By: Jackie Carroll
Maple trees can decline for a variety of reasons. Read on for information about maple tree decline treatment.
Adverse conditions can cause a maple tree so much stress that it no longer thrives. City maples become the victims of air and water pollution, road salts, and construction and landscaping injuries. In the country, trees can be completely defoliated by insects, and putting on a new flush of leaves uses up valuable energy resources. Without energy reserves, trees become vulnerable to decline.
A maple tree depletes its energy reserves when it has to fight off environmental stress, and physical injuries leave trees open to secondary infections. Other causes of maple decline include root breakage and soil compaction from heavy equipment, nutritional imbalance, prolonged drought and vandalism. Almost anything that causes a tree to expend energy to recover can weaken the tree, and if it happens repeatedly the tree goes into decline.
If you suspect maple tree dying, here is a list of symptoms of maple tree decline:
Early intervention can prevent a declining maple tree from dying. Try to identify the cause of the problem and correct it. If your tree is being sprayed with road salts, raise the height of the curb or construct a berm. Divert runoff from roadways away from the tree. Water the tree every week or two in the absence of rain. Make sure the water penetrates to a depth of 12 inches (30 cm.).
Fertilize annually until the tree shows signs of recovery. Use a slow-release fertilizer, or even better, a two-inch (5 cm.) layer of compost. Quick release fertilizers add an excess of chemical salts to the soil.
Prune the tree to remove dead twigs, growth tips and branches. When you remove only part of a branch, cut back to just below a side branch or twig. The side branch will take over as the growth tip. Although it’s alright to remove dead branches any time of year, keep in mind that pruning encourages new growth. When you prune in late summer, the new growth may not have time to harden before cold weather sets in.
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Read more about Maple Trees
Maple decline is a term describing loss of vigor and dieback in forests or urban plantings of maple trees. It is not a disease or a syndrome, nor is it contagious or endemic. Instead, it is a generalized set of symptoms that may be applied to any species of tree suffering a wide range of different stressors.
Norway maple, red maple and sugar maple are the species most commonly affected. The trouble often starts after insect-induced defoliation, which weakens the trees and makes them more susceptible to secondary pathogens. Early signs of decline include small or scorched foliage, and premature fall colors on some of a tree's branches. Later, dead twigs may become visible as signs of distress become evident throughout the crown. As the tree's condition deteriorates, whole branches die. The tree may attempt to compensate for its diminishing crown by producing leafy shoots on its trunk. The defoliation may occur early enough that the tree may produce new leaves in summer that do not harden off before the first frost. Fruiting bodies of bracket fungi may appear on the trunk or in the crown. Eventually, the whole tree dies. The process from first signs of trouble to total death may span anywhere from a few years to several decades.
In urban areas decline is aggravated by soil compaction or disturbance, soil pollution (caused by discarded cigarettes, pet droppings, careless or malicious use of herbicides, and road salt), air pollution and unfavorable moisture conditions. In rural areas, maple decline is often attributed to soil acidification caused by acid rain.  Soils which have developed from nutrient-poor parent materials such as sandstone, quartzite and granite are most sensitive to acidification. Fertile areas often show maple decline where large numbers of livestock such as cattle are allowed to roam in woodlots, as herds or flocks of livestock can compact a soil to a degree which is unfavorable to many of the trees. Carelessness with machinery or taps in sugar bushes is a frequent cause of decline in sugar maple and black maple.
Unusual weather conditions can also lead to maple decline. A classic example occurred across southern Quebec in 1981 when an exceptional February thaw destroyed the snow cover. Later, hard frost penetrated the unprotected ground. The soil was still frozen when the growing season began. Widespread dieback was seen over the remainder of the decade. Subsequent experimentation has verified that trees in Quebec are more likely to show stunted growth and dieback where snow cover is prevented from developing over a winter.
"Decline" is a general term describing the gradual reduction of growth and vigor in a plant. "Dieback" refers to the progressive death of twigs and branches which generally starts at the tips (Figure 1). Trees and shrubs affected by the decline and dieback syndrome may die within a year or two after symptoms first appear or in some cases survive indefinitely. Corrective practices such as proper watering, fertilization, and pruning are not guaranteed solutions in all cases.
