Growing Grass in Shady Locations

Source(s):

  • Kim Coder, Warnell School of Forestry, The University of Georgia.
  • Gil Landry, Center for Urban Agriculture, The University of Georgia.
  • Bob Polomski, Extension Consumer Horticulturist, Clemson University.
  • Debbie Shaughnessy, HGIC Information Specialist, Clemson University.

Shade is a wonderful benefit of trees but a major challenge for growing turfgrass. Although growing grass under trees is difficult, there are some important tree and turfgrass management principles involved in successful coexistence. Basic management practices for growing grass under shaded conditions consist of proper turfgrass selection, cultural practices, pest management, environmental modification, and traffic control.

Shading below 55% of full sun or about 4 hours of sunlight per day can initiate many low light related problems. The lack of sufficient sunlight reaching the grass causes a reduction in photosynthesis, which is the process that produces energy for growth. As a result, lawn grasses have lower tolerance to heat, cold, disease, drought and wear stress.

Competition with trees and shrubs for limited nutrients and water also reduces vigor, as many shrubs and trees will have root growth in the same area as the grass roots. Disease problems are often more severe in shade due to higher humidity, reduced air circulation, and prolonged dew retention. As a result of these factors, turfgrass grown in the shade often begins a steady decline in density, especially as trees and shrubs mature.

Turfgrass Selection

Certain turfgrasses perform better in shade than others. Of the cool-season grasses, tall fescue is a common choice in Georgia. Fine fescues may perform well in some situations. Of the warm-season grasses, St. Augustine grass exhibits the best tolerance to shade. Recommended St. Augustine grass cultivars for the coastal and midstate areas include Raleigh, Palmetto and Mercedes. Zoysiagrass is more tolerant to light or moderate shade than centipedegrass, but neither will survive heavy shade. Zoysiagrass cultivars that have good tolerance to shade include El Toro and Cavalier. Meyer has fair tolerance, while not much is known of the relative shade tolerance of Empire. Bermudagrass exhibits extremely poor tolerance to any shade.

It is important to remember that fine and tall fescue are adapted to north Georgia, while dependent on the variety, zoysiagrass, centipedegrass, and bermudagrass can be grown throughout the state.

When establishing cool-season grasses, it is best to seed or sod early enough in the fall so there is sufficient time for the turfgrass to mature before leaves cover the ground. During the fall remove leaves by raking, blowing or bagging when mowing to prevent smothering of the grass. Cool-season turfgrasses will grow long after deciduous trees have dropped their leaves.

Cultural Management

  • Raise the mowing height to the highest recommended height. This increased leaf area helps the plant capture more sunlight and thus manufacture more “plant food”.
  • Nitrogen needs for turfgrasses are generally 50% lower in shaded environments than recommended for full sun. This generally means no more than one to two pounds of nitrogen per 1000 sq. ft. per year. This should reduce lush growth which is more prone to disease problems and temperature and drought stress. Since most turfgrasses and trees require the same amounts of fertilizer, soil testing should be used to determine lime and fertilizer needs. Surface applications of fertilizer are generally preferred for trees and turfgrasses. Concentrating fertilizer in holes, especially if holes are deeper than five inches, is not recommended. Finally, fertilizer or fertilizer plus herbicide should never be placed directly on exposed tree roots.
  • Irrigate deeply and infrequently to encourage deeper rooting and to reduce the humidity and time the grass leaves are moist. Since moist conditions encourage disease, irrigate in early morning.
  • Remove tree leaves, grass clippings, and any other debris that might prevent light penetration or encourage disease activity.
  • Follow a good pest management program to reduce competition from weeds, and injury from diseases and insects. In shade environments, preemergence herbicides are not typically needed for weeds like crabgrass and goosegrass, which are full sun plants that generally do not grow in low light conditions. However, this class of herbicides may be effective against other weeds that can grow in the shade. Read and follow label directions that are printed on the product.
  • Control traffic to reduce wear injury. The added stress of traffic can easily cause the loss of grass in shaded areas.

Pest Management

Most of the same disease problems exist in both shady and sunny areas. Those diseases associated with high moisture and/or high humidity may be more serious in shady areas because air movement is reduced and surface moisture remains longer. Proper cultivar selection and turfgrass management practices are key to reducing the severity of these diseases.

