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7 Colour plates: examples of ill-health in trees

The colour plates give visual examples of different types of symptoms and damage associated with tree health problems. They are organized according to the classification of symptoms described in Table 3, Chapter 5. The captions describe the problem and give the name of the pest or other factors responsible for the symptoms. The host name and site are included in the caption. Colour plates can be searched by tree host and health problem in Annex 3.

Colour plates

Altered growth or development







General death

Plate 7: BLIGHT

Plate 8: DIEBACK


Localized death


Plates 11A, 11B: CANKERS


Physical evidence





Altered growth or development
Colour changes in crown

The examples in Plates 1A and 1B illustrate a wide variety of causes. Nutrient disorders and “site factors” are often said to be the cause of poor health, as determined by the appearance of crowns. But also look out for symptoms such as smaller leaves [1.2] and unusual patterns of leaf discolouration [1.5].

1.1 Unknown cause, possibly genetic abnormality. No evidence of pest attack. Only one tree affected. Azadirachta indica, Niger.

1.2 Suspected peach yellows (left), phytoplasma disease. Leaves are smaller than on healthy trees. Prunus persica, Camargo, Bolivia.

1.3 Fungal root disease is the suspected cause of these foliar symptoms and decline. Austrocedrus chilensis , Bariloche, Argentina.

1.4 Waterlogging. All trees affected and several nearby ones have already died. Celtis africana , Pretoria, South Africa.

1.5 Bacterial leaf scorch caused by Xylella fastidiosa, is a systemic disease. Quercus velutina, Raleigh, North Carolina, USA.

Altered growth or development
Colour changes in crown

Not all changes in colour indicate disease or insect attack [1.10]. Always compare the suspected problem with the condition or appearance of trees at different times of year. Nutrient imbalances in the soil are often blamed for colour changes and other altered growth responses, but little information exists about this for non-commercial tree species.

1.6 Drought damage.
Trees weakened by poor Pinus patula, Venezuela.

1.7 Probably drought damage. Pinus sp., Chuquisaca, Bolivia.

1.8 Boron deficiency, a recognized condition planting. on Pinus patula. Colombia.

1.9 Yellows disease (and dieback) due to phytoplasma disease. Melia azedarach, Santa Cruz de la Sierra, Bolivia.

1.10 Normal loss of foliage and colour change as the dry season begins. Toona ciliata, Zomba, Malawi.
1.11 [left] Note the discolouration throughout the tree, the result of fungal canker damage caused by Cryphonectria cubensison the main stem (not visible in this photo). Eucalyptus sp., Brazil.

Altered growth or development
Galls, swelllings and knots

The examples in Plates 1A and 1B illustrate a wide variety of causes. Nutrient disorders and “site factors” are often said to be the cause of poor health, as determined by the appearance of crowns. But also look out for symptoms such as smaller leaves [1.2] and unusual patterns of leaf discolouration [1.5].

2.1 Mite-induced galls causing significant damage in nurseries. Vangueria infausta, Gaborone, Botswana.

2.2 Galls of the rust fungus, Atelocauda digitata. Acacia mangium, Kalimantan, Indonesia.

2.3 Rust fungus, Diorchidiella verlandii infests stems and also causes dieback in crown. Mimosa schomburgkii, Vicosa, Brazil.

2.4 Swellng at edge of canker is part of the healing process. Pinus sp., Brazi.

2.5 Rust infection causes enlargement of pine cone. Cronartium strobilinum on Pinus elliottii, USA.

2.6 Note swelling below the flowering region, possible due to the pink fungus fruiting on the surface. Calliandra calothyrsus, Trujillo, Honduras.

2.7 Crown gall caused by Agrobacterium tumefasciens. Inga edulis, Río Chico, Bolivia.

2.8 Olive knot caused by the bacterium Pseudomonas savastanoi. Olea europaea, Spain.

Altered growth or development
Distortion of leaves and stems

A variety of pests can distort leaves and sometimes young, still fleshy stems. The effects can be transient [3.2], as in some incidences of insect feeding, but other altered growth forms can be accompanied by serious losses [3.3].

3.1 Virus disease produces distorted (shoestring) leaves on youngest stems. Gliricidia sepium, Vado Hondo, Guatemala.

3.2 Leaf curling and death of stems of unknown origin. Possibly due to insect feeding or virus disease. Uapaca kirkiana, Zomba, Malawi.

3.3 Stubby shoot disease reduces flowering and fruit production. Cause unknown. Sclerocarya birrea, Gaborone, Botswana.

3.4 Psyllid attack (Calophya rubra) produces pits on stems and leaves and weakens them. Schinus molle, Cochabamba, Bolivia.

3.5 Symptoms of aphid damage considered by some farmers to be related to those shown left for peach leaf curl and called by the same name. Prunus persica, Sucre, Bolivia.

3.6 [left] Peach leaf curl, a highly distinctive fungus disease caused by Taphrina deformans.
Prunus persica, Epizana, Bolivia.

Altered growth or development
Growth stimulation

Infection or pest attack can cause extra or additional growth which is often weaker than normal and may lead to dieback.

4.1 [right] Extensive sprouting of leaves along stems in declining trees associated with ash yellows, a phtoplasma disease. Fraxinus udhei, Bogotá, Colombia.

[far right] Foxtailing is linked with predisposing genetic traits plus environmental influences. Pinus sp., Cochabamba, Bolivia.

