University of Maryland Extension

FAQs - Trees Spring/Summer

redbud blooms

Eastern redbud photo: John Ruter, University of Georgia, Bugwood.org

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I live on a wooded lot and have many trees that are not looking so good. There are a couple that need to be removed and a few that look like they have a disease or are being eaten by some kind of bug. I also have a tree right next to my house that I’m not sure about keeping. Who should I contact about my trees?

Is it necessary to prune a Crape myrtle each year? I see them being pruned back hard every spring.

What is the greenish-brown fungus I see growing on the bark of many of the trees and shrubs on my property? Some of the trees look like they are declining and I was wondering if this fungus is the cause.

There is a white, foamy liquid oozing from a hole in the trunk of my willow oak about 4 feet from the ground. Ants and yellowjackets are attracted to it. Otherwise the tree looks healthy. Is this going to kill my tree?

Carpenter ants are crawling up and down the trunk of my maple tree and look like they are killing it. What should I do?

My very large oak tree has limbs that hang over portions of my roof. I am looking for information and guidance on pruning this tree. When is the best time to prune it and is okay to ‘top’ the tree?

I saw a vine growing up some mature trees that looked somewhat similar to English ivy but it had clusters of dark blue berries on it. The vine looked very dense and I assumed it was something invasive. Would you know what this vine was?

I have a weeping cherry tree that has some holes in the trunk. Sap is dripping out of them and is even dripping to the ground. So far the tree looks pretty healthy. Could this be some sort of insect infestation and what can I do to help the tree?

It is only August and the leaves of my dogwood tree are showing fall color. There are flowers planted underneath it which I water on a regular basis. I assume the tree has had enough water. Should I be concerned about my tree?

My neighbor’s tree is overhanging their fence and shading my vegetable garden. What can I do so that my garden can get more sunlight?

We have a row of Leyland cypress trees that are rapidly turning brown.  They look like the needles are being eaten by something.  I see these cocoons on the branches and was wondering if they have anything to do with the trees declining?

I live on a wooded lot and have many trees that are not looking so good. There are a couple that need to be removed and a few that look like they have a disease or are being eaten by some kind of bug. I also have a tree right next to my house that I’m not sure about keeping. Who should I contact about my trees?

In Maryland, all tree care professionals are legally required to be licensed by the MD of Natural Resources through the Licensed Tree Expert program. This licensure process ensures that the company and its employees are properly trained and educated in the profession of arboriculture and carry the appropriate amount of worker’s comp and business liability insurance. Always ask to see proof of licensure.

Many tree care companies hire certified arborists. This is a highly regarded credential in the tree care industry. Certified arborists are individuals who have passed a comprehensive examination developed by some of the nation’s leading experts on tree care. They are knowledgeable in all aspects of tree care. The certification program is administered by the International Society of Arboriculture.

In your case, since you are interested in evaluating tree health, diagnosing possible problems, and tree removal, you should consider contacting a certified arborist. You can find one in your area by looking on the above link. Since this sounds like a considerable job you should contact 2 or 3 companies to come out to give you an estimate.

Is it necessary to prune a Crape myrtle each year? I see them being pruned back hard every spring.

No, it is not necessary to (PDF) prune a crape myrtle. Ideally you should select the cultivar of tree that will fit the space. Crape myrtles come in many different sizes from shrubs to 20-30 ft. tall trees. Topping them destroys the natural growth habit of the plant. Pruning should be limited to removing suckers and damaged dead or crossing branches. Branch thinning or limbing them up can also be done to reveal more of their attractive peeling bark. To remove part of a branch, make a heading cut above an outward facing bud or cut back to another major stem. To remove an entire branch, make the cut just above the branch collar of the stem you are removing. Never make cuts flush to the trunk.  Pruning should be done in early spring before the new growth comes out.

What is the greenish-brown fungus I see growing on the bark of many of the trees and shrubs on my property. Some of the trees look like they are declining and I was wondering if this fungus is the cause.

You are describing lichens. Lichens are living organisms composed of a fungus and algae living in a symbiotic relationship. The algae derive nutrients through photosynthesis and therefore they do not take nutrients from the tree. Lichens colonize on tree trunks, branches, rocks and even fences. They themselves are not harmful to trees but do tend to grow on slowly growing plants. Your trees are declining for other reasons such as environmental stress, poor management, or being planted in the wrong location.

There is a white, foamy liquid oozing from a hole in the trunk of my willow oak about 4 feet from the ground. Ants and yellow jackets are attracted to it. Otherwise the tree looks healthy. Is this going to kill my tree?

This sounds like slime flux or wetwood. Symptoms are sap flowing from bark cracks or wounds in the trunk or branches. The liquid may smell fermented which then attracts insects. Slime flux is generally caused by common surface inhabiting bacteria or yeast fungi that invade wounds and live off the nutrients in the tree sap. The sap eventually is forced out of the wound by pressure from gases produced by the microorganisms living in the sap. No treatment will cure trees with slime flux symptoms. Keep the tree watered during dry periods and prune out dead wood. Fertilize, if necessary in late fall to ensure good vigor.

Carpenter ants are crawling up and down the trunk of my maple tree and look like they are killing it. What should I do?