Environmental Management

Ornamentals that have dense canopies and shallow roots normally make turfgrass survival difficult even if proper management practices are used. When possible, select trees and shrubs that are deep-rooted and have relatively open canopies. Some species that generally cause fewer problems include sycamores, many oaks and most elms. Undesirable species include ash, willow, poplar and some species of maples.

Some measures can be taken to aid grass survival, whether desirable or undesirable ornamentals are present. Selectively prune branches, particularly low branches, to aid in air movement and light penetration. Ideally, the lowest branches of trees should be more than 8 feet above the soil surface. Remove any unnecessary trees and shrubs. Use recommended species and sufficient spacing between plants when placing new plants.

Consider other alternatives if quality grass cannot be maintained, even after following sound management practices and using recommended species and varieties. Two options you may consider are:

  1. Removing ornamentals;
  2. Planting an appropriate shade-tolerant groundcover — such as English ivy, ajuga, liriope and pachysandra rather than a turfgrass.

For additional information on turfgrass management, visit the University of Georgia turfgrass webpage.


Resource(s): Lawns in Georgia

Center Publication Number: 205

Drought Damages Stately Trees

Source(s): Kim Coder


The trees that line our city streets and properties have endured decades of stress from:

  • heat and cold,
  • root-crimping sidewalks,
  • smog,
  • insects and disease.

picture-beech4

Unfortunately, many older trees may have met their match in this year’s severe drought.

Arborists are warning the intense drought will likely do the most damage to our grandest trees. “There is a public perception a lot of times that those are just untouchable, so nothing can hurt them,” said Kim Coder, professor of tree health care at the University of Georgia’s Warnell School of Forest Resources. “It’s actually the opposite. The old trees are much easier to stress out and damage than younger trees.”

It’s too early to tell how extensive the loss will be. Steady rain over the next few months would ease trees’ suffering. “But if we remain in a droughty cycle, this spells disaster for a lot of these trees,” Coder said. In addition to the drought, a late spring freeze and waves of 90+ degree scorchers this summer has made this a stressful year for trees.

The scope of this year’s damage won’t become clear until May. Dr. Coder also warned that an ice storm or cold front in the next few months could send weakened limbs tumbling. And spring rains could make trees more likely to topple. Roots shrink away from the soil in a drought. When it finally does rain, winds can cause them to pull out of the ground.

For some trees, the drought may spur a decline over two or three years. That decline could be aided by:

  • ambrosia beetles
  • root-rot fungus
  • mistletoe.

In urban areas, the drought just makes a tree’s life harder. Concrete and asphalt stress trees by confining roots and branches as they reach for water, light and soil. Many cities have passed tree ordinances to stop people from removing trees.

Homeowners should be thinking about replacing trees as there is likely to be a large-tree loss from this year’s drought. Fall and winter are the right time to plant new trees, even if it’s not clear when their older neighbors are going to succumb. Watering restrictions make planting somewhat difficult, but reused or “gray” water from the house should be enough for a new tree.

Here are a few things tree lovers can do to help their trees survive:

  • no heavy fertilizer or pesticides use,
  • add mulch 2 to 4 inches deep,
  • do not overwater.

Resource(s): Landscape Plants for Georgia

Reviewer(s):

  • Maria E. Abreu, CEA- Gwinnett County, The University of Georgia College of Agricultural and Environmental Sciences.
  • Chuck Cornwell, Program Assistant- Forsyth County, The University of Georgia College of Agricultural and Environmental Sciences.

Center Publication Number: 255

Protect Landscape Trees from Drought Injury

Source(s): Kim D. Coder, Professor of Community Forestry, Warnell School of Forestry and Natural Resources, The University of Georgia

 


Trees across Georgia are declining due to drought. Drought stressed trees may have fewer or smaller leaves. Small or large limbs or the entire tree may die. Although trees can withstand some drought injury, some trees may require months to years to recover. Trees may not show damage immediately. When they do, it may be too late to save them. Protect trees now from drought with proper care.

drought

How to Water

The best ways to water trees are by soaker hose or drip irrigation. Automated lawn sprinklers are less efficient for applying water to trees. Even a garden hose, moved often, can provide a good soil soaking. Use a light organic mulch to conserve moisture and apply water over the top of the mulch. Do not pile mulch against the base of the tree or allow water to concentrate at the base of the trunk as this can lead to pest problems.

