Common Symptoms and Possible Causes

This webpage is adapted from a chart featured on pages 579-591 in the book Arboriculture: Integrated Management of Landscape Trees, Shrubs, and Vines 3rd ed by Richard W. Harris, James R. Clark, and Nelda P. Matheny; published in 1999 by Prentice Hall, Upper Saddle River, New Jersey 07458.

Symptoms

LEAVES

SHOOTS

BRANCHES/TRUNK

ROOTS

 

Symptom Possible Cause Pattern of Symptoms How to Diagnose
LEAVESLink to top of page.
WiltingLink to top of page.
  A. Water Stress
  1. Loss of roots
  a. Infectious disease (e.g. Phytophthora root rot, Phymatotrichum root rot) Overall, gradual decline affecting only one or a few susceptible species. Symptoms may appear suddenly during hot weather. Inspect roots for discoloration, lesions, death. Send samples to disease testing laboratory.
  b. Mechanical injury (e.g. trenching through root system) Sudden symptoms of all plants in affected area. Symptoms may be delayed until hot weather. Determine history of site change; inspect for injury.
  c. Poor soil aeration
  i. Flooding, poor drainage, high water table, over-irrigation Gradual development of symptoms affecting entire planting. Some species may be more sensitive than others. Use soil probe or shovel to check moisture and color of soil. Blue or gray color and foul smell indicate anaerobic conditions.
  ii. Fill soil over roots, compacted soil Gradual development of symptoms affecting entire planting. Some species may be more sensitive than others. Excavate at base of tree to determine depth of original trunk flare.
  d. Insect damage (e.g. weevils and root-feeding beetles) Overall, sudden symptoms affecting one or more plants within a species. Inspect root area for damage and presence of insect. Early sign is leaf damage (notching) by feeding of adult.
  2. Water movement from roots to top interrupted.
  a. Disease affecting xylem (e.g. verticillum wilt; Dutch elm disease, oak wilt) Symptoms usually in one branch or section of canopy and affecting only one plant or species Symptoms may appear suddenly during hot weather. Determine susceptibility of species. Cut into twig to look for discoloration in xylem. Submit samples to laboratory
  b. Insects feeding on xylem (e.g. bark beetles, borers) Damage usually on single branch or scattered through crown, unless trunk affected, and on one or more plants within a species. Look for borer exit holes, dead bark.
  c. Mechanical damage to xylem Entire or portion of plant may be affected. Not restricted to one species. Symptoms may develop gradually or suddenly depending on extent of damage and transpirational demand. Inspect plant for damage to bark. Check for girdling by staking wire.
  d. Feeding by small mammals Entire plant usually affected. May not be restricted to one species. Symptoms may develop gradually or suddenly depending on extent of damage and transpirational demand. Look for teeth marks at site of injury, especially where small animals can hide under foliage.
  3. Not enough water available for plant Entire planting usually affected, especially drought-sensitive species. Symptoms develop suddenly. Plants with greatest sun and wind exposure show most severe symptoms. Use soil probe to check soil moisture.
  a. Under-irrigation See above
  b. Water not penetrating into soil See above
  i. Water running off slope. See above; soil may be wet at toe of slope. See above
  ii. Surface hydrophobic or compacted. See above; puddles may be present in low areas. See above
  c. Insufficient water holding capacity in root area See above Test water penetration through surface layer.
  i. Shallow soil See above Investigate soil profile.
  ii. Very sandy soil See above Determine soil texture.
  4. Exceptionally high demand for water (e.g. high temperature, wind, dry air) See above. Plants usually recover overnight. Determine weather conditions.
Leaf NecrosisLink to top of page.
MarginalLink to top of page.
  A. Water stress
See wilt for causes		 See wilt See wilt
  B. Toxicity
