Trees D iseases 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

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 Disease PathogenSusceptible 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 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

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: Colletotrichum Kabetiella Phyllosticta Gloeosporium Discula many 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 blooms Bacterial ooze may be visible Blighted leaves stay attached Forms shepard’s crook

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.

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

Spores are dispersed throughout the summer, but infection periods are unknown Hosts include : Oriental arborvitae Baldcypress Arizona cypress Italian cypress Leyland cypress Junipers Dieback is from the inside out

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

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

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

Black Knot Common gall on cherries, plums, and peaches. Symptoms include dieback of branches, thin crowns, and gnarly black galls on trunk or branches. Control: Prune branch galls six to eight inches below infection. It is impractical to remove trunk galls.

Wetwood and Slimeflux Caused by bacteria. Hosts: Oaks Popular Elms Other symptoms: fermentation smell, swarming insects

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.

Wood Decay Fungi Ganoderma Inonotus Hypoxylon Hispidus Canker Irpex Canker

Hypoxylon Canker

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.

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!

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

Hispidus Canker Primarily found on oak species Once trunk decay fungi are actively growing, there is no control. Improve tree vigor to add to its lifespan!

Vascular Wilts Diseases that interfere with the uptake and flow of water and nutrients.

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.

Dutch Elm Disease DED Yellowing, 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 Rot PrimaryHosts: Cedar Hemlock Pines Symptoms include general tree 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 powdery mildew on Hackberry tree.

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

Mature gall Actively sporulating galls

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

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.

Trees Pests Developed by: Leslie Paulson, 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 & 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?