Diseases and Insect Pests of Hardwoods (Broadleaf trees) – by species

Apple/Crabapple (Malus):
Aphids on Deciduous Trees and Shrubs
Apple Maggot Management
Apple Scab
Disease Management Recommendations for Trees and Shrubs
(Black Rot Canker, Cedar-Apple Rust, Fireblight, Frog-eye Leaf Spot, Powdery Mildew, and Apple Scab)
Fireblight
Forest Tent Caterpillars in Minnesota
Forest Tent Caterpillar (USFS)
Gypsy Moth (USFS)
Gypsy Moth in Minnesota (MNDNR)
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Scale Insects of Trees and Shrubs
Spring and Fall Cankerworms
Woolly Aphids on Trees and Shrubs

Ash (Fraxinus):
Anthracnose Diseases of Eastern Hardwoods
Anthracnose of Ash Trees
Anthracnose of Shade Trees
Aphids on Deciduous Trees and Shrubs
Ash and Honeylocust Plant Bugs
Ash Flower Gall
Ash Plant Bugs
Ash Rust
Three Ash Diseases You Should Know (MN DNR)
HOW to Identify and Manage Ash Yellows in Forest Stands and Home Landscapes (USFS)
Disease Management Recommendations for Trees and Shrubs (Anthracnose, Ash Yellows, Heart Rot, Sulfur Shelf Heart Rot, Verticillium Wilt)
Emerald ash borer
Forest Tent Caterpillars in Minnesota
Forest Tent Caterpillar (USFS)
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Nectria Canker
Sawflies of Trees and Shrubs
Scale Insects of Trees and Shrubs
Spring and Fall Cankerworms
Verticillium Wilt of Trees and Shrubs
Woolly Aphids on Trees and Shrubs

Aspen/Cottonwoods/Poplar (Populus):
Decay and Discoloration of Aspen (USFS)
Disease Management Recommendations for Trees and Shrubs
(Cankers, Leaf Rust, Marssonina Leaf Spot, and Shoot Blight)
Forest Tent Caterpillars in Minnesota
Forest Tent Caterpillar (USFS)
The Gypsy Moth (USFS)
Gypsy Moth in Minnesota
Hypoxylon Canker of Aspen (USFS)
Hypoxylon Canker on Aspens and Willows
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Leaf Beetles in Urban Landscapes
Leaf Spot Diseases of Poplar
Nectria Canker
Scale Insects of Trees and Shrubs
Spear-Marked Black Moth (USFS)
HOW to Identify and Minimize White Trunk Rot in Aspen (USFS)

Basswood/Linden (Tilia):
Anthracnose Diseases of Eastern Hardwoods
HOW to Identify Introduced Basswood Thrips (USFS)
Forest Tent Caterpillars in Minnesota
Forest Tent Caterpillar (USFS)
The Gypsy Moth (USFS)
Gypsy Moth in Minnesota
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Japanese Beetle Management in Minnesota
Lace Bugs on Deciduous Trees and Shrubs
Nectria Canker
Sooty Mold
Spring and Fall Cankerworms

Beech (Fagus):
Beech Bark Disease (USFS)

Birch (Betula):
Anthracnose Diseases of Eastern Hardwoods
Birch Dieback
Birch Leafminers
Birch FAQ’s
The Bronze Birch Borer (USFS)
The Bronze Birch Borer and Its Management
Forest Tent Caterpillars in Minnesota
Forest Tent Caterpillar (USFS)
The Gypsy Moth (USFS)
Gypsy Moth in Minnesota
MDA Gypsy Moth program
HOW to Grow and Maintain a Healthy Birch Tree (USFS)
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Nectria Canker
Sawflies of Trees and Shrubs
Spear-Marked Black Moth (USFS)

Black Locust (Robinia):
The Locust Borer (USFS)

Catalpa (Catalpa):
Anthracnose Diseases of Eastern Hardwoods
Disease Management Recommendations for Trees and Shrubs
(Verticillium Wilt)
Verticillium Wilt of Trees and Shrubs

Cherry (Prunus):
Black Knot
Black Knot of Cherry
Disease Management Recommendations for Trees and Shrubs
(Bacterial Spot and Canker, Black Knot, Brown Rot, Canker, Leaf Spot, Plum Pockets and Leaf Curl, and Western X Disease)
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Lace Bugs on Deciduous Trees and Shrubs
Woolly Aphids on Trees and Shrubs

Cottonwoods (Populus)- See Aspen

Dogwood (Cornus):
Disease Management Recommendations for Trees and Shrubs
(Leaf Spot)
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects

Elm (Ulmus):
Anthracnose Diseases of Eastern Hardwoods
Disease Management Recommendations for Trees and Shrubs
(Cankers, Dutch Elm Disease, Elm Black Leaf Spot- elm anthracnose, Oyster canker, and Wetwood or Slime Flux)
Dutch Elm Disease
History of Dutch Elm Diseases in Minnesota
HOW to Differentiate Dutch Elm Disease From Elm Phloem Necrosis (USFS)
HOW to Identify and Manage Dutch Elm Disease (USFS)
HOW TO Save Dutch Elm Diseased Trees by Pruning (USFS)
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Leaf Beetles in Urban Landscapes
Nectria Canker
Scale Insects of Trees and Shrubs
Sooty Mold
Spring and Fall Cankerworms
Trees Weeping Along Bark
Woolly Aphids on Trees and Shrubs

Hackberry (Celtis):
Disease Management Recommendations for Trees and Shrubs
(Witches Broom Fungus)
Spring and Fall Cankerworms
Hackberry Nipple Gall
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Lace Bugs on Deciduous Trees and Shrubs