  1. High soil salinity Overall, gradual development of symptoms of entire planting. Necrosis most severe on older leaves. Tolerant species may not show damage. If due to deicing salts, damage more severe onside of plant facing road. Test soil for salinity, Cl. Determine history of salt application for snow and ice control.
  2. High boron content Overall, gradual development of symptoms of entire planting. Necrosis most severe on older leaves. Tolerant species may not show damage. May appear as small necrotic spots along margin rather than entire leaf. Test soil for boron.
  3. Herbicide (e.g. diuron, atrazine, dalapon, borates) Sudden, overall symptoms affecting entire planting. Determine possible herbicide category, and test.
  C. Severe iron deficiency       Overall, gradual development of symptoms of entire planting. Symptoms most severe on older leaves. Tolerant species may not show damage. Test soil for pH, carbonates; test foliage for Fe.
  D. Infectious disease (e.g. bacterial scorch) May be sudden or gradual symptom development. Confined to one species in planting. Difficult to diagnose. Xylem-inhibiting bacteria cannot be isolated, but they can be detected with an electron microscope. Determine sensitivity of plant to organism. Limited to regions of moderate winter temperature.
BlotchLink to top of page.
  A. Water stress
See wilt for causes		 See wilt See wilt
  B. Too much sun for species Sudden symptoms on outside of canopy affecting sun-sensitive plants. May start with yellowing on tips and margins of leaves. Determine exposure, reflected heat and plant tolerances. More severe when coupled with low soil moisture. May appear following pruning, removal of adjacent plant, increased exposure.
  C. Infectious disease(e.g. anthracnose) May be sudden or gradual symptom development. Confined to susceptible species in planting. Examine leaves for signs of disease organism; submit samples to laboratory. Determine if time of year and weather are favorable for disease.
SpotLink to top of page.
  A. Infectious disease (e.g. bacterial leaf spot, black spot) Sudden symptoms on one plant or species. Examine leaves for signs of disease organism;submit samples to laboratory.
  B. Insect damage (e.g. sycamore scale) Sudden symptoms on one plant or species. Examine leaves for signs of insect; submit samples to laboratory.
  C. Herbicide (e.g. paraquat,bentazon, diphenyl-ethers,oxadiazon, diquat, fluazifop,cyclohexenone) Sudden symptoms with greatest damage on outer leaves present at the time of exposure. Spots usually uniform in size, color and distribution,with sharp margin. Determine what herbicides have been used nearby. Submit samples to laboratory for testing.
Interveinal necrosisLink to top of page.
  A. Air pollution Sudden or gradual symptom development depending on level and type of pollutants. Affect entire planting. Determine recent air quality and species sensitivity.
  B. Herbicide Sudden symptom development affecting entire planting Determine what herbicides have been used. Submit samples to laboratory for testing.
  C. Severe manganese deficiency Gradual symptoms development on old and new foliage. Symptoms most severe on species sensitive to alkaline soil. Collect soil sample and test for pH, calcium carbonate Collect leaf samples and submit to laboratory for Mn testing.
Entire LeafLink to top of page.
  A. Water stress (see wilt for causes) See wilt See wilt
  B. Infectious disease (e.g.anthracnose) May be sudden or gradual symptom development on all or a portion of the plant. Confined to one species in planting. Examine leaves for signs of disease organism; submit samples to laboratory. Determine if time of year and weather is favorable for disease.
  C. Herbicide (e.g. weed oil, diquat, paraquat, oxyfluorfen) Sudden symptom development affecting entire planting. Determine what chemicals have been applied. Collect soil and/or leaf samples for testing.
  D. Frost Sudden symptom development affecting entire planting. Determine recent temperatures and plant hardiness.
  E. Winter injury Common in evergreens in late winter/early spring following winds. Most severe on side of plant exposed to wind. Determine if soil is frozen.