Where to Water

Most of the tree’s absorbing roots are in the top foot of soil. Applying water deeper than this misses the active roots and wastes water.

Lay-out water hoses or applicators out to the tree crown edge (drip-line). Water the soil areas directly beneath the foliage and shaded by the tree. Do not water beyond the drip-line and do not water closer than 4 feet to the trunk base on established trees.
Use mulch and slow application rates on slopes, heavy soils (clays), and compacted soils to assure water is soaking-in and not running-off. Do not spray tree foliage when applying water. Water droplets on tree leaves can lead to pest problems. Try not to wet the tree’s trunk.

Young, newly planted trees need additional watering care. Water has limited horizontal movement in soil. You must apply water directly over where you need it in the soil. For new trees, concentrate water over the root ball, as well as the planting area.
Old, large trees can be watered over the entire area under their foliage. Another method in watering large trees is to water roughly 1/3 of the area within the drip-line.

When to Water

The best time to water is at night from 10 p.m. to 6 a.m. Trees refill with water during the night. Watering at night reduces losses to evaporation and assures that more water moves into the soil and tree.

For every 18°F increase in temperature, the amount of water lost by a tree and the site around it almost doubles. Consider this when watering trees. Trees surrounded by pavement and other hot, hard surfaces can be 20-30°F warmer than a tree in a protected, landscaped backyard. Water use rapidly climbs with increasing temperatures, and so should water application volumes.

How Much To Water

Depending upon soil texture 1 to 2 inches of water per week should sustain a tree. Trees in limited rooting areas, in containers or pots, or on major slopes, need additional care to assure water is reaching the root system in adequate amounts and not suffocating roots from lack of drainage. Five gallons per square yard is about 1 inch of water.

Fine soils (clays) require careful attention to prevent over- watering and root death. Sandy soils can dry out rapidly since water runs out of the rooting zone quickly. Composted organic mulch on the soil surface can help prevent rapid loss of applied water.

How Often To Water

Water trees once or twice a week (minimum of 1 inch per watering) in the growing season if there is no rainfall in that particular week. A few heavy waterings are much better than many light, shallow waterings. A greater proportion of the applied water is used by the tree with heavy, infrequent watering. Once you begin watering, continue to water until rain comes.
Drought is the main cause of tree decline but beware of other factors that damage roots and lead to long-term tree decline and death.

  • Do not fertilize or use pesticides on severely drought stressed trees.
  • Do not dig or drive under the canopy of trees or do other things that kill or crush roots.
  • Do not pile soil under tree canopies. When adding soil to cover roots etc., add no more than 1 inch per growing season. Protect the critical root zone of the tree. Measure the trunk diameter at chest height in inches. Multiply this by one and a half. This will be the size in feet of the radius of the circle that you must protect around the tree. For instance, a 20 inch diameter tree would have a critical root zone with a radius of 30 feet. Avoid digging, piling soil, trenching or driving through this area.

Call your local Extension Agent at (800-ASK-UGA1) or Locate your local Extension Office Georgia Extension Office Locations


Center Publication Number: 267

Shade Tree Decline

Source(s): Kim D. Coder, Professor of Community Forestry, Warnell School of Forestry and Natural Resources, The University of Georgia


Many trees in Georgia are showing dieback and decline symptoms. Twig or branch dieback is initiated in the tree as a response to poor growth conditions and/or pest attack. Usually a combination of physical, climatic and pest problems lead to the tree shutting off some of its outside portions.

shadetree

Tree decline is a general loss of vitality throughout the entire tree caused by a systemic disease or by a sequence of stressing events that cause the tree to burn too much food energy. Many cultural factors as well as past tree abuse predispose a tree to decline. Several factors contributing to this decline include, drought, mechanical injury, chemical injury and pests.

Drought

Drought is a main contributing factor to shade tree decline. Extended drought can influence the health of shade trees by the loss of absorbing roots which are found primarily in the top 8 to 12 inches of soil. Once this soil area dries, many of the tree’s absorbing roots dry out and die. Leaves and stems can also be damaged by drought conditions, especially when there is not enough water available for evaporative cooling and food production.

Some types of trees will be inherently more susceptible to drought damage that occurs in mid-spring as compared with a summer drought. A season-long drought period with high temperatures can adversely effect all trees even if supplemental water is added. Trees may not readily show initial symptoms because of stored carbohydrates and essential elements in the woody tissues. As soon as these stored foods are near depletion, the trees begin to prematurely defoliate. Other drought symptoms can be delayed two or more years making it hard for many to believe that drought was actually the problem.

