Frequently Asked Questions
Trees are one of your property’s most valuable assets, providing shade, oxygen, pollution control, flood abatement, energy savings, and aesthetic value. These tree-related questions are most often posed to TSU extension agent Karla Kean and UT extension agent David Cook. Additional information is provided by the Metro Nashville Tree Advisory Committee.
When to plant a tree?
The best time to plant B&B trees is in fall to late winter (November through February).
The best time to plant a tree was 20 years ago.
The second best time is now. –Chinese Proverb
How to select the right tree?
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How do I decide what type of tree to plant?
Tree selection and placement are two of the most important decisions a homeowner makes when landscaping a new home or replacing a tree. Many trees have the potential to outlive those who plant them, so the impact of this decision can last a lifetime. Matching the tree to the site benefits both the tree and the homeowner.
One of the most common tree care questions is: “Which kind of tree should I plant?” Before this question can be answered, a number of factors need to be considered:
- Why is the tree being planted? What functions will it serve?
- Is a small, medium, or large tree best suited for the location and available space? Do overhead or belowground utilities preclude planting a large, growing tree — or any tree at all? What clearance is needed for sidewalks, patios, or driveways?
- What are the soil conditions? Is enough soil available of sufficient quality to support mature tree growth?
- How will necessary maintenance be provided? Will someone water, fertilize, and prune the tree as needed after planting?
Answering these and other questions can help you choose the “right tree for the right place.” MORE
How to select the right site?
First, look up. Are there obstructions overhead like powerlines or large tree branches? Plant small trees or plant elsewhere. Look left and right. How close are you to other trees, houses, roadways? A large mature tree can require up to 30 feet on each side. A common mistake is planting trees and shrubbery too close to your house. Give them plenty of room to grow without running into your house.
How to plant a tree?
How do I plant a tree?
- Plan before you plant. Choose a tree that fits the site—or vice versa. Find out your tree’s estimated height and width at maturity, and plant accordingly. Don’t plant too close to buildings or other trees. And don’t forget to look up! Don’t plant under powerlines.
- Dig a hole twice as wide as your rootball in the shape of a wide V. Dig deep enough that the rootball sticks up about two inches above finished grade.
- Fill the hole with water and let it drain before you put the tree in the hole.
- Remove twine and burlap as much as possible. Cut wire baskets if you can’t remove them. Always remove tape or rope around the trunk.
- Fill the hole with soil and water thoroughly to settle the soil and remove air pockets.
- Add mulch to a depth of three to four inches around the tree. Don’t make a mulch volcano! Leave a couple of inches of clear space around the trunk so the mulch doesn’t touch it.
- Water your new tree regularly for the first two years of life, especially during periods of drought.
How do I plant a seedling?
- Dig a hole twice the size of the roots and deep enough to hold all of the roots.
- Place the tree in the planting hole as shown below. Make sure not to plant the seedling too deep or too shallow. Allow for proper root spread and do not let the roots curl back up to the top.
- Fill in the planting hole with soil around the roots. Do not add fertilizer or soil amendments.
- Water the seedling well. Give your trees a good soaking once a week, more during droughts.
- Protect your trees from weed eaters, lawnmowers, weeds, and grass. While the seedling is small, tie a bright ribbon in its top. Together with a wooden stake inserted at the base, the seedling will be more noticeable and less likely to be damaged.
How to water your tree?
How do I properly water my trees this summer?
Watering is perhaps the most important step in caring for a newly planted tree. With differing climates and varying landscapes, it’s hard to quantify how much water trees need because irrigation will vary from one species to the next. Young trees and those transplanted will call for more water because they’re burning a lot of energy establishing their roots in the soil. MORE
One rule of thumb is that the tree should receive at least one inch of water per week, whether it comes from rainfall or watering. Forget about a quick dribble while you stand there holding the garden hose. Give it a slow, extended soaking for a couple of hours or more. Trees need watering regardless of the season, even during the winter.
Appliances such as gator bags and water rings let you fill them quickly and drain slowly.
How to mulch your tree?
How to fertilize your tree?