Hawthorn (Crataegus):
Disease Management Recommendations for Trees and Shrubs
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Lace Bugs on Deciduous Trees and Shrubs
Woolly Aphids on Trees and Shrubs

Hickory (Carya):
Anthracnose Diseases of Eastern Hardwoods
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Phomopsis Canker and Gall

Honeylocust (Gelditsia):
Ash and Honeylocust Plant Bugs
Disease Management Recommendations for Trees and Shrubs
(Nectria Canker)
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Nectria Canker

Horsechestnut/Ohio Buckeye (Aesculus):
Anthracnose Diseases of Eastern Hardwoods
Disease Management Recommendations for Trees and Shrubs
(Leaf Blight)
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects

Lilac (Syringa):
Bacterial Blight of Lilac
Disease Management Recommendations for Trees and Shrubs
(Bacterial Blight, Powdery Mildew)
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Scale Insects of Trees and Shrubs

Maple (Acer):
Anthracnose and Other Fungal Leaf Spot Diseases of Maple
Anthracnose Diseases of Eastern Hardwoods
Anthracnose of Shade Trees
Aphids on Deciduous Trees and Shrubs
HOW to Identify and Control the Sugar Maple Borer (USFS)
Cottony Maple Scale
Disease Management Recommendations for Trees and Shrubs
(Anthracnose, Leaf Spot, Target-Shaped Canker, Tar Spot, and Verticillium Wilt)
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Maple Petiole Borer / Maple Trees Dropping Leaves
Maple Leaf Galls
Nectria Canker
HOW to Control Sapstreak Disease of Sugar Maple (USFS)
Scale Insects of Trees and Shrubs
Spring and Fall Cankerworms
Verticillium Wilt of Trees and Shrubs
Woolly Aphids on Trees and Shrubs

Mountain-Ash (Sorbus):
Disease Management Recommendations for Trees and Shrubs
(Black Rot, Cankers)
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Sawflies of Trees and Shrubs
Scale Insects of Trees and Shrubs

Oak (Quercus):
Anthracnose Diseases of Eastern Hardwoods
Oak Anthracnose
Aphids on Deciduous Trees and Shrubs
Oak Decline (USFS)
Bur Oak Blight
Disease Management Recommendations for Trees and Shrubs
(Anthracnose, Armillaria Root Rot, Oak Heart Rot, Oak Leaf Blister, Oak Wilt, and Smooth Patch)
Forest Tent Caterpillars in Minnesota
Forest Tent Caterpillar (USFS)
The Gypsy Moth (USFS)
Gypsy in to Minnesota
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Lace Bugs on Deciduous Trees and Shrubs
HOW to Distinguish Oak Leaftiers From Leafrollers (USFS)
Nectria Canker
Red Oak Borer (USFS)
Two-lined Chestnut Borer (USFS)
Two-lined Chestnut Borer-Management Options (USFS)
Smooth Patch
Spring and Fall Cankerworms
Oak Wilt (USFS)
Oak Wilt in Minnesota
HOW to Collect Field Samples and Identify the Oak Wilt Fungus in the Laboratory (USFS)
HOW to Identify, Prevent, and Control Oak Wilt (116 KB) (USFS)
Protecting Your Trees From Oak Wilt

Ohio Buckeye (See Horsechestnut)

Poplar (See Aspen)

Walnut/ Butternut (Juglans):
Anthracnose Diseases of Eastern Hardwoods
HOW to Identify Butternut Canker and Manage Butternut Trees (USFS)
HOW to Diagnose Black Walnut Damage (USFS)
Disease Management Recommendations for Trees and Shrubs
(Anthracnose)
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Lace Bugs on Deciduous Trees and Shrubs
HOW to Identify and Control Leaf Spot Diseases of Black Walnut (USFS)
HOW to Identify and Control Black Walnut Mycosphaerella Leaf Spot (USFS)
Nectria Canker

Willow (Salix):
Aphids on Deciduous Trees and Shrubs
Disease Management Recommendations for Trees and Shrubs
(Cytospora Canker,Willow Scab/Twig Blight)
The Gypsy Moth (USFS)
Gypsy Moth in Minnesota
Hypoxylon Canker on Aspens and Willows
Insecticide Suggestions to Manage Landscape Tree and Shrub Insects
Lace Bugs on Deciduous Trees and Shrubs
Sawflies of Trees and Shrubs
Scale Insects of Trees and Shrubs

MyMinnesotaWoods
The University of Minnesota Extension Forestry team.

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4 Comments

  1. We have a boxwood tree that stands separate from our other trees on our lake property. over the last year we have noticed dead branches here and there. Just a few weeks ago we noticed a soft spot at the base of the trunk next to the ground. We pushed on it and our fist went thorugh. Out came decayed wood (almost sandlike) and white worms the size of quarters. any advice? Is our beloved shade tree too far gone to be helped? Is there anything we can do to stop the progress of what appears to be a slow death?

    1. Hi Karen. I hate to be the bearer of bad news, but when decay is that advanced in a tree, there’s really nothing that can be done to save it. If the tree is in an area where it could pose a hazard if it were to fall, I would recommend that you remove the tree soon, as it sounds like the decay is rather advanced.

      I’m not familiar with boxwood. Did you mean boxelder? If so, that’s one of the trees least able to compartmentalize and grow through decay and wounds. In other words, most likely to have serious structural damage after a wound. If you’re not sure about the species, the Minnesota Trees guide may help. But again, sadly there’s not a lot that can be done for this tree from the way you describe it, whatever the species.
      -eli

  2. Thanks Susan for the suggestion. I just fixed a few bad links in the oak section. Do you have other suggestions in mind to improve that section?