Decline and dieback may be caused by many factors (Figures 2 and 3) and is usually progressive over several years. Trees and shrubs of all ages may be affected, although this disease complex is usually associated with plants that have attained some size and maturity.
Symptoms of decline and dieback are often subtle, slow in developing, and usually uniform throughout the crown. A tree or shrub in the dieback stage, however, may have localized symptoms such as apparently healthy twigs and branches adjacent to dead or dying twigs and branches. Dieback usually begins in the top of a plant and progresses downward, but it may start on the lower branches, especially with conifers.
General symptoms of decline and dieback may include pale green or yellow leaves, delayed spring flush of growth, scorching of the leaf margins, small leaves, reduced twig and stem growth, early leaf drop, premature fall coloration, and, as the disease complex worsens, thinning of foliage in the crown, dieback of twigs and branches, and production of suckers on the branches and trunk (Figure 1).
Leaf scorch, a yellow to brown discoloration of the leaf margins and tip, is commonly a part of the decline and dieback syndrome, however, lack of adequate soil moisture, resulting in less water reaching the leaf tips and margins can also cause scorch. Abnormally large seed crops, sometimes associated with decline, is a normal response to certain weather conditions. In some tree species, heavy seed production occurs normally every few years.
Premature fall coloration, delayed spring flush, decrease in twig growth, and early leaf drop are typical symptoms of maple, oak, ash, honeylocust, birch and sweetgum decline and dieback, and the conditions usually become progressively worse each year with the leaves becoming smaller in size and fewer in number.
Figure 1. Dieback of maple caused by chemical injury.
Figure 2. Site factors that can lead to tree decline and dieback (Purdue University photo).
Trees and shrubs are long-lived and over a period of years are subject to attack by a variety of insects and diseases (Figure 3), extremely high or low temperaturesespecially harmful is a rapid drop in temperature following a period of mild weather in the fall or spring(Figure 4), great fluctuations in soil moisture during long-term weather cycles, mechanical damage to roots from construction (Figure 5) or livestock, and numerous other environmental effects (Figure 2).
These stress factors alone or in various combinations can reduce leaf and shoot growth (that is, initiate decline) and lead to dieback, although decline and dieback rarely result from a single stress factor. The combination of human impact on the local environment and natural climatic changes provides a multiplying effect that is more serious than any single factor. Usually a tree or shrub is first injured or damaged by disease (Figure 3), insect attack, or adverse soil or air environmental conditions (Figure 2). The damaged or weakened plant is then subject to attack by one or more secondary organisms or agents. For example, trees and shrubs weakened by drought or neglect are more susceptible to attack by borer-type insects and canker diseases than healthy, vigorous plants. Severe defoliation by leaf-eating insects, diseases, herbicides, hail, or wind at critical times of plant development also may initiate decline and dieback. If a defoliated plant develops new leaves late in the year, and if these leaves are, in turn, killed by an early frost, the plant will be low in food reserves and more subject to winter injury. Weakened trees also are subject to invasion by various fungi. Armillaria root rot, for example, commonly attacks and kills the roots of weakened trees. Many other fungi attack the lower trunk and buttress roots of weakened trees.
Of the many stress factors that can initiate the beginning of decline and dieback, those that weaken or damage the root system are perhaps the most threatening. In most instances of decline and dieback the deterioration of the root system or the blockage of normal root functions occurs before any symptoms are visible in the crown. The root system is especially vulnerable to changes in the soil environment. Soil compaction, changes in the soil drainage pattern, excessive soil moisture (from rain or poor drainage) or lack of water (from prolonged drought), the removal or addition of soil over the root system (Figures 1 and 5), soil compaction, and chemical injury from excess deicing salt, pesticide (Figure 7), or fertilizer all can weaken the root system of trees and shrubs. An excess or deficiency of water, in particular, can lead to permanent root damage. Ash, birch, honeylocust, maple, oak, and sweetgum trees are particularly sensitive to an excess or deficiency of water.