Leaf ChlorosisLink to top of page.

 Note: Variation in leaf color is often a normal characteristic of a species or cultivar.
GeneralLink to top of page.
  A. Lack of nitrogen Gradual symptoms development, affecting entire planting. Symptoms most severe on older foliage first. Determine when fertilizer last applied. Test foliage for nitrogen concentration.
  B. Damaged root system
  1. Saturated soil. Overall, gradual development of symptoms affecting entire planting. Use soil probe or shovel to check moisture and color of soil. Blue or gray color and foul smell indicate anaerobic conditions.
  2. Fill soil over roots. Gradual development of symptoms affecting entire planting. Excavate at base of tree to determine depth to original trunk flare.
  3. Mechanical damage A portion or the entire plant may be affected. Chlorosis symptoms usually gradual, but plant may wilt suddenly during hot weather. Determine history of site change; inspect for injury.
  4. Infectious disease (e.g.Phytophthora root rot), nematodes Overall, gradual decline affecting only one or a few susceptible species. Or, symptoms may appear suddenly during hot weather. Inspect roots for discoloration, lesions, death. Evaluate soil moisture and drainage conditions. Send samples to disease testing laboratory.
  C. Moderate soil salinity Overall gradual symptom development affecting salt sensitive plants in area. Collect soil sample and analyze for salinity
  D. Girdled trunk or roots
  1. Staking ties embedded in trunk Gradual symptoms development on individual plant. Examine staking ties for damage to trunk
  2. Sunburned trunk Damage only to portions of bark exposed to afternoon sun. Most severe on thin-barked trees. Examine sides of trunk exposed to afternoon sun for dead and damaged bark. Damage worse when soil moisture low.
  3. Infectious disease affecting phloem or roots (e.g.microplasma-like organisms) Symptoms may appear in part or all of canopy and affect only one plant or species. Symptoms may appear suddenly during hot weather. Examine tissue below bark at root crown and trunk for discoloration, signs of organism. Submit samples to laboratory MLOs causing yellows diseases cannot be cultured, but are identified in electron microscopy.
  4. Mechanical damage       Entire plant usually affected. Not restricted to one species. Symptoms may develop gradually or suddenly depending on extent of damage and transpirational demand. Check root collar, trunk and major branches for wounds.
  E. Gas injury (leaks, landfill) Overall, gradual yellowing of all plantings. Some species are more sensitive than others. Symptoms progress to slow growth and death. Check for foul odor and blue-gray or black color in soil. Test soil atmosphere for gas. Cut into root and trunk tissue to check for blue or brown streaks in wood.
InterveinalLink to top of page.
  A. Micronutrient deficiency
  1. Iron (Fe) deficiency           Overall, gradual development of symptoms of entire planting. Symptoms most severe on young growth. New growth may be bleached,and in severe cases develop necrotic area. Species tolerant of alkaline soil may not show damage. Collect soil sample and test for pH, calcium carbonate. Collect leaf samples and submit to laboratory. Symptoms may be temporary if soils are cold and/or wet.
  2. Manganese (MN) deficiency           Overall, gradual development of symptoms of entire planting. Band of green tissue around veins wider than Fe deficiency. Symptoms on both old and new growth. Leaves may develop necrotic spots. Species tolerant of alkaline soil may not show symptoms. Collect soil sample and test for pH, calcium carbonate. Collect leaf samples and submit to laboratory to test for MN concentration.
  B. Parasitic root disease (e.g.Phytophthora root rot, nematodes) Symptoms may look like micronutrient deficiency because diseased roots cannot absorb elements, Usually confined to one or a few susceptible species. Examine roots for discolored, dead tips. Evaluate soil moisture and drainage characteristics. Submit samples to laboratory for testing.
  C. Herbicide (e.g. triazines,atrazine, siinazine) Greatest chlorosis along tips, margins and veins on leaves, beginning in older foliage. Entire planting affected. These materials are soil-applied. Collect soil samples and submit to laboratory for testing.

