Insect and disease resistance: Insects and diseases should be considered in selecting a tree. The species selected should be resistant to those insects and diseases common to the area.

14. Tree Care after Construction
Aerate or use other soil alteration methods to re-introduce oxygen and reduce compaction.
Water deeply – to encourage new root development and reduce tree stress.
Inspect frequently – look for visible signs of insect or disease attack.
Mulch – them well but correctly!
Fertilize – in a year or two after they have recovered from construction stress.

15. Non-living and Cultural Factors
Can be tricky to diagnose
Good to know what is ‘normal’
Knowledge of past weather conditions
Knowledge of past cultural practices
Often referred to as disorders

16. Chlorosis Yellow leaves with green veins Indicates nutrient deficiency
Can be a fertilizer or pH problem
Can affect all trees -
pin oak - dogwood

17. Leaf Scorch Lack of water Common on newly planted trees
Can occur on established trees during drought
Common on trees with restricted roots

18. Winter Damage Timing is key
Late winter, early spring, before new growth emerges
Most common on broad leaf evergreens
Can show up as leaf scorch, dead branches

19. Herbicide Damage Knowledge of use
Distorted growth, especially at growing points
Most susceptible in spring as new growth emerges
Damage can be widespread

20. Needle Shedding Common on pines, especially white pine
Also occurs on other evergreens
Knowledge of plant is helpful
Look at other plants in neighborhood

21. 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

22. Conditions Necessary for Plant Disease
Pathogen
Susceptible Host
Telephone call to Cooperative Extension!
Favorable Environment

23. 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.

24. Diagnosis Accurately ID the plant – THE MOST important step!
Look for patterns of abnormalities

25. Diagnosis
Examine the site

26. Diagnosis
Look at the foliage

27. Diagnosis
Look at the trunk and branches

28. Diagnosis
Look at the roots and root collar

29. 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

30. 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

31. Insect Damage Leslie 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

32. You are “likely” to encounter.
Top 10 Diseases
You are “likely” to encounter.

33. 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

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

35. Primary causal agents:
Colletotrichum
Kabetiella
Phyllosticta
Gloeosporium
Discula
many more…..

36. Discula on Dogwood

37. Discula petal blight
Dieback caused by Discula

38. 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.

39. 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.
Septoria Leaf Spots are 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.

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

41. Sudden blighting, death of blooms Bacterial ooze may be visible
Symptomology:
Sudden blighting, death of blooms
Bacterial ooze may be visible
Blighted leaves stay attached
Forms shepard’s crook
Fire Blight – symptoms visible on the plant.

42. Fire Blight – life cycle

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

44. Cankers and Galls on trunks/branches - Seiridium Canker
Distinct, sunken lesions which lead to
dieback and death

45. Spores are dispersed throughout the summer, but infection periods
are unknown
Dieback is from the inside out
Hosts include :
Oriental arborvitae
Baldcypress
Arizona cypress
Italian cypress
Leyland cypress
Junipers
Seiridium Canker causes branches to die from the inside of the plant and progress towards the branch tips

46. Flattened cankers are associated with bleeding and resin.
Control:
Remove cankers in winter
Do not prune in May or June
Increase plant health
No chemicals available

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

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

49. Black Knot Common gall on cherries, plums, and peaches.
Symptoms include dieback of branches, thin
crowns, and gnarly black galls on trunk
or branches.
Black Knot Fungus or Black Knot Gall
No chemical control.
Control: Prune branch galls six to eight inches
below infection. It is impractical to remove trunk
galls.

50. Wetwood and Slimeflux Caused by bacteria. Hosts: Oaks Popular Elms
Wetwood/Slime Flux – are trunk and root flare oozing caused by bacterial infection.
Other symptoms:
fermentation smell, swarming insects

51. initiated through root and/or trunk wounds.
Wetwood or slime flux
bacterial infection
initiated through root and/or trunk wounds.
Oozing occurs when bacterial
pressure 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.
Wetwood – expensive attempts at control are not warranted

52. Wood Decay Fungi Ganoderma Inonotus Hypoxylon Hispidus Canker
Irpex Canker
Wood Decay Fungi – often attack weakened trees as secondary invaders. Pictured is the Hypoxylon fungus commonly found on declining oaks, beeches, etc. Infected trees should be removed. These types of cankers often kill the host trees within 3-8 years (or less) as the cankers girdle a tree’s trunk and open them up to breakage at these points of decay. Many of these fungi get initiated through branch or trunk wounds.

