Diagnosing Health Problems of Woody Plants at the Shade Tree Short Course 2022

Below are the common problems PIDC diagnosed in 2021 that were showcased in the hands-on workshop Diagnosing Health Problems of Woody Plants at the Shade Tree Short Course 2022.

See our glossary page to learn the term used to describe symptoms and signs.

 

Station No 1.

Tree(s): oaks

Symptoms observed: brown tips on branches spread out from the bottom of the tree canopy upwards.

Signs present (visible)? (Y/N): not visible with the naked eye, magnification needed

Nature of the problem: disease

Diagnosis: Botryosphaeria Twig Canker management

Resources Oak Wilt or Bot Twig Canker?Cankers and Diebacks With One Common Suspect: Botryosphaeria

 

Station No 2.

Tree(s) Maple (silver, Norway, etc.)

Symptoms observed: spots, different sizes, little spots that appear to merge to form large ones.

Signs present (visible)? (Y/N), No, not visible with the naked eye, magnification needed

Nature of the problem: Disease

Diagnosis: Tar spot

Resources Maple Tar SpotOccurrence of European Tar Spot (Rhytisma acerinum) on Norway Maple (Acer platanoides) Causing Severe Infections in Minnesota

 

Station No 3.

Tree(s): Various Bur, red, white oaks are hosts

Symptoms observed: Tufts of dead leaves,  Terminal bud damage – slower growth, bushier.

Signs present (visible)? (Y/N) Yes

Nature of the problem: Insect

Diagnosis: Kermes scale damage

Resources Scale Insects

 

Station No 4.

Tree(s): Common on lilac, ash, dogwood, maple,  poplar, and willow, but reported on more than 130 host plants.

Symptoms observed Twig and branch dieback, early fall color on maples, leaves held on branches in fall, often worse on young trees.

Signs present (visible)? (Y/N) Y

Nature of the problem: Insect

Diagnosis: Oystershell scale damage

Resources Oystershell scaleScale Insects

 

Station No 5.

Tree(s): Maple, many young and old trees

Symptoms observed: dieback

Signs present (visible)? (Y/N) N

Nature of the problem: Abiotic

Diagnosis: Planting problems

Resources: Why is my newly planted tree dying?Tree and shrub care

 

Station No 6.

Tree(s): evergreens

Symptoms observed: south-facing color change of needles (browning

Signs present (visible)? (Y/N): N

Nature of the problem: Abiotic

Diagnosis: Winter desiccation

Resources Winter Desiccation Injury to ConifersProtecting Trees and Shrubs in Winter

 

Station No 7.

Tree(s): crabapple (Malus toringo Siebold's) and Juniper (especially Juniperus chinensis L. var. kaizuka Hollywood juniper)

Symptoms observed” galls in junipers, aerial tubes in crabapple leaves

Signs present (visible)? (Y/N), Y

Nature of the problem: Disease

Diagnosis: invasive Japanese apple rust Gymnosporangium yamadae, not reported in IA, if supect contact the Plant & Insect Diagnostic Clinic

Resources

Yun, H.Y. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Invasive Fungi. Japanese apple rust. Retrieved January 26, 2022, from /sbmlweb/fungi/index.cfm 

https://www.cabi.org/isc/datasheet/26238

https://www.plantwise.org/knowledgebank/datasheet/26238#DistributionSection

 

Station No 8.

Tree(s): Lilac, Ash, elms, may more hosts

Symptoms observed: witches broom and tissue proliferation, leaf yellowing

Signs present (visible)? (Y/N) N, specialized testing needed, Plant & Insect Diagnostic Clinic has available DNA testing for suspect plants.

Nature of the problem: Disease

Diagnosis: Aster yellow, Phytoplasma diseases

Resources Aster YellowsAsh Decline.; Chapter 37 Common Disease of the Great Plains

 

Station No 9.

Tree(s): Norevergreen, many other species

Symptoms observed: burn, discolored tissue distortion.

Signs present (visible)? (Y/N): N

Nature of the problem: Abiotic

Diagnosis: Herbicide damage injury

Resources Understanding and preventing herbicide injury

 

Station No 10. unknown mistery

 

Station No 11.

Tree(s) maples. others

Symptoms observed:  cut offshoots, trunk wounds

Signs present (visible)? (Y/N) No

Nature of the problem: Animal damage

Diagnosis: Squirrel damage

Resources Squirrel Damage on Trees and Shrubs

 

Station No 12.

Tree(s) Wide host range, but oak, elm, and ash are common

Symptoms observed

Signs present (visible)? (Y/N) Y, Signs include sap drip darkening bark, course sawdust-like frass, hole larger than a pencil, empty pupal casing

Nature of the problem: insect

Diagnosis: Carpenterworm

Resources Be Aware of the Carpenterworm

 

Station No 13.

Tree(s) linden, basswood, poplar

Symptoms observed: Bark bulges out and cracks where they feed exit holes

Signs present (visible)? (Y/N): potentially

Nature of the problem: Insect

Diagnosis: linden borer

Resources Linden borer 

 

Station No 14.

Tree(s): Austrian, Scott’s pine

Symptoms observed: brown short new needles (tips), browning spread out from the bottom of the tree canopy upwards.

Signs present (visible)? (Y/N) Yes, in pine cones, microscopic fungal cones often need magnification

Nature of the problem: disease

Diagnosis: Diplodia tip blight and canker

Resources Diplodia Tip Blight and Canker

 

Station No 15.

Tree(s)/shrubs: Lilac

Symptoms observed: leaf spots, blight during the summer months

Signs present (visible)? (Y/N) Yes, observed under magnification

Nature of the problem: Disease

Diagnosis: Lilac foliar diseases

Resources Summer Foliar Lilac Diseases

 

Last Reviewed: 
February, 2022

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