Several factors should be considered when deciding whether to fertilize. Note the general vigor of the plant and the color of the foliage. Abnormally small leaves and short new twig growth generally indicate a need for fertilizer. Yellow (chlorotic) leaves may be another symptom of a lack of soil nutrients. A soil test should be the first step to determine if a fertilizer is needed. The soil test will provide information on the soil pH and available nutrients. It also provides an objective basis for determining how much of those materials to add when they are found to be deficient. The best time to fertilize trees extends from late fall, after the leaves have fallen, through the winter and into early spring before active new growth occurs. Fertilizer applied in the fall has a longer time period to penetrate the soil enabling the roots to more efficiently absorb it. MORE
Do not top trees.
Not only are the trees ugly but topped trees are not healthy trees. Topping leaves entryways for insects and disease to invade and destroy. Topped trees also are not safer because they’ve been topped. In fact, new growth is much weaker and a hazard for falling.
Topping is unnecessary and expensive. Let a professional take care of your trees. Look for companies that advertise a certified arborist on staff, are licensed and bonded, and/or show membership in a professional arboriculture association (such as ISA, Tree Care Industry Association). ISA Certified Arborists are held to a Code of Ethics and are encouraged to follow industry standards. Certification demonstrates the individual has the knowledge to perform tree work correctly, but does not guarantee the quality of the work performed by that individual. MORE
How to choose an arborist?
Look for companies that advertise a certified arborist on staff, are licensed and bonded, and/or show membership in a professional arboriculture association (such as ISA, Tree Care Industry Association). ISA Certified Arborists are held to a Code of Ethics and are encouraged to follow industry standards. Certification demonstrates the individual has the knowledge to perform tree work correctly, but does not guarantee the quality of the work performed by that individual. MORE
Trees and Powerlines
NO! Any tree pruning near power lines needs to be done by a professional tree service. Call your local utility service or a certified arborist and have them pruned properly. If you must plant under or near powerlines, choose Powerline Approved Trees. When planting trees, leave an adequate buffer between trees and lines; large trees can require 30 feet or more.
Fill soil is frequently added around existing mature trees to cover roots and re-establish turf. Fill soil can reduce soil oxygen levels and suffocate tree roots. You should not add more than three to four inches of topsoil to the root zone and in most cases the roots will find their way back to the surface eventually. You may have a hard pan or compacted soil which is keeping the roots from growing downward. Maples are just one of those species that tend to have surface roots. I would suggest applying three to four inches of mulch out to the dripline of the tree so that you do not have to mow this area.
Tree Insects & Diseases
The needles on my arborvitae are slowly losing their dark-green color and turning a dull gray-green color. Is this an indication of water stress?
The loss of green color on an arborvitae is usually caused by the feeding activity of the spruce spider mite. Despite its common name, this mite feeds on more than 40 species of conifers and is found in most of the conifer areas of the world. Start scouting early in the year for this pest because it becomes active in early spring. Due to its extremely small size do not expect to actually see live mites on your trees. Instead, look for visual symptoms of feeding activity. When plant foliage begins to show off-green color and mites are suspected, make a foliage inspection. The best method of detection is to place a white sheet of paper under a branch and then shake the branch to dislodge any mites onto the white sheet. If mites are present, they will fall onto the paper and look like tiny green, mobile specks. A hand lens would be helpful in viewing the mites. Spruce spider mite feed and destroy the chlorophyll bearing cells located on the surface of the needle or leaf scale of the host tree. This injury shows up as whitish or yellowish stippling or flecking. Severe feeding may result in a “bleached out” appearance of the foliage. Control of spider mites depends on thorough application of a miticide when the mites are active. A second application should be made in 7 to 10 days, unless prohibited by the label. MORE
What are those brown bags hanging from my arborvitae and redcedar trees?