53. Hypoxylon - Attacking weakened trees like ones that have been damaged by drought, ice or lightning.
Hypoxylon Canker

54. Slighty sunken irregular areas on bark
Hypoxylon – symptoms
Symptomolgy:
Slighty sunken irregular areas on bark
Canker becomes blistered with clusters of perithecia
immersed in stromata causing the tree bark to exfoliate.
Colors vary from black, gray to tan.

55. Hypoxylon canker is most prevalent in
situations of weakened or stressed
hardwoods.
Hosts:
Oak
Beech
Hickory
Maples
Tupelo
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!
Hypoxylon – common hosts and control.
Controls are stop gap to slow the disease spread and try to increase tree longevity.

56. Hispidus Canker
Hispidus Canker - best control is to limit it from getting started by pruning off branch stubs, pruning correctly and by encouraging rapid wound closure.
Entry point for this fungus is usually through old branch stubs or wounds. Causes a soft, white heart rot.

57. Hispidus Canker Primarily found on oak species
Hispidus Canker – like other decay fungi once it gains entry into the wood of trunks or stems it is impossible to eliminate.
Once trunk decay fungi are actively growing, there is no control. Improve tree vigor to add to its lifespan!

58. Vascular Wilts Diseases that interfere with the
Vascular Wilts – Wilts are caused by fungi that attack trees and get into their vascular systems (xylem and phloem) blocking the movement of water and nutrients. Once this flow is blocked, trees wilt, yellow and die quickly.
Vascular Wilts
Diseases that interfere with the
uptake and flow of water
and nutrients.

59. Verticillium Wilt Sample Hosts: Maple, Ash, Elms, Magnolia, Redbud
Tulip 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.
Verticillium Wilt – a fungal disease that often gets into trees through damaged or declining root systems. Symptoms and common hosts are listed.

60. Yellowing, flagging and branch dieback
Dutch Elm Disease DED
Yellowing, flagging and
branch dieback
Staining under bark
Dutch Elm Disease (DED) is a vascular wilt caused by the fungus, Ceratocystis ulmi.
Symptoms are listed.

61. Prune infected branches and monitor insect vectors (elm bark beetles).
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.
Dutch Elm Disease – controls are listed but all should involve improving tree vigor.

62. Annosum Root Rot PrimaryHosts: Cedar Hemlock Pines
Symptoms include general
tree decline and wind-throw.
Annosum Root Rot – is a common conifer problem that attacks stumps and live trees.

63. 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

64. 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!

65. 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

66. Some Cool Ones to Know
How am I doing on time?

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

68. WITCHES BROOM – is a growth problem that results when terminal buds are damaged or destroyed and a bunch of lower buds are released. You get a whole bunch of weak shoots sprouting out that resembles a medusa head or a witches’ broom. What kills buds – disease, insects, frost, drought, etc.?
Witches’ Broom caused by powdery mildew on Witchhazel but there are many causes such as diseases, insects, frost, drought, etc.

69. Witches’ Broom caused by
mites and powdery
mildew on Hackberry tree.

70. Galls are abnormal growth responses
Cedar Apple Rust
Cedar Apple Rust is a fungus that attacks Southern Red Cedars and other junipers.
It does very little damage to the cedar but it does lots of damage to its alternate hosts which are apples and crabapples. So much damage, that old fruit orchard recommendations included clearing all cedars away from the nursery area.
Galls are abnormal growth responses
caused by fungi, insects, and bacteria

71. Actively sporulating galls Mature gall
Cedar Apple Rust – mature galls hang on the trees for years.
Young galls produce the long, orange colored horns and spores in the spring.
Actively sporulating
galls

72. Alternate host leaf spot. Most often seen on apples and crabapples.
Cedar Apple Rust – how it looks on apple and crabapple as leaf spots.
Alternate host leaf spot.
Most often seen on apples and
crabapples.

73. NEW DISEASES ON THE HORIZON Sudden 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.
New Diseases – Sudden Oak Death, SOD
Resources: Dr. Coder handouts, web site
Provides updates and background on the disease and its spread on the west coast.

74. Any Questions? http://advancedmastergardener.org/public.htm
The End
Any Questions?