Mottling/MosaicLink to top of page.
  A. Zinc deficiency Young foliage develops symptoms first. Leaves may be abnormally small and necrotic, with short intermodes (rosette). More than one species may show symptoms. Collect soil sample and test for pH, calcium carbonate. Collect leaf samples and submit to laboratory to test for Zn concentration.
  B. Virus (e.g. elm mosaic virus, poplar mosaic virus) Gradual symptoms develop on one plant or one species. Collect samples and submit to laboratory for testing. Usually diagnosis on basis of symptoms and host susceptibility.
  C. Herbicide (e.g. uracils, bromacil, terbacil) Sudden symptoms on entire planting exposed to chemical. Collect soil samples and submit to laboratory for testing.
Vein ClearingLink to top of page.
  A. Virus (e.g. elm mosaic virus, yellow net disease) Gradual symptoms develop on one plant or one species. May affect a portion or all of plant. Collect samples and submit lo laboratory for testing. Usually diagnosis on basis of symptoms and host susceptibility.
  B. Herbicide (e.g. substitute dureas, diuron, monuron,neburon) Sudden symptoms development on entire planting. Interveinal tissue remains green. May affect a portion or all of plant. Determine what chemicals have been applied. Collect samples and submit to laboratory for testing.
StipplingLink to top of page.
  A. Mites, insect (e.g. aphids, leafhoppers, plant bugs, thrips) Sudden symptom development on individual plant, or susceptible species. Symptoms usually worse on older foliage. Inspect plant for signs of insects. Look for varnish spots on bottom of leaf.
  B. Air pollution Sudden or gradual symptom development depending on level and type of pollutants. Affects entire planting. Determine recent air quality and species sensitivity.
SilveringLink to top of page.
  A. Mites, insects (e.g. thrips) Sudden symptom development on individual plant,or susceptible species. Symptoms usually worse on older foliage. Inspect plant for signs of insects. Look for varnish spots on bottom of leaf.
  B. Air pollution Sudden or gradual symptom development depending on level and type of pollutants. Affects entire planting. Determine recent air quality and species sensitivity.
BleachingLink to top of page.
  A. Herbicide (e.g. amitrole, norflurazon, clomazone) Sudden symptoms on new leaves, particularly at the tips. Entire planting exposed to chemical affected. Determine what chemicals have been applied. Collect samples and submit to laboratory for testing.
  B. Iron deficiency Symptoms most severe on young growth. Necrotic areas may develop. Species tolerant of alkaline soil may not show damage. Collect soil sample and test for pH. calcium carbonate Collect leaf samples and submit to laboratory. Symptoms may be temporary if soils are cold and/or wet.
  C. Parasitic root disease (e.g.Phytophthora root rot) Symptoms may look like micronutrient deficiency because diseased roots can not absorb elements. Usually confined to one or a few susceptible species. Examine roots for discolored, dead tips. Evaluate soil moisture and drainage characteristics. Submit samples to laboratory for testing.
Ragged LeavesLink to top of page.
  A. Insects (e.g. beetles, caterpillars) Sudden symptoms on one or more plants within a species. Inspect plant for signs of insects.
  B. Weather damage (e.g. wind, hail) Sudden symptoms on all plants exposed to damaging agent. Determine recent weather conditions.
Holes in LeavesLink to top of page.
  A. Insects (e.g. beetles, caterpillars) Sudden symptoms on one or more plants within a species. Inspect plant for signs of insects.
  B. Infectious disease (e.g. X-disease [mycoplasma], shot hole[fungus]) Sudden symptoms on one or more plants within a species. Hole created when necrotic area falls out. Collect samples and submit to laboratory for testing. Determine if time of year and weather are favorable to disease. MLOs cannot be isolated in laboratory tests, but can be identified by electron microscopy.
Malformed LeavesLink to top of page.
  A. Infectious disease (e.g. peachleaf curl, Exobasidium) Sudden symptoms on one or more plants with in a species. Collect samples and submit to laboratory for testing. Determine if time of year and weather is favorable to disease.
  B. Insects (e.g. aphids, leaf rollers, tiers) Sudden symptoms on one or more plants within a species Inspect plant for signs of insects.
  C. Herbicide (e.g. glyphosate, sulfonylureas, imidazolinones) New growth develops with deformation symptoms as well as tip chlorosis and dieback. All plants within treated area affected. Determine what chemicals have been applied. Glyphosate injury may not be seen until spring following fall application. For soil applied chemicals, collect soil samples and submit to laboratory for testing.
Growth on LeavesLink to top of page.
  A. Insects (e.g. blister mite, gall wasps) Sudden symptoms on one or more plants within a species. Inspect plant for signs of insects.
Mines in LeavesLink to top of page.
  A. Insects (e.g. sawflies, leafminers) Sudden symptoms on one or more plants within a species. Inspect plant for signs of insects.

Sudden Leaf Drop Link to top of page.