Those are bagworms. Control options include chemical sprays and hand removal. Chemical sprays should be applied when the caterpillar moths are outside the bag and actively moving around. MORE
Bacterial Leaf Scorch
Bacterial leaf scorch is a chronic disease caused by a bacterium, Xylella fastidiosa, that grows in the xylem of the tree and physically clogs these water-conducting vessels. As the bacterium multiplies, water transport becomes more limited. The tree suffers water stress, especially in mid to late summer, resulting in leaf scorch; a browning or discoloration of the margins of the leaves with interior portions of the leaves near the veins remaining green MORE
Powdery mildew is one of several diseases that threaten the beauty of these native trees in home and commercial settings. Powdery mildew can be managed by using cultural practices, planting resistant dogwoods, and by using fungicides. MORE
The black colored foliage on the hackberry trees is caused by a fungal growth commonly referred to as sooty mold. The black mold is not attacking the leaves, but is feeding on the liquid waste from small insects called Asian woolly hackberry aphids. The issues associated with this aphid are the sticky waste excrement, commonly referred to as honeydew, and the black mold that grows and feeds on the honeydew. Aphids have mouthparts that only allow for the intake of liquid foods such as plant sap. Thus, their waste product is excreted as small droplets of a sticky liquid (honeydew). As the honeydew drips off the leaves of hackberry trees, anything below the tree also becomes a sticky mess. The aphid population reaches a peak in late summer to early fall, and this is when the problems occur. The aphid population will die off, but not after the female aphids have laid overwintering eggs on the trees. In the spring, new generations of aphids will emerge from the overwintering eggs and the cycle will repeat itself. MORE
This dieback, which resembles a blight, is most likely being cause by a particular insect called the hickory leaf stem gall aphid. It damages trees by causing the development of galls, or swellings, on petioles and occasionally new shoots of hickory. In spring and early summer the galls are green, leathery, and bullet shaped, varying in size from a pea to a half-inch or more in diameter. The galls may be round or irregular in shape. The tree owner becomes concerned when in mid to late summer, the leaves fall prematurely. This pest is not likely to cause serious damage to mature trees. However, the aphids can cause major damage to small, newly established trees and trees in nurseries. Control should be considered if the tree is not big enough to withstand attack. MORE
My junipers are turning brown at the tips. What could be causing this?
There are two main diseases that would cause tip dieback: Kabatina Tip Blight and Phomopsis Tip Blight. Kabatina Tip Blight produces spores during the fall but they are not evident until the following spring. Unlike phomopsis tip blight, kabatina tip blight is an opportunistic invader and infects damaged tissue caused by insects or mechanical damage. Spores of phomopsis tip blight are produced during damp, rainy periods of spring or fall and infect new tissue. Older growth is resistant. Cultural controls for both diseases includes removal of all blighted twig tips which then should be burned or buried to eliminate the sources of infection. Pruning or shearing should be done on a dry day to reduce spread of the fungus to other plants on wet tools. MORE
Leyland cypress trees are not the best suited species for our environment here in Tennessee. They tend to be over planted, become drought stressed and develop a fungal canker disease. If only a few limbs are affected you can prune below the canker and destroy all cuttings. You also have to disinfect pruning tools in between cuts or you can spread the disease that way. MORE
Maple / Sugar Maple
The leaf fall is the result of an insect feeding inside the leaf petiole. This injury, caused by a tiny insect called the Maple Petiole Borer, does not cause any serious harm to the tree even though it might appear that the tree has lost a large percentage of its foliage. The maple petiole borer is a type of sawfly. Sawflies are not flies, but are small non-stinging wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plants where they lay their eggs. Although several species of maple are subject to attack by this insect, sugar maples are preferred. Adult sawflies emerge in early to mid-April. After mating, the female uses her ovipositor (egg-laying structure) to puncture the petioles and lay a single egg near the leaf blades. After hatching, the larvae tunnel and consume the contents of the petioles about one-half inch from the leaf blade. After a short period of time, the petioles break and damaged leaves fall to the ground (during late April to May). Maple petiole borer infestations are infrequent and unpredictable and there is only one generation per year of this insect. Also, they do not appear to harm tree health so insecticidal control is not recommended. MORE
What is causing the round holes arranged in horizontal rows on the trunk of my maple tree? Is my tree being attacked by wood-boring insects?