Although irrigating trees during periods of drought is recommended, frequent and shallow watering contributes to shallow root development. This increases the chances for drought injury as well as the potential for winter injury during periods of extremely cold weather. When watering, be sure the moisture reaches depths of at least 5 to 7 inches. Water once every three to four days during periods of severe drought. Watering everyday may contribute to the decline of the tree because the activity of many parasitic and pathogenic organisms, like root rot, is stimulated by too much water. The amount of water to apply depends upon soil texture and potential size of the tree rooting area. Clay soils can be easily overwatered which destroys tree roots.

Mechanical Injury

In urban areas, mechanical injury is a major cause of shade tree decline. In subdivisions and new housing developments, shade trees are often abused; roots are torn out of the ground, bark is bruised and the soil around trees is disturbed. Losses from such damage could be minimized or even avoided if people realized that trees may not survive such treatment and took precautions to avoid abusing them. Many utilities and municipalities are also guilty of tree abuse. When putting in gas and water lines or paving streets, workers damage or destroy roots which disturbs food production, growth control and the tree’s top-root balance. Root loss contributes to the weakening and decline of a tree’s crown. As with drought, these symptoms can often be delayed in appearance by 1 to 2 growing seasons.

Some of the worst things you can do to a tree are: add fill around the trunk, cultivate or remove soil from around the trunk, compact the soil, especially when the soil is wet, or damage the bark on the trunk. Each of these events leads to a weaker tree that can lead to other stress factors or pests injuring the tree further.

Chemical Injury

Chemical damage (pollution/pesticides) of trees is very common. Injury to trees from pollution as well as chemical application by homeowners and commercial applicators, are common occurrences. Pollutants are now a part of our urban and rural environment and ecology. Pollutants, such as ozone, sulphur dioxide, fluorides, sunlight-induced nitrates (PAN), road and sea salts and particulate matter (flyash, dust, cinders), all disrupt the life processes of trees. Some pollutants will be concentrated near roadways and factories that are their source. Other pollutants, like ozone, can disrupt tree growth a hundred miles downwind from a city. Pollution acts as one factor in a tree decline problem.

Chemical injury can be much more severe when trees are already weakened by other factors. The “spray and pray” concept (spraying a chemical and hoping it will control whatever the problem is) should be avoided. Chemicals are not always the answer and may actually create more problems. Good tree management should be practiced first. Use chemicals only as helpers after other management practices have been performed.

Pests

All of the factors already mentioned, and others not mentioned, weaken trees and make them more susceptible to pest organisms. Disease organisms are especially likely to take advantage of a weak tree.

  • Tree Cankers: Many oak species are lost to Hypoxylon canker, a disease that is common in both urban and rural areas. This disease can be diagnosed by its grayish to brown felt appearance on the bark. Little can be done to control this disease since the fungus is actually growing into the wood of the tree. The removal of infected trees and pruning of infected branches will remove the fungus innoculum from the area. However, pruning will not solve the problem of low tree vigor. Careful management practices performed to increase tree vigor will encourage tree recovery.
  • Twig Cankers: There are a number of canker-causing fungi which cause twig dieback in many shade tree species. Most are diseases that take advantage of trees that are in a weakened or declined condition. Prune dead wood and initiate management practices to help the tree recover. Fungicide applications generally provide little protection since tree health is the key to canker disease control.
  • Leaf Spots: There are numerous leaf spot fungi which infect leaves and cause foliage loss from many urban shade trees. These diseases occur annually and may actually go unnoticed most of the time. During periods of stress, there may be an excessive amount of defoliation attributable to foliage diseases. Foliage diseases of large urban trees are not known to cause any permanent damage unless defoliation occurs several years in succession. Excessive defoliation often occurs when a tree is in a weakened condition.
  • Slime Flux: Slim flux, called wet wood, is considered a disease of unthrifty or old trees. Symptoms of slim flux include oozing of either a white or brown, smelly substance from wounds, pruning scars and trunk crotches. The slime is toxic to the bark and may kill large patches when it stays on the bark for a long time. Rinsing twice a year may minimize the damage, but determine what weakened the tree initially and provide best management practices to improve tree vigor.