 Note: Some broad-leaved evergreens normally have heavy drop of oldest leaves at various times of year.
  A. Severe water stress See wilt for causes See wilt
  B. Infectious disease (e.g.Entomosporium) Sudden symptoms on one or more plants within a species Collect samples and submit to laboratory for testing Determine if time of year and weather are favorable to disease.
  C. Herbicide (e.g. bromacil)       Sudden symptoms on entire planting with treate area. Defoliation may be preceded by marginal necrosis. Older foliage affected first. Determine what chemicals have been applied. Collect soil samples and submit to laboratory for testing.
Delayed foliationLink to top of page.
  A. Inadequate chilling Foliage or flowers do not emerge in temperate deciduous plants requiring chilling Determine if winter temperatures have been below 7░C (45░F) for an adequate length of time.
  B. Insects (e.g. aphids) Lack of leaf expansion on one plant or species. Check shoot tips for heavy insect feeding.
  C. Infectious disease(e.g. anthracnose) Lack of leaf expansion on one species. Leaves at edges of canopy may expand, but lower and interior foliage does not. Usually associated with rain during normal leaf expansion. Examine shoot tips for signs and symptoms of disease.
SHOOTSLink to top of page.
Wilting and/or DiebackLink to top of page.
  A. Water stress See Leaves-wilting-water stress See Leaves-wilting-water stress
  B. Insect damage
  1. Wood feeders (e.g. borers, twig girdlers) Sudden flagging scattered throughout canopy on one or more plants within a species, Cut into twigs at base of dieback to inspect for larvae, mining tracks.
  2. Sap feeders (e.g. aphids, wooly aphids) Gradual flagging scattered through canopy on one or more plants within a species. Inspect twigs for signs of insects.
  C. Infectious disease (e.g.bacterial blight, verticillium wilt) Sudden flagging scattered throughout canopy on one or more plants within a species. Inspect tissue for signs of disease organism, sunken or discolored bark, cankers, bleeding. Send samples to laboratory.
  D. Frost Sudden, overall symptoms on all cold-sensitive species in planting. Determine recent temperatures.
DistortionLink to top of page.
  A. Insect (e.g. pod gall midge, aphid) Scattered damage throughout canopy of one or more plants within a species. Inspect tissue for signs of insects.
  B. Infectious disease Scattered damage throughout canopy of one or more plants within a species. Inspect tissue for signs of disease organism; submit sample to laboratory for testing.
  C. Virus Scattered damage throughout canopy of one or more plants within a species. Submit sample to laboratory for testing.
  D. Herbicide (e.g. thiocarbamates, 2,4-D, dicamba, glyphosate, dalapon) Symptoms appear on new growth throughout planting. Thiocarbamates are applied to soil; collect samples and send to laboratory for testing. 2,4-D and dicamba may be in fertilizers and weed control mixtures applied to turf.
  E. Fasciation Symptoms usually on only one or a few branches, and only one plant. Abnormal flattening and curling of stem due to mutation in cell.
Witches' BroomLink to top of page.
 Note: Witches' broom is an abnormal clustering of branches caused by a disease organism.
  A. Infectious disease - Fungi (e.g. powdery mildew), microplasma-like organisms (e.g. bunch disease) Scattered damage throughout canopy of one or more plants within a species. Examine plants for signs of disease organism. Collect samples and submit to laboratory for testing. MLOs cannot be isolated in laboratory tests, but can be identified by electron microscopy.
  B. Insects (e.g. mites) Scattered damage throughout canopy of one or more plants within a species. Inspect tissue for signs of insects.
  C. Mistletoe Scattered damage throughout canopy of one or more plants within a species. Inspect canopy for foliage of parasitic plant.
  D. Cell mutation Symptoms usually on only one or a few branches, and only one plant. Eliminate other causes.
  E. Herbicide (e.g. glyphosate) New growth develops with deformation of young leaves and proliferation of new buds without elongation. All plants within treated area affected. Determine what chemicals have been applied. Glyphosate injury may not be seen until spring following fall application.
BRANCHES, TRUNK Link to top of page.
Sunken, discolored barkLink to top of page.
  A. Infectious disease (e.g. fireblight, cypress canker) Isolated areas on individual plant or plants within a susceptible species. Symptoms generally develop gradually. Portion beyond canker may wilt, show chlorosis or necrosis. Cut into bark to determine condition of phloem and sapwood. Look for signs of organism. Submit samples to laboratory for testing.
  B. Sunburn Located on portions of trunk exposed to afternoon sun. Cut into bark to determine condition of phloem and sapwood.
Woundwood formationLink to top of page.
  A. Mechanical damage Isolated area at point of impact or injury. Gradual development. Inspect plant for damage.
  B. Canker disease (e.g. Nectriacanker, Ceratocystis canker) Isolated areas on individual plant or plants within a susceptible species. Woundwood area enlarges annually. Portion beyond canker may wilt, show chlorosis or necrosis. Cut into bark to determine condition of phloem and sapwood. Look for signs of organism. Submit samples to laboratory for testing.
  C. Sunburn of bark Located on portions of trunk exposed to afternoon sun. Cut into bark to determine condition of phloem and sapwood.
  D. Repeated insect invasion (e.g. sycamore borer) Multiple, isolated areas on individual plant or plants within a susceptible species. May be bleeding at entrance or exit holes. Look for frass, borer exit holes.
  E. Freezing temperatures After repeated splitting, woundwood ridges form along edges of crack and wood decay may begin. Trees 150 to 450 mm (6 to 18 in.) in diameter are more likely to be affected than smaller or larger trees. Determine winter low temperatures and examine tree for associated defects.
GallsLink to top of page.
  A. Infectious disease (e.g. crown gall, pine gall rust) Isolated areas on individual plant or plants within a susceptible species. Portion beyond gall may decline. Identify organism based on appearance of gall and susceptibility of host.
  B. Insect (e.g. oak apple gall) Affects one plant or more plants within a species. Examine for signs of insect. Cut into galled area to look for insect.
  C. Mistletoe Scattered damage throughout canopy of one or more plants within a species. Look for green foliage of mistletoe.
  D. Bud masses, swirling grain(burls) Affects one plant or more plants within a species. Determine if burls or lignotubers are common for the species.