Trees and shrubs planted im-properly or in unfavorable locations will also be stressed by poor root growth and development. Planting trees and shrubs too deeply or incorrectly (Figure 6) or in sites with poor drainage, mineral deficiencies or imbalances, a soil reaction (pH) that is too alkaline, poor soil type, or soil compaction should be avoided. Paved sidewalks, driveways, streets, building foundations, patios, septic tanks, and other obstructions can greatly restrict the growing space for proper root development. If a balance between the crown and root system cannot be maintained, the tree or shrub will be weakened, and decline and dieback may develop a few years after transplanting.
Because so many factors can cause decline and dieback, the primary causes are listed below in the approximate order of general frequency:
1. Poor soil structure and drainage (important when the soil is predominantly clay)
2. Herbicide injury to foliage, roots, or other parts (Figures 3 and 7).
3. Poor transplanting procedure and lack of proper maintenance after transplanting (Figure 6).
4. Construction damagecutting and removal of roots (Figure 5).
5. Significant damage to trunk or major limbs (mechanical injury from lawn mowers, vandalism, vehicles, squirrels and other rodents, livestock, etc.) (Figure 2).
6. Repeated defoliation by insects or diseases, especially such leaf disorders as scorch, anthracnose , rust, and leaf spot or needle blight (Figure 3).
7. An extended drought in combination with high temperatures and strong southerly winds
8. Vascular diseasessuch as Verticillium wilt, oak wilt, or Dutch elm disease (Figure 3).
9. Soil nutrient deficiencies
10 Insect borer injury to the trunk or branches.
11. Canker disease(Figure 3).
12. Excessive soil moisture
13. Extremely low winter temperatures or a rapid change in temperatures (Figure 4).
14. Poorly formed or girdling roots (Figures 2 and 6).
15. Soil compaction from vehicles or heavy construction equipment
16. Fungal root and trunk decays such as Armillaria root rot (Figure 3).
18. Soil fill or removal (Figures 1 and 5).
19. Bacterial wetwood and slime flux
Figure 3. Red maple killed by rapid drop in temp after mild weather in winter.
Figure 4. Many diseases on this "sick" tree could result in decline and dieback. All diseases would not occur on the same tree. Diseases are: 1. Root-lesion nematode 2. root-knot nematode 3. root pruning by nematodes 4. stubby-root nematode injury 5. root rot 6. crown gall 7. fruiting bodies of Armillaria root rot fungus 8. fruiting body of Ganoderma wood and root rot fungus 9. fruiting bodies of Fomes wood rot fungi 10. trunk canker 11. cedar-quince rust on hawthorn 12. cedar-hawthorn rust 13. cedar-apple rust 14. mosaic 15. downy mildew 16. apple scab 17. leaf spot 18. powdery mildew 19. black knot of plum and cherry 20. wetwood (slime flux) 21. fire blight 22. American mistletoe 23. 2, 4-D injury 24. witches' broom 25. fruit rot (apple) 26. overwintering canker of fire blight 27. wilt 28. leaf curl or blister of peach, cherry, or plum 29. leaf blister (oak) 30. sooty blotch and flyspeck of apple 31. leaf blotch 32. shothole 33. anthracnose 34. ringspot 35. sooty mold 36. tar spot 37. leaf scorch 38. apple scab on fruit 39. twig and branch canker (drawing by Lenore Gray).
The exact cause or causes of decline and dieback needs to be identified so that corrective steps may be taken. Accurate diagnosis is often difficult however, especially on older trees. Usually an on-site examination of the diseased tree is required to assess the influence of the environment and to inspect for foliage, branch, trunk, and root problems. Laboratory examination of diseased leaf, twig, or branch specimens may confirm that an infectious disease problem exists (Figure 3). A careful examination of the roots, trunk, and soil conditions can reveal some basic causes for decline. In some cases, a precise diagnosis can be made only by a combination of field and laboratory examinations. It is very important to consider both the site and the past care given the plant. The following steps, as well as the answers to the questions posed, may help to determine the underlying cause or causes of the decline and dieback.
