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Yard Tree Health FAQ

The tree I planted has always done poorly.

Diagnosis:  In the absence of more definitive symptoms, a prime suspect is that the tree is planted in a place that doesn’t suit it.  Sometimes a species will thrive in one part of the yard and be stunted or die in another part of the same yard.  This is especially true where soil has been pushed from one area to another, compacted and mixed with construction debris.  Often the texture, acidity/alkalinity and soil moisture are not suitable.  Many species do not thrive in the shade of larger trees.  Also, trees may not thrive outside their native climatic range.  Planting trees in a spot to which they are poorly suited decreases tree growth and vigor and sets the stage for insect and disease problems.  Another possible reason for poor performance is that the tree was not planted right.

The leaves of my tree/shrub are yellowish.

Diagnosis:  Possibly a deficiency of nitrogen, sulfur, or iron.  If all the leaves are entirely yellow including the veins, it is probably a sulfur deficiency.  If only the veins are green, it is probably an iron deficiency.  If the yellowing is more pronounced on the older leaves, it is likely a nitrogen deficiency.

Treatment:  A good first step is to have the soil tested by the UT Extension Service.  Adding ammonium sulfate can treat both nitrogen and sulfur deficiency.  Iron deficiency can be treated by adding an iron chelate and by acidifying the soil.  Since adding ammonium sulfate acidifies the soil, adding it with an iron chelate will treat all three deficiencies at once.

My white pine (5 needles per bundle) is oozing white resin and is turning brown from the ground up.

Diagnosis: If the oozing occurs in the lower three feet of the trunk, it may be Procerum root rot.  (Note: white resin alone does not mean your tree has this pathogen.)  Root rot of white pine is most common on poorly drained and clayey soils.  These conditions are especially common in Middle Tennessee and in the valleys of East Tennessee.  The disease most commonly strikes white pines 5 years and older.

Treatment: Remove diseased trees to help prevent spread to healthy trees; treat stumps with permethrin to prevent spread by weevils, or remove stumps.  Do not replace with another white pine.

Note: White pine in the above-described conditions suffers more pest problems than it does in its native range (it prefers cool, moist, well drained sites).  Even in the absence of root rot or other pests, it is common for white pine planted on sites to which it is poorly suited to grow well for 20 years or so and then die of no apparent reason. 

My white pine’s inner needles are turning yellow in the fall, then brown, and then falling off.

Diagnosis:  Natural needle drop (so long as this year’s needles stay on the tree.)

My maple tree is losing a lot of leaves this spring; the swollen bases of the leaf stems have little holes in them.

Diagnosis: Maple petiole leaf borer.  This will not hurt the tree, and no treatment is necessary.

The outer twigs on my oak didn’t leaf out; the leaves are clustered toward the middle of the tree (some of the current year’s leaves turn red in late summer and remain on the tree.)

Diagnosis: Oak decline.  This problem arises from stresses to the tree, specifically drought, root damage from soil compaction or digging, severe or repeated defoliation by insects or hard late spring freezes, shallow soils, shoestring fungus, borers, slope, aspect and old age.  Decline persists for several years and often leads to mortality.

Treatment:  Mulch out to drip line, water during droughts, and fertilize.  This can be effective if the condition is not far advanced and if the tree is not too old.  Trees with more than one-third dieback will not recover and will continue to die back after further stresses.

The leaves of my maple dropped early this fall.  The leaves were the normal size with fall colors but the crown was less full than normal (there may be twig or branch death on older trees.  These trees also may leaf out later in the spring with fewer live branches with leaves on them.  Over several years the tree becomes stag headed with dead branches.) 

Diagnosis:  Maple decline.

Treatment:  Same as for oak decline (see above.)

The leaves on my oak tree suddenly wilted; the leaves drop off the tree while still green or tan/green in color in the month of June.

Diagnosis: Oak wilt.  This disease is caused by a fungus that clogs the water conducting structures in the wood.  Always fatal.

Treatment: Remove dead tree.  Do not wound healthy trees nearby, and prune them only in winter when sap-feeding insects do not spread the disease.  Trench between dead tree and other susceptible oaks close by to break root contact.

My maple is wilting (or is turning yellow) branch by branch (or up to one-half of the tree may die suddenly; often remaining leaves are under-sized and yellow-green; twig growth reduced to less than one inch.)    If I cut off a branch, there is a ring of spots or discolored olive-green sapwood in the cross section.

Diagnosis: Verticillium wilt, caused by a fungus.  Verticillium occasionally affects other species such a sassafras and elm.

Treatment:  Most successful if caught early.  Some mildly affected trees may recover without treatment.   If symptoms affect entire tree, it will probably die.   Fertilize with ammonium sulfate fertilizer at a rate of 1.6 lbs (3/4 of a one-pound coffee can full) per 100 square feet of ground surface under the tree.  Start two feet out from trunk and end ten feet beyond the ends of branches.  Water if dry (but don’t over-water.) 

The leaves of my tree (specifically pin oak, elm, maple, sycamore, mulberry) are turning brown along the margins.  Dead upper branches occur with leaf drop.

Diagnosis: Bacterial leaf scorch. Appears in late July or early August on individual branches.  As the disease progresses, scorch symptoms appear on all the leaves. In subsequent years infected trees decline and foliage may be sparse and limited to branches in the interior of the tree’s canopy.  Severe dieback and decline precede death of the entire tree in three to four years.