Decline Management

What can be done to prevent shade tree decline? The key to good health is tree vigor. Provide a site that is suitable for the species involved. Pick a strong species of tree. Provide construction protection for roots and trunks of trees to reduce accidental injury, soil compaction and to allow adequate room for tree growth. Plan ahead for future development. Street maintenance equipment often injures trees after roadways are widened. If twig dieback is observed, proper pruning will reduce disease susceptibility and improve the tree’s appearance. Remove dead or dying branches. When roots are damaged or lost, continue to water and wait one growing season and then thin the crown. This helps the remaining roots sustain the health of the existing foliage. Water, fertilize and care for the tree only when needed. Do not “kill” your tree with kindness. Give your tree a chance to live a full, healthy life by helping when it has a bad year.

Shade tree decline is becoming much more prominent. Being able to recognize conditions which promote decline and taking steps to eliminate stresses before symptoms occur will save many urban shade trees.


Center Publication Number: 223

Using Gray Water in Your Landscape and Garden

Source(s): Kim D. Coder, Professor of Community Forestry, Warnell School of Forestry and Natural Resources, The University of Georgia


During times of water shortage, slightly used gray water can provide an alternative landscape irrigation source. Separating slightly used (gray) water from sewage (black water) makes good conservation sense.

Daily, homeowners misuse or waste an average of 33 percent of valuable drinking water. Most of this water misuse is for diluting toilet, sink and laundry wastes and from slightly used sink, shower and laundry water. Every day we use many gallons of drinkable water for purposes like landscape irrigation, which could employ gray water.

Gray water is water that can be used twice. It includes the discharge from kitchen sinks and dishwashers (not garbage disposals); bathtubs, showers and lavatories (not toilets); and the household laundry (not diaper water). Using gray water can almost double home water-use efficiency and provide a water source for landscape irrigation.

Unfortunately, many health regulations consider any non- drinkable water as black water or sewage. Many plumbing and health codes do not accept gray water for reuse because of assumed health risks. NOTE: For the legal status of gray water in your community, county and state, consult your local building codes, health officials, sanitation engineers and pollution control officials.
Gray water has few long-term effects on soil. Gray water slightly modifies soil-organism populations and usually initiates no additional pest problems. Changes that do occur are due to the additional water present. Over-watering and extended periods of soil saturation with gray water can cause severe root problems for plants.

Household levels of bleaches and detergents do not cause problems when gray water is applied to medium and fine-textured native soils. However, when applied to coarse sandy soils with little organic matter, root damage can occur.

Organic matter and soil-texture adjustments are critical in raised beds with gray-water irrigation. Do not use gray water on plants with limited root areas or for hydroponics.

Gray water has few detrimental effects on trees and shrubs growing in native soils. Acid-loving plants, however, can have problems because detergents make water more alkaline.

Tips for using gray water:

  • Make trees and shrubs high-priority watering items because of their individual value.
  • Use gray water when natural precipitation and normal irrigation water are not available.
  • Apply gray water to soil. Never spray on foliage, twigs or stems. Never soak bark or root-collar area.
  • Do not spray edible plant parts or soils where water splash can move gray water onto edible plant parts.
  • Do not use on root or leaf crops consumed by people or domestic livestock.
  • Do not use on new transplants.
  • Do not use on indoor trees or other plants with limited rooting space, in small containers, or plants normally under saturated conditions.
  • Always apply gray water at or slightly below the soil surface. Apply over or under mulch, if present.
  • Avoid using micro or regular sprinkler heads that can blow gray-water aerosols downwind.
  • Be careful of applications that apply gray water directly to leaf surfaces of ground covers and turfgrasses.
  • Control gray-water application and infiltration to prevent standing puddles and surface runoff.
  • Test soil periodically to reveal salt and boron toxicity problems.
  • Gray-water use conserves one of our most precious resources. If managed properly, gray water creates few detriments and many benefits.

Resource(s):

Make Every Drop Count

Xeriscape: Seven Steps to a Water-Wise Landscape

Center Publication Number: 253

Care of Young Shade and Street Trees

Source(s): Kim D. Coder, Professor of Community Forestry, Warnell School of Forestry and Natural Resources, The University of Georgia


Young trees in the landscape, less than three to five years old, require special care to insure establishment and rapid growth. Proper early care helps young trees develop an adequate root system and a strong supportive branch structure. The time and expense invested to train a young tree is much less than treating problems as the tree matures.

young_tree

Young trees may require staking, wrapping and corrective pruning. Proper mulching and control of competition can speed growth. In addition, trees require plenty of available water and essential elements for good growth. Young trees need protection from construction activities, lawn mowers and weed eaters, vandals, and pests.