Bark Falling Off Link to top of page.

Note: Peeling and cracking bark as it matures is a normal characteristic of some trees.
  A. Insect (e.g., borers, bark beetles)           Gradual development of symptoms as infestation levels increase. May be more severe on portions of bark exposed to afternoon sun, and in drought stressed plants. Usually affecting only one species. Look for borer exit holes, frass, bleeding around holes Examine under bark for larvae.
  B. Infectious disease (e.g. pineblister rust, Hypoxylon canker, Hispidus canker) Gradual development of symptoms on one or more plants in a species. Portion beyond infection may decline and die. Examine area for fruiting bodies of fungus, submit samples to laboratory.
  C. Sunburn Located on portions of trunk exposed to afternoon sun. Cut into bark to determine condition of phloem and sapwood.
  D. Sprinkler water hitting trunk Damaged area corresponds to sprinkler pattern. Most common on trees with thick corky bark and palms. Determine sprinkler pattern.
  E. Low vigor Gradual, overall decline in plant health. Tree decline may lead to bark exfoliation.
  F. Lightning injury       Occurs most commonly on lone, tall frees,windward edges of stands, and dominant frees in stands. Damaged branches may die. Look for strip of bark removed from top to bottom of tree, with a rough groove that follows the grain of wood.

Bleeding. GummingLink to top of page.

 Note: Exudation of sap is a normal characteristic in some species.
  A. Bacterial wetwood Gradual development of symptoms in susceptible species. Occasionally foliage in the tops of trees wilt and branches may die back. Usually unimportant except for disfiguring appearance. When liquid exposed to air, becomes foamy from growth of yeast. When bore into tree with wetwood, liquid may be forcefully expelled.
  B. Infectious disease (e.g.Coryneium blight, blister rust) Gradual development of symptoms in susceptible species. Portion of plant beyond canker may decline and die. Examine area for fruiting bodies of fungus, submit samples to laboratory.
  C. Insect (e.g. sequoia pitch moth,borers, bark beetles) Gradual development of symptoms in susceptible species. Portion of plant beyond infestation may decline and die, depending on extent of feeding injury. Look for borer exit holes, frass. Examine under bark for larvae.
  D. Water stress See wilt See wilt; common on stone fruits.
Holes in barkLink to top of page.
  A. Insect (e.g. borers, bark beetles) Gradual development of symptoms in susceptible species. Portion of plant beyond infestation may decline and die, depending on extent of feeding injury. Remove section of bark at borer exit hole to look for larvae and their tunnels.
  B. Sapsucker Uniformly drilled holes in horizontal bands around trunk or branch. Where injury is severe, tree may be girdled and portion beyond decline. Pattern of damage is diagnostic.
SwellingLink to top of page.
  A. Graft union In grafted trees, diameter of stock is much larger than that of scion at the graft union. Not considered a problem.
  B. Girdling
  1. Staking tie left too long Swelling of trunk above tie. Examine staking ties for damage to trunk.
  2. Girdling root Bulge in trunk above girdling root. Excavate to examine root crown and determine if girdling root present.
  C. Decay fungi (e.g. Ganoderma,Fomes) Very slow development over many years. Drill or bore into trunk to evaluate presence of decay.
Splitting, CrackingLink to top of page.
  A. Herbicide (e.g. phenoxycompounds) Susceptible woody plants exposed to chemical. Usually accompanied by foliar and shoot distortion. Determine what chemicals have been applied. 2,4-D and dicamba may be in fertilizers and weed control mixtures applied to turf.
  B. Freezing temperatures            Longitudinal cracks usually associated with wounds and branch stubs. After repeated splitting, woundwood ridges form along edges of crack and wood decay may begin. Trees 150 to 450 mm (6 to 18 in.) in diameter are more likely to be affected than smaller or larger trees. Determine winter low temperatures and examine tree for associated defects.
  C. Growth cracks Occur in areas of vigorous growth, especially in species with thick bark. Crack is in corky bark and does not penetrate to inner bark and wood. Indication of vigorous growth.
  D. Mechanical failure Most common on individual branches or trunks with excessive weight, especially when exposed to strong wind, ice, snow or rain.

