What's wrong with my plant? : Garden : University of Minnesota Extension

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Leaves in upper canopy look wilted, turn brown but remain attached to branch for several weeks
1/8 inch D-shaped exit holes
S-shaped galleries underneath bark
Bluish black bodies with two light stripes running down the wing covers
Larvae are approx. 1 inch long and white with 2 spines at abdomen tip
Damage visible mid to late summer
More information on twolined chestnut borer

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Infected trees have poor growth, dead branches in the upper canopy, undersized and/or yellow leaves
Flat white sheets of fungal mycelia (mycelia fans) grow between the bark and sapwood at the base of infected trees
Thick black, shoestring-like fungus can sometimes be seen under the bark, around roots and in the soil around the base of the tree
Wood is decayed, white, soft and spongy, and this may extend from the base of the tree well up into the trunk
Trees frequently break or fall over in storms
Clusters of honey-colored mushrooms may grow at the base of the tree in fall
Twolined chestnut borers often found on trees affected by Armillaria root rot
More information on Armillaria root rot

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Affected trees commonly exhibit excessive and abnormal winter damage including frost cracks and dieback
A root circling the trunk of the tree may be seen at the soil line
Trunk may be sunken in or compressed where it contacts the root
If girdling root is below ground, the trunk will lack the natural widening or flare at the soil line so will go straight into the earth like a telephone pole; trees often exhibit an abnormal lean
Affected trees are often stunted, exhibit poor summer color, change color and lose their leaves early in the fall
Affected trees commonly exhibit water-stress symptoms such as marginal leaf scorch, wilting, sudden leaf fall
More information on Stem girdling roots

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Continuous, sporadic or twisting, vertical stripping from bark torn away on main stem or other large branches
Cracks or splits in bark from lightning strikes begin in the canopy and extend to the ground line
Often, large pieces of wood strewn about the hit tree
Death more common on trees within red oak group; strikes more common when oaks are tallest in area
More information on Lightning injury

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Leaves are smaller in size and turn yellow earlier than normal
Canopy appears thin with few leaves and multiple dead branches
Fungal conks, a semicircle shelf fungi, can be found from the base of the tree up to 3 feet high on the trunk
Conks are reddish brown and shiny on top, white and porous underneath, a rim of white may be visible on the edge of growing conks
Infected wood at the base of the tree is white, soft, stringy or spongy
Infected trees frequently break or fall over in storms
More information on Ganoderma butt rot

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The canopy may show no symptoms or may have small yellowing leaves or dead branches depending on the extent of the trunk decay
In cross section of the trunk, the wood at the center is discolored, soft, crumbling, stringy or spongy
Fungal fruiting bodies arise along the stem, near a pruning wound, crack or other wound
Many shapes and sizes of fungal fruiting bodies may be seen
Phellinus spp. have hoof shaped fruiting bodies that are black on top and yellow brown underneath
Laetiporus sp. have folds of yellow to bright orange fungal tissue arising in a clump
More information on heart rot

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Soil salt damage causes leaf edges or margins to appear burnt or scorched progressing toward the mid-vein
Soil salt damage can mimic nutrient deficiencies, e.g., yellowing foliage on deciduous plants
Salt spray causes branches to become tuft-like (a.k.a. witches’ broom)
Run-off salt kills roots which results in die-back of most branches
Affected trees leaf out later than other non-infected trees
All deicing damage most noticeable in spring
More information on Deicing salt injury

Oak > Trunk/Branches > Dead branches or branch dieback