Pruning

Young street and shade trees require proper pruning. Early pruning improves overall structure and corrects branch defects. Early pruning eliminates problems which become severe in middle and old age. Pruning shade and street trees develops and maintains a central dominant leader. Double or co-dominant leaders (forks) should be removed. Select the main leader early and maintain strong side branches. These side branches become the major limbs supporting the weight of the tree later in life. Remove dead, diseased and broken branches. Prune out deformed and crossing branches.

Many side branches should occur singly (alternately) on shade and street trees. However, trees such as ash and maple frequently have major branches occurring in pairs across the main stem. They can be pruned alternately up to 12 to 18 feet. Select and maintain major side branches spaced 24 to 36 inches apart on alternating sides of the stem. Also, select branches with wide angles of attachment, 60 to 90 degrees between the trunk and the branch. remove all waterspouts and basal sprouts.

Staking

Most established young trees can stand alone against wind and not be staked. Young trees with excessively long new shoots or those exposed to windy sites may require staking to remain upright. Stake young trees that are susceptible to blowing over. Anchorage staking holds the roots or root ball stationary until roots become anchored. Use two or three short stakes for anchorage. Extend stakes 12 to 18 inches above the ground. Loop one tie strap loosely around each stake and around the tree trunk. Low attachment prevents root ball dislodgement yet allows the top to move. Staking is temporary. Be sure to check ties frequently.

Support staking aids trees whose trunks are not strong enough to stand upright or fail to return upright. Support the top about six inches above the lowest level at which the trunk can be held and remain upright. This allows top flexibility while providing support. Support the trunk so it can flex without rubbing against the stakes or ties. This must not damage tender bark or girdle the expanding trunk. Support staking holds the tree upright until it can stand alone.

Wrapping

Newly-planted thin bark trees such as red maple or cherries may benefit from wrapping the trunks at planting. Thin barked trees planted on hot sites are very susceptible to sunscald. Commercial tree wraps or plastic tree guards will protect young trees. Spring planted trees can be susceptible to sunburn. The high temperatures from the summer sun may kill the cambium. Tree wraps insulate the cambium.

Young trees may require protection from sunscald. Sunscald occurs when the cambium of thin barked trees heats up during sunny fall or winter days. Colder temperatures that follow warm periods kill cambium cells in the trunk. Long vertical scars run down the trunk from near the lower most branches to the soil line. Injury usually occurs on the southwest side of the trunk. Thin bark maples and cherries, 4 to 5 inches in diameter, may require wrapping in fall to prevent sunscald.

Tree wraps also protect young trees from girdling by rodents. Start at the base of the trunk and wrap up to the lowermost limbs. Overlap each layer one-half inch. Wrap in the fall and leave the tree wrap on throughout the winter and early spring. Tree wrap is temporary and no longer needed once the tree develops corky bark.

Fertilization

Young trees growing in turf areas that are regularly fertilized do not usually require additional fertilization. Trees showing poor growth require a soil test to determine if essential elements are in short supply. When nitrogen is required, fertilize trees by applying 3 pounds of nitrogen per 1000 square feet of area per year. Make two or three applications, one each in April, June and October(optional) at 1 pound of nitrogen per 1000 square feet. Water each site after applying the fertilizer. Fertilizing trees with a turfgrass or groundcover understory requires multiple applications at light rates to avoid injury to the turfgrass or groundcover plants.

Mulching

Mulches aid in the establishment and growth of young trees. They conserve moisture by reducing evaporation from the soil surface. Mulches reduce erosion and water run-off. Mulches reduce competition and compaction. Mulches can effectively reduce summer soil temperatures to create a more favorable root environment. Organic mulches break down and add essential elements to the soil. Do not mulch wet sites, as mulch materials keep soils overly moist by retaining too much soil water.

To improve growth, mulch young trees out beyond the edge of the canopy. Use three to four inches of an organic mulch. Mulches eliminate the need for groundcovers and turfgrasses beneath young trees, thereby reducing competition for essential elements and moisture. Mulching prevents serious injuries to young tree trunks because there is no need to mow or use string-trimmers beneath trees.