The round, horizontal holes are actually being caused by a particular bird called the yellow-bellied sap sucker. The yellow-bellied sap sucker (Sphyrapicus varius) is a member of the woodpecker family. Although insects make up part of its diet, the sapsucker is better known for its boring of numerous holes in the bark of live trees to obtain sap, the activity from which it derives its name. The yellow-bellied sapsucker is the only member of the woodpecker family to cause this type of injury. More than 250 species of woody plants are known to be attacked. Early in the spring the sapsucker tests many trees around its selected nesting site by making sample drillings before selecting ones it prefers. These trees, because of quantity or sugar content of the sap, are visited several times a day for the rest of the season and sometimes are used as a food source for several years. To discourage sapsuckers from feeding on a favorite shade tree, wrap hardware cloth or burlap around the area being tapped or smear a sticky repellent material, such as bird tanglefoot, on the bark. MORE
My pin oak tree is covered with these large balls with spines sticking out of them. Most of the tree is covered and the tips of branches are starting to turn brown and die. What is going on?
Sounds like horned oak gall and we have seen a lot of it this spring (2014). Although gall-inducing insects usually are not considered important pests in urban landscapes, the horned oak gall wasp, Callirhytis cornigera (Osten sacken), is a notable exception. If the tree is young and small you may have some success with pruning out the galls. No insecticidal control chemicals can be recommended at this time. MORE
Shot hole disease is a common disease of ornamental cherry which is quite often mistaken for insect damage. According to plant pathologist Alan Windham most ornamental cherry cultivars can tolerate shot hole without significant long term damage. Cover sprays with fungicides starting at bud break or nearly so would be necessary to get good control; if you wait until June, the cover spray will have little to no affect on controlling the disease. MORE
More than likely it is Fire blight, caused by the bacterium Erwinia amylovora, which is a serious disease of apple and pear. This disease occasionally damages cotoneaster, crabapple, hawthorn, mountain ash, ornamental pear, firethorn, plum quince, and spirea.
Those are bagworms. Control options include chemical sprays and hand removal. Chemical sprays should be applied when the caterpillar moths are outside the bag and actively moving around. MORE
Most likely you have Tulip Poplar Scale. Scale control can be challenging and may need to be repeated over several seasons. This is due in part to the protection from contact insecticides provided by the waxy coverings over immobile, mature scales. Proper timing of insecticide applications is a major key to success. Applications must target newly hatched scale crawlers which are active in August. Crawlers are very susceptible to control measures as they move over plant surfaces to find a feeding spot. Once settled on the plant, they begin to secrete a covering and are protected by it. MORE
Despite the name, evergreen foliage does not live forever. Actually evergreen foliage lives from one to several years, depending on the species. As new growth emerges in the spring, last year’s growth becomes shaded and is no longer the plant’s primary food. During fall, this inner or older foliage dies and falls away. This phenomenon is a natural one called Fall Needle Drop. It is normal for pines to drop their oldest (inner) needles at this time of year. Natural needle discoloration may be more noticeable on trees that have experienced root stress due to less than optimal growing conditions. Extended dry periods during the summer months, as well as sites with poorly drained, heavy clay soils may accentuate root stress to pines. If the newest growth (this year’s needles) is still green and healthy in appearance, you can rest assured that this yellowing phenomenon is natural.
Leaf Spot Diseases
Leaf spots that appear on the foliage of trees and shrubs are generally caused by fungi. Fungal leaf spot diseases are the most common type of plant disease, but generally no serious harm is done to the plant. Most of these diseases are favored by cool weather, light and frequent rains, fog or heavy dew, high humidity and crowded or shady plantings. Most of the fungi that cause leaf spots are fairly host-specific and do not move casually to a wide range of different plant hosts. However, since they all require very similar environmental conditions for infection, they often appear on different hosts at about the same time. There are no fungicides for purchase that will make leaf spots disappear. Fungicides may be used on diseased plants to protect foliage not yet infected or to protect a new flush of growth from disease. MORE
This unsightly webbing is caused by numerous caterpillars called fall webworms. Fall webworms attack at least 88 species of trees in the United States, but are more frequently observed on nut-producing trees such as pecan, walnut and hickory. No serious damage is done to the trees as the colony of caterpillars only feeds on the foliage they enclose in their silk webbing. At the end of the summer the mature caterpillars leave the host tree to find places to pupate into moths. Chemical controls are generally not needed. MORE