1. Determine the case history of the plant and general area: Has severe and repeated defoliation by insects, disease, or another cause occurred in recent years? Has severe drought or other adverse weather factors affected the plant in recent years? Has the soil been saturated or flooded for extended periods? Has there been construction work near the tree in recent years causing trunk or root damage, soil compaction, or soil deterioration? Has there been soil or root removal? Has there been soil fill? (If unknown, observe whether the normal trunk flare is visible at the soil line. If not, determine the depth to the buttress roots.) Has the water table in the area changed? The use of a soil profile tube is essential in making many of the observations concerning soil problems.
2. Examine nearby vegetation: Is there evidence of injury to surrounding trees, flowers, shrubs, vegetables, fruits, turfgrass, or weeds that would suggest general environmental (Figure 2) or toxic symptoms? Is the tree or shrub's root system subject to salt accumulation from winter ice control along nearby sidewalks or streets? Is there a toxic sewage disposal field or gas line near the root system that may be leaking?
3. Consider chemical treatments to or near the tree or shrub: What is the history of pesticide use, particularly herbicides or "weed and feed" combinations? Was a soil sterilant or biocide used in a nearby gravel driveway or sidewalk?
4. Examine leaves for foliar diseases and insects.
5. Eliminate the possibility of a vascular disease, that is, oak wilt, Dutch elm disease, Verticillium wilt, or mimosa wilt, by considering the pattern of symptom development and by examining for internal sapwood discoloration.
6. Have a professional arborist determine the year(s) or period(s) of tree stress by examining the amount of twig growth and the width of growth rings in the wood. Also have the arborist check the pattern of annual stem elongation to determine if and when growth has slowed or stopped. (The arborist will examine the growth of annual rings over the last several years with an increment hammer or borer.)
7. Examine branches and trunk for extensive cankers that may be the cause of damage or that may be associated with an environmental or other stress.
8. Examine trunks and buttress roots for evidence of injury, for example, a sunscald, fire, mower, frost crack, or lightning injury. Look for loose bark (tap the bark and exposed roots and listen for a telltale hollow sound). Check for mushrooms or conks of wood and root decay fungi. Fungal fruiting structures are most common in spring and fall following periods of wet weather.
9. Carefully excavate the buttress roots for evidence of fungal decay, poorly formed roots, girdling roots or twine, and similar problems.
Figure 5. 2, 4-D injury to redbud leaves.
Once the symptoms of decline or dieback are evident, it is difficult to stop or reverse the progress of disease. The key to control is early detection and prevention. The following measures will aid in maintaining the health of trees and shrubs.
For further information concerning diseases of woody ornamentals, contact Nancy R. Pataky, Extension Specialist and Director of the Plant Disease Clinic, Department of Crop Sciences, University of Illinois at Urbana.
University of Illinois Extension provides equal opportunities in programs and employment.
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Maple decline (i.e. maple blight, maple dieback) has periodically caused significant losses of sugar maple in northern hardwood forests. The first major outbreak of maple decline was reported in northeastern Wisconsin and upper Michigan in the late 1950's. The disease reappeared in the same general area during the late 1970's and early 1980's.
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Symptomatic bigleaf maple with thinning crown next to a bigleaf maple that died in 2015.
Chlorotic tipped and small leaves of bigleaf maple next to healthy, large green bigleaf maples leaves.
Cause Unknown. Forest pathologists have been investigating a new decline and dieback of bigleaf maple that emerged in 2010. The problem is widespread throughout western Washington and Oregon and may extend into California. Many pathogens have been ruled out as the primary cause (but may be involved in secondary symptoms) including Armillaria , various oomycetes, Nectria cankers, stem decay fungi such as Ganoderma , and Verticillium . Testing for the bacterium Xylella fastidiosa has been negative. Abiotic factors, such as drought, are possible but none has emerged as the definitive cause.