Appropriate mulches include pine bark, pine straw and wood chips. Organic mulches more effectively insulate the soil than inorganic or rock mulches. Pull all mulches back from the trunk four to six inches to prevent diseases from invading the trunk. Rodents may live and burrow in loose mulches, so be alert for these pests.

Improving Growth

You can improve young tree growth by following a few basic cultural practices. First, eliminate competition from turfgrasses and groundcovers underneath young trees. Second, mulch beneath the canopy and out beyond the edge of the foliage to improve the root zone environment. Third, surface apply fertilizers directly to the mulched area. Fourth, water during periods of drought. Fifth, keep lawn mowers and string-trimmers away from tree trunks. These steps will improve growth, even on slow-growing trees.


Resource(s):

Center Publication Number: 224

Watering Trees

Source(s): Kim D. Coder, Professor of Community Forestry, Warnell School of Forestry and Natural Resources, The University of Georgia


Water is the single most limiting essential resource for tree survival and growth. Water shortages severely damage young and old trees alike, and set up healthy trees for other problems. Drought conditions can lead to tree decline, disease and insect problems and non-recoverable damage. Supplemental watering can greatly assist in maintaining tree health during droughts – both during the growing season or during the dormant season.

How To Water

The best ways to water trees are by soaker hose or drip irrigation. Automated lawn sprinklers are less efficient for applying water to trees than soaker hoses or drip irrigation. Even a garden hose, moved often, can provide a good soil soaking. Use a light organic mulch to conserve moisture and apply water over the top of the mulch. Do not allow water to concentrate at the base of the trunk as this can lead to pest problems.

Where To Water

Most of the tree’s absorbing roots are in the top foot of soil. Applying water deeper than this level misses the active roots and allows water to drain away, wasting efforts and water. Apply water across the soil surface and let it soak into the soil. Surface soaking allows tree roots more chances to absorb any water and helps maintain soil health.

Lay-out water hoses or applicators out to the tree crown edge (drip-line). Try to water the soil areas directly beneath the foliage and shaded by the tree. Do not water beyond the drip-line and do not water closer than 3 feet to the trunk base on established trees. Be sure the water soaks into the soil. Use mulch and slow application rates on slopes, heavy soils (clays), and compacted soils to assure water is soaking-in and not running-off. If the tree is surrounded with other landscape plants, or by turf, deep soaking applications will benefit all. Do not spray tree foliage when applying water. Water droplets on tree leaves can lead to pest problems and destruction of leaf tissue through sun damage. Try not to wet the trunk if possible. Young, newly planted trees need additional watering care. Water has limited horizontal movement in soil. You must apply water directly over where you need it in the soil. For new trees, concentrate water over the root ball, as well as the planting area, to assure survival.

Old, large trees can be extensively watered over the entire area under their foliage. Another method in watering large trees is to select roughly 1/3 of the area within the drip-line for concentrated water applications.

When To Water

The best time to water is at night from 9 p.m. to 9 a.m. Trees refill over the nighttime hours. Watering at night allows effective use of applied water and less evaporative loss, assuring more water moves into the soil and tree.

Because trees lose water from day-to-day, month-to-month, and season to season – dormant season watering during winter drought is important, especially for evergreen trees and juvenile hardwood trees that have not lost their leaves. Because of temperature and relative humidity interactions, much less water is required in the dormant season, but water is still needed. Do not water when the soil surface is less than 40°F.

For every 18°F increase in temperature, the amount of water lost by a tree and the site around it almost doubles. This feature of water loss must be factored into applying supplemental water to a tree. Trees surrounded by pavement and other hot, hard surfaces can be 20-30°F warmer than a tree in a protected, landscaped backyard. Water use rapidly climbs with increasing temperatures, and so should water application volumes.

How Much To Water

Depending upon soil texture 1 to 2 inches of water per week should keep a tree healthy. Trees in limited rooting areas, in containers or pots, or on major slopes, need additional care to assure water is reaching the root system in adequate amounts and not suffocating roots from lack of drainage. Five gallons per square yard is about 1 inch of water.

Fine soils (clays) require careful attention to prevent over-watering and root death. Sandy soils can be severely droughty because water runs out of the rooting zone quickly. Composted organic material additions and organic mulch covers on the soil surface can help hold and prevent rapid loss of applied water.