Mushrooms, Conks
Attached to tree.Link to top of page.
  E. Signs of decay fungi attached to tree (e.g. Armillaria, Ganoderma, Phellinus) Usually on older plants that have been wounded in the past. Identify species of fungi.
ROOTSLink to top of page.
ShriveledLink to top of page.
  A. Water stress See wilt See wilt
  B. High soil salinity Overall, gradual development of symptoms of entire planting. Necrosis most severe on older leaves and leaf margins. Tolerant species may not show damage. Test soil for salinity; Cl. Determine history of salt application for snow or ice control.
  C. Herbicides (e.g. dinitroanilines, amides, thiocarbamates) Overall, gradual development of symptoms of entire treated area. Plants usually are stunted, may show general or interveinal chlorosis. Determine herbicide category and test in laboratory.
DiscoloredLink to top of page.
  A. Infectious disease (e.g. Phytophthora root rot, Pythium) Overall, gradual decline affecting only one or a few susceptible species. Or, symptoms may appear suddenly during hot weather. Inspect roots for discoloration, lesions, death. Send samples to disease testing laboratory.
  B. Poor soil aeration
  1. Flooding, poor drainage, high water table, over irrigation Gradual development of symptoms affecting entire planting. Some species may be more sensitive than others. Use soil probe or shovel to check moisture and color of soil. Blue or gray color and foul smell indicate anaerobic conditions.
  2. Fill soil over roots, compacted soil Gradual development of symptoms affecting entire planting. Some species may be more sensitive than others. Excavate at base of tree to determine depth to original trunk flare.
DistortedLink to top of page.
  A. Herbicide (e.g. trifluralin, oryzalin) Overall, gradual development of symptoms of entire treated area. Plants usually are stunted,may show general or interveinal chlorosis. Roots are swollen, club-shaped. Derermine what chemicals have been applied; collect soil sample and submit to laboratory.
  B. Nematodes             Overall, gradual development of symptoms of one or more plants of susceptible species. Plants usually are stunted, may show general or interveinal chlorosis. Pratylenchus sp. cause dark lesions on roots. Trichodorus cause root tips to thicken, become corky. Collect root samples and submit to laboratory for testing.
  C. Mycorrhizae Small roots bleed, beaded or brainlike in shape and plant. Beneficial; symbiotic relationship between fungus
  D. Insect (e.g. root aphid) Overall, gradual decline affecting only one or a few susceptible species. Or, plant may wilt suddenly during hot weather. Root collar and roots develop abnormal swellings. Examine roots for signs of insects.
GallsLink to top of page.
  A. Nitrogen-fixing bacteria Roots covered with small gall-like nodules. Beneficial; symbiotic relationship between bacteria and plant. Cut into nodule. Active nodules are pink in color.
  B. Nematodes (e.g. root-knot nematodes) Overall, gradual development of symptoms of one or more plants of susceptible species. Plants usually are stunted, may show general or interveinal chlorosis. Roots covered with small to medium-sized galls. Cut into root knot to look for female body. Submit root samples to laboratory for testing.
  C. Insect (e.g. wooly apple aphid) Overall, gradual decline affecting only one or a few susceptible species. Or, plant may wilt suddenly during hot weather. Root collar and roots develop corky galls, often with white cottony wax from insect visible. Inspect affected tissue for signs of insect.
Deterioration of TissueLink to top of page.
  A. Wood decay (e.g. Armillaria root rot, laminated root rot) Overall, gradual decline affecting only one or a few susceptible species. Or, plant may wilt suddenly during hot weather. Tree may fall over. Excavate soil to examine woody roots.