Carpenter ants are not killing your tree but are a sign that your tree may have a serious problem. Carpenter ants are drawn to rotting wood and old decaying trees. Controlling the ants will not prolong the life of your tree.  The tree should be examined by a certified arborist for a diagnosis and treatment plan. If the tree is severely declining removal may be recommended.

My very large oak tree has limbs that hang over portions of my roof. I am looking for information and guidance on pruning this tree. When is the best time to prune it and is okay to ‘top’ the tree?

Topping trees is not a recommended pruning practice. The pruning cuts caused by topping are difficult for trees to seal off and the subsequent growth the tree produces is weak and subject to break during storms making the tree even more dangerous. Look for a reputable tree care company that can remove the overhanging limbs. If the overall size of the tree must be reduced a qualified tree company can prune with a technique called crown reduction. Crown reduction minimizes stress on the tree, preserves the natural appearance and is used when the height and spread of individual branches need to be reduced. The winter or dormant season is the best time to prune your tree.

I saw a vine growing up some mature trees that looked somewhat similar to English ivy but it had clusters of dark blue berries on it. The vine looked very dense and I assumed it was something invasive. Would you know what this vine was?

What you saw was English ivy and yes, English ivy is a notorious and destructive alien invasive plant. Unfortunately, it is still sold at nurseries as a groundcover. When it grows on the ground, it is in a juvenile stage, but when it climbs up a tree or structure it goes into a mature stage.  Once it gets to the mature stage, it blooms and produces berries which wildlife, mostly birds, spread into our parks and natural areas. There it displaces native plants, eliminating an important food source that wildlife needs to exist. So obviously English ivy is a groundcover we no longer recommend for the landscape.

I have a weeping cherry tree that has some holes in the trunk. Sap is dripping out of them and is even dripping to the ground. So far the tree looks pretty healthy. Could this be some sort of insect infestation and what can I do to help the tree?

The oozing sap is called 'gummosis' and generally happens any time an injury occurs to the bark of a tree. Gummosis can be caused by many factors such as insects, mechanical damage, diseases, or weather. Pushing out sap is the trees attempt to protect itself by flushing out pathogens or insects. (PDF) Ornamental cherries are prone to both borers, which are insects that bore into the tree, and canker diseases. Both of these conditions are serious and unfortunately can’t be cured once they attack the main trunk of a tree.  However, in many cases the tree continues to do okay and can remain viable for a few years. If the tree has borers or a canker disease it will start losing branches and then will eventually have to be removed.  These trees are generally not long-lived and have an average lifespan of about 25 years.

It is only August and the leaves of my dogwood tree are showing fall color. There are flowers planted underneath it which I water on a regular basis. I assume the tree has had enough water. Should I be concerned about my tree?

It is too early for trees to be showing fall color. Early fall color is a symptom of a tree under stress. Stressors including drought, poor fertility, insects, and diseases such as powdery mildew can cause this to happen. We did have a very hot, dry summer. Even though you were watering the flowers most likely the tree did not receive enough water. Frequent, shallow watering encourages surface roots and is not the proper way to water a tree.  Mature trees should be watered less frequently but for a longer period of time. Place a soaker hose or turn your hose on at a very slow trickle, moving it around the root zone of the tree periodically, at the dripline (the edge of the tree’s leaves and outward) and let it run until the soil is moist 4-6 inches deep. Check with a soil probe to see how deeply the water is penetrating. During drought periods do this once every two weeks or so, but do let the soil dry out between waterings.

My neighbor’s tree is overhanging their fence and shading my vegetable garden. What can I do so that my garden can get more sunlight?

Maryland has adopted the so-called Massachusetts Rule that limits a landowner’s remedy against encroaching vegetation to “self-help” in nearly all circumstances. A landowner must assume responsibility for the care and preservation of his/her own property. Under the “self-help” rule, a neighbor can cut back encroaching limbs or roots of an adjoining neighbor’s tree to the property line, but they:

  • May not destroy the tree by the pruning;
  • May not cut down the tree itself;
  • Must stop at the property line, unless they have the neighbor’s permission to cross.

Any person who trespasses and removes trees, unless they work for a public service company or a public road agency is liable for any surveys or appraisals needed, any court costs that may incurred, and triple the amount of the value of the trees or timber cut. (credit: Maryland Licensed Tree Expert Exam Study Guide: Chapter 1, Tree Laws)

We have a row of Leyland cypress trees that are rapidly turning brown.  They look like the needles are being eaten by something.  I see these cocoons on the branches and was wondering if they have anything to do with the trees declining?

Your Leyland cypress trees are infested with bagworms. This is a native insect that can cause serious damage to many species of evergreen trees and shrubs.  Most people notice the damage and do not realize that this pest has been feeding on their plants since early June. The bags are initially very small and as the caterpillar feeds the sacs grow to about 2 inches.  They are made from silk that is covered with plant parts. The adult is a moth that breeds in late summer.  The female lays eggs inside the bag that overwinter and hatch in early summer.  A heavy infestation of  this insect  needs to be controlled. Early in the season when the caterpillars have just hatched out use Bacillus thuringiensis (B.t.).  About mid-July, when the caterpillars are larger use a residual insecticide or one that contains spinosad.  During the rest of the year pick off and dispose of any bags that are found on the tree. 

Please send us a question at Ask the Experts if you have a tree question you would like answered. Digitial photos can be attached to your question.

FAQs - Trees Fall/Winter

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