Treatment:  Tree death is common with this disease. Improving tree vigor may help trees showing mild scorch symptoms.  Irrigation when moisture is limited may extend the life of the tree.  Low volume injections of oxytetracycline on oak and elm have produced a remission of symptoms but no cure.  Contact an arborist who is ISA (International Society of Arboriculture) certified.  Trees in the severe stages of decline should be removed.

This spring the leaves of my tree (dogwood, ash, maple, sycamore or walnut) had brown blotches (patches) often bounded by leaf veins, which then wilt and fall off the tree (sycamores especially can have twig dieback.)

Diagnosis:  Probably a fungal disease called anthracnose.  (Weather-related, especially prevalent during wet cool springs (70s and below) during leaf development.  Dogwood anthracnose is worse at elevations above 1000 feet and on moist humid sites.)

Treatment:  Remove infected limbs as soon as symptoms are detected.  Rake and destroy or thoroughly compost leaves. 

My tree puts on healthy leaves in the spring, but as the weather gets warmer, they get stunted and crinkly, with browning of the leaf margins.

Diagnosis: The problem is probably heat and drought, possibly combined with a soil type that is poorly suited to the species of tree.

Treatment:  Mulch around the tree three to four inches deep in a bowl and water during dry periods.  If the problem persists year after year, consider planting a more drought-tolerant species.

The base of my tree is decayed.

Treatment:  The best thing to do is leave it alone.  Cleaning out the decay will only make things worse.  The tree will create rings of decay-resistant wood around the decay that will stop its spread.  Cleaning out the decay risks breaking through that layer.  Painting the wound is ineffective and may inhibit the growth of callous tissue around the wound.  Filling the hole with concrete is also ineffective in stopping decay, but may block wood-eating insects from entering the tree. 

My pine turned brown, and there are little globs of white or reddish-brown pitch on the trunk.

Diagnosis: Pine beetles, either Southern pine beetle or ips engraver beetle.  Look also for pinhead-sized exit holes. These beetles attack loblolly, shortleaf and Virginia pines.

Treatment:  Remove dead tree and surrounding pines to prevent spread.  Permethrin can be sprayed on the lower two-thirds of valuable trees on all sides to the point that it begins to run off.

My cedar trees have strange-looking gelatinous orange swellings on the branches.

Diagnosis:  Cedar-apple rust.

Treatment:  None needed.  Cedar-apple rust lives on apple leaves in another phase of its life cycle, where it may cause significant defoliation.  Remove swellings if objectionable; galls take two or three years to develop again.

There are tough oblong bags about an inch or two long hanging from my bushes.  The foliage is gone from some of the branches.

Diagnosis: Bagworms.  They affect many species but are most commonly seen on cedar and arborvitae.  Can cause severe and repeated defoliation.

Treatment:  Remove and destroy bags.  Spray bags on bush with insecticide if they are still small.  Spraying is most effective in May with cyfluthrin or fluvalinate.

There are horizontal lines of little holes in the bark with sap flow streaming from holes, especially in early spring.

Diagnosis: Yellow-bellied sapsucker, a type of woodpecker.  Holes are usually harmless, but can sometimes introduce fungus into tree trunk or girdle smaller branches with repeated pecking on the same trees. 

Treatment: Tie plastic window screening over affected area.

Caterpillars are eating the leaves off my tree this spring.

Diagnosis: Caterpillars of various species, including eastern tent caterpillar, forest tent caterpillar, spring or fall cankerworm, variable oak leaf caterpillar, and various species of inchworms.

Treatment: None needed for the health of the tree.  Native caterpillar infestations follow a natural cycle – they reach high levels and then virtually disappear the next few years.  Defoliation will not significantly hurt healthy trees, although when heavy defoliation (greater than 50% of leaves removed) occurs, weakened trees are predisposed to other pests which can lead to tree death.  Keep the tree mulched and watered.  Mulch should not be more than four inches deep and should not be piled around the tree trunk.  Unsightly tent caterpillars, which most commonly attack black cherry, can be killed by spraying the tree with insecticidal soap, cyfluthrin or horticultural oil when the leaves are half emerged, or the webbing can be physically removed.

Long green insects are eating the leaves off my tree.

Diagnosis: Walkingsticks.

Treatment: None necessary (see above under “caterpillars”).

The leaves of my oaks have round balls on them and they are falling of the tree; the twigs have swellings that look like marshmallows.

Diagnosis: Gall wasps.

Treatment:  None needed.  Pruning can be done on branches of trees that have repeated attacks.

There are red and black bugs all over my boxelder tree.

Diagnosis:  Boxelder bugs.

Treatment:  None needed, but if desired for aesthetic reasons, treat congregated bugs with permethrin, bifenthrin, or cyfluthrin.  Rake areas around trees and house foundations free of leaves, seeds and other areas favored for egg laying and living.

There are holes scattered over the trunk of my tree

Diagnosis:  Borers.  The flatheaded apple borer and the dogwood borer are the most common.

Treatment:  Flatheaded apple borer (also attacks dogwood): spray trunk and branches with permethrin in mid-May and late June.  Dogwood borer: spray trunk and branches with permethrin in late April and early July.  See Commercial Insect and Mite Control, PB 1589; see also Common Tree Borers in Tennessee, ST 547 these and other publications can be found in the publication section of the UT website at