Leafhoppers may be heavily involved with Empoasca elongate as the primary insect. This is a native leafhopper on bigleaf maple and is a relative of the potato leafhopper, Empoasca fabae , which causes a great deal of damage to field crops in the Eastern US. The saliva of the potato leafhopper mechanically injures host plant cells that transport water and nutrients, causing "hopperburn." E. elongata appears to be causing similar damage in bigleaf maples with water stress playing an important role in exacerbating the damage.
Symptoms Crown, branch, and entire tree dieback with clumps of shrunken leaves in the canopy and heavy seed crops. Trees of many ages and sizes have died from this disease. Additional symptoms may include leaves with yellow edges and red-to-brown tips typical of leaf scorch.
Cultural control Maintain trees as best you can with minimal care and infrequent deep waterings during the summer months while forest pathologist scratch their heads.
References Betzen, J. J. 2018. Bigleaf Maple Decline in Western Washington (Doctoral dissertation).
The branches on one side of my sugar maple have been dying this summer. I found insects on the leaves of the tree last week and wonder if they are killing the branches. How should I treat my tree?
— Jeff Nichols, Highland Park
It is best for us to have a sample in hand and more information about the site to accurately identify the pest on your maple and suggest what treatment steps to take. Based on the photo you provided, the insect appears to be either cottony maple scale or woolly aphid. Both of these are minor pests and would not cause limb loss. Generally, natural predators build up and adequately control these minor pests without any intervention on your part.
Your description of limbs dying on one side of your maple suggests a more serious problem linked to the tree's root system. There could be a girdling root that is tightly wrapped around the trunk below the soil line. Stem girdling roots choke off the flow of water and nutrients between the roots and branches, and they prevent food produced in the leaves from reaching the roots. Symptoms of stem girdling roots include excessive dieback and/or thin appearance of the crown, dead branches, unusually small leaves, damage to one or two branches and no trunk taper at ground level.
The dying branches could be caused by a girdling root. Work with an arborist to use an air spade to remove the soil around the base of the tree to look for a girdling root. You may be able to correct this issue by cutting the girdling root during the dormant season, depending on the size of the root involved. In some situations, the root could be too large to correct.
Another potential cause of dying branches: phytophthora root rot. This widespread soil pathogen causes problems among landscape plants. Funguslike organisms grow in the plant and affect the movement of water and nutrients, causing general decline that can lead to plant death. Phytophthora diseases are most common in soils that are poorly drained or overwatered. When soil moisture and temperature conditions bolster this disease, it can worsen rapidly. Look for dark, water-soaked spots on the trunk and/or cankers as additional signs of this disease.
Similarly, verticillium wilt is caused by a soil fungus and affects the movement of water through a plant. One or more branches — usually on one side of a tree — will show symptoms that can include wilting, yellowing leaves and leaves with margins that turn brown and appear scorched. There can be a gradual decline that includes dead twigs and branches. Scrape the bark on an affected branch, and look for streaking as a sign of this disease. There is no chemical control for verticillium wilt, but your tree may grow out of it. Disinfect your pruning implements after snipping dead branches, as verticillium can be spread by tools.
If you have plant or gardening questions, contact the Chicago Botanic Garden's Plant Information Service at 847-835-0972.
Tim Johnson is director of horticulture for the Chicago Botanic Garden in Glencoe.
การแทรกแซงในช่วงต้นสามารถป้องกันไม่ให้ต้นเมเปิ้ลที่ร่วงโรยตาย พยายามระบุสาเหตุของปัญหาและแก้ไข หากต้นไม้ของคุณถูกฉีดพ่นด้วยเกลือถนนให้ยกระดับความสูงของขอบถนนหรือสร้างแนวกั้น เบี่ยงทางไหลออกจากถนนให้ห่างจากต้นไม้ รดน้ำต้นไม้ทุกสัปดาห์หรือสองสัปดาห์ในช่วงที่ไม่มีฝน ตรวจสอบให้แน่ใจว่าน้ำทะลุได้ลึก 12 นิ้ว (30 ซม.)
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