How Often To Water

Trees should be watered once or twice a week (minimum of 1 inch per watering)in the growing season if there is no rainfall in that particular week. A few heavy waterings are much better than many light, shallow waterings. A greater proportion of the applied water is utilized by the tree with heavy watering. Also, light waterings encourage shallow rooting which can lead to more severe drought damage. Once you begin watering you should continue to water until rain comes.


Center Publication Number: 220

Winterizing Trees: Dormant Season Preparations

Source(s): Kim D. Coder, Professor of Community Forestry, Warnell School of Forestry and Natural Resources, The University of Georgia


 

Have you winterized your trees yet? Fall is a time of serious change and reorganization within a tree. Many trees will not survive to grow in another Spring. You can help your trees survive and thrive.

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Trees sense the changing seasons by the temperature, by a dormancy timer in the leaves, and by the amount of light they receive. The old leaves, buds, and inner bark all have a pigment that reads the seasons of the year. As the days shorten in fall, this pigment called phytochrome, tells the tree to close-down for the winter.

Getting ready for winter in an organized way is called senescence. Within a tree, a message is sent from the tissues with phytochrome which signals senescence. Senescence in trees is an ordered shutting-down of summer growth and the conservation of valuable resources. Senescence brings both the fall colors and leads to renewed spring growth.

Many of the materials a tree collected or manufactured during the growth season are withdrawn from soon-to-be dead leaves. Tree waste materials are left behind. The last bit of tree food is stockpiled in the living cells of the outer annual growth rings. Twigs, branches, and roots become the collection sites and warehouses of materials needed for another season to come.

Within the tree, biological doors and windows are being closed and locked. From the moment last Spring’s green leaved expanded and began to make food, winter dormancy has been designed into the tree system. The process of spring and summer growth reset and started a dormancy timer that now hurries the tree preparations.

The tree-filled landscapes this time of year can be mistakenly thought to be asleep. Fall and winter trees are not sleeping, but are simply still — truly counting the days until Spring.

Most of the growing points in the tree are protected inside overcoats called buds. Each growing point waits for the correct message to signal a new season of growth. Only then will it be apparent whether the tree has put aside and saved enough resources to respond to the new season of growth. Winter is a difficult time for trees. Trees must stand in the face of drying and cold winds. Food reserves must be carefully conserved for the coming needs of Spring. Water continues to be lost from the tree. Any creature needing a meal chews and nibbles on the resting buds and twigs. Trees stand alone against all circumstances that the winter season can generate.

What can you do to help your valuable trees? Little things can make your trees more effective and efficient at surviving a long winter. A few small investments now can pay-off in a large way, yielding a healthy and structurally sound tree.

The “Top 10 List” of things you can do to winterize your tree include:

  • Remove or correct structural faults and deadwood that are clearly visible. Try to make small pruning cuts that minimize the exposure of the central heartwood core on branches.
  • Properly prune branches that will touch the ground when loaded with rain and snow. Foliage and branches that are in contact with soil can invite undesirable pests and problems.
  • Remove damaged and declining twigs, branches, and bark. Do not leave pests food and shelter for the winter.
  • Remove any new sprouts that have grown at the tree base, or along stems and branches. Pruning should conserve as many living branches as possible with only a few selective cuts.
  • Spread a thin layer of composted organic mulch to blanket the soil. Cover an area at least as large as the branch spread. Mulch is nature’s of recycling valuable materials, but be careful of pests hitching a ride.
  • Properly wrap new trees that have not developed a corky bark and could be easily damaged. Mechanical injury from the environment, including chewing and rubbing by animals, must be prevented.
  • Aerate soils if they are compacted and poorly drained. It is critical not to damage tree roots in the soil. Saturated and dense soil can suffocate roots.
  • Fertilize with all the essential elements, if they are in short supply within the soil. Be sure to go lightly with nitrogen, especially under large, mature trees and around newly planted trees. It is critical to use slow release nitrogen sources for fall fertilization.
  • Watering may be needed where soils are cool but not frozen, and there has been little precipitation. Winter droughts need treatment with water the same as summer droughts, except it is much easier to over-water in winter.
  • Trees are investments that require a small amount of care. For the sake of your tree’s quality of life and your own, take a few minutes to winterize your tree. Wonderful springs come from well-tended winters.

 

Center Publication Number: 222