4.3 Increased leaf production on very young stems soon falls off. Gliricidia little leaf disease, caused by a phytoplasma. Gliricidia sepium, Honduras.

4.4 Animal grazing has stimulated new growth on right. Unknown street tree, Cochabamba, Bolivia.

4.5 Witches' broom caused by the rust fungus Endoraecium acaciae. Acacia koaia, Hawaii.

4.6 Additional shoots formed with apparently smaller leaves. This type of symptom is difficult to interpret on unfamiliar trees. Suspected phytoplasma disease. Azanza garckeana, Gaborone, Botswana.

4.7 Spectacular growth at top of this tree is due to phytoplasma infection. Aphanamixis polystachya (Meliaceae), Dinajpur, Bangladesh.

Altered growth or development
Stunted or reduced growth

Reduced growth may indicate poor growing conditions [5.1]. Major losses can occur when pests are not involved [5.4].

5.1 Compare reduced growth on left with seedling on right. Poor nutrition or lack of water are possible causes. No obvious indication of virus disease. Erythrina falcata, Cochabamba, Bolivia.

5.2 This native species grows up to 4,000 masl and beyond, but here it is performing poorly at 2,500 masl. Cause of “problem” is not known but could simply be poor nutrition. Polylepis incana, Cochabamba, Bolivia.

5.3 Gliricidia little leaf disease (phytoplasma). Internode length is greatly reduced giving this densely foliated stem. Gliricidia sepium, Zamorano, Honduras.

5.4 Greatly reduced internodes, barren lower stems and bunches of small leaves at the apex are known as “giraffes' necks”, a symptom of neem decline. Thought to be associated with drought. Azadirachta indica, near Sokoto, Nigeria.

5.5 Melia yellows disease. Stimulation of growth from main trunk. Leaves are much smaller and internode length is reduced, hence the compact bunches. These leaves soon die and fall away. Melia azedarach, Cochabamba, Bolivia.

5.6. Healthy foliage shown on the left and that caused by phytoplasma disease shown on the right. Melia azedarach, Bolivia

Altered growth or development
Premature loss of leaves or stems

Early drop of leaves is linked to pest [6.2] and non-pest [6.1] causes although in the former case trees would usually exhibit other symptoms such as root decay. The effect of abiotic influences such as drought is often temporary with trees becoming healthy as more rain falls. Pathogens and diseases have more fundamental and longer-term impacts on tree health.

6.1 Sparse crowns and early leaf drop as well as giraffe neck symptoms indicate neem decline. Thought to be associated with drought. Azadirachta indica, Damaturu, Nigeria.

6.2 Loss of leaves is due to phytophthora root disease. Alnus glutinosa, Sussex, UK.

6.3 Premature death of culm sheaths is the first sign that culm tissues below are dying. Guadua angustifolia, Quindío, Colombia.

6.4 Loss of leaves is due to a bacterial wilt disease caused by Pseudomonas syzygii, known as Sumatra disease. Syzygium aromaticum, North Sumatra, Indonesia.

6.5 Loss of foliage (and yellowing) due to bacterial wilt caused by Ralstonia solanacearum. Casuarina equisetifolia, China.

General death

Blight is a general term used to describe death of foliage or stems, often in the absence of any distinctive symptom.

7.1 Bamboo blight, suspected fungal disease. Note brown, dead portions of blighted culms. Bambusa vulgaris, Chittagong, Bangladesh.

7.2 Dying bamboo in foreground which looks like blight, is due to flowering of bamboo. Arundinaria alpina, Ethiopia.

7.3 Web blight caused by the fungus Koleroga noxia. Such blights are common on many plants and are caused by various fungi. Theobroma cacao, Tingo Maria, Peru.

7.4 Loss of leaves above confirms advanced root disease, probably due to the fungus Ganodermasp. Acacia mangium, Riau, Indonesia.

7.5 Neem scale insect, Aonidiella orientalis. Azadirachta indica, eastern Nigeria on the Cameroon border.

7.7 Attack by the fungus Botryosphaeria dothidea. Pinus taeda, Hawaii, USA.

7.6 Leaf blight (scorch) caused by herbicide drift in nursery. Acacia mangium, Kalimantan, Indonesia.

7.8 Patch of brown and dried-up leaves indicates mammal feeding on stem, probably by squirrels. Betula pendula, Sussex, UK.

General death

Note that not all stems without leaves in the crown are necessarily dead. Dieback is associated with many different causes, from root and trunk diseases to the broader effects of poor growing conditions and waterlogging.

8.1 Note minor dieback at left due to little leaf disease (phytoplasma). The yellow foliage is also abnormal. Gliricidia sepium. Jutiapa, Guatemala.

8.2 Same tree as 8.1 photographed exactly one year later. Note more extensive dieback.

8.3 Dieback due to unknown cause in street tree. Catalpa bignonioides, Baden-Baden, Germany.

8.4 Apparent dieback. Birds have stripped the foliage to make nests but stems may still be alive. Azadirachta indica, Garoua, Cameroon.

8.5 Dieback is common in hedgerow trees whose roots may be affected by agricultural practices. No primary involvement of pests. Fraxinus excelsior, UK.

8.6 Dieback possibly due to mechanical interference with root system. Sterculia quinqueloba, Mangochi town, Malawi.

8.7 Dieback due to possible ganoderma root disease. Nothofagus sp., Rotorua, New Zealand.

General death
Wilt and collapse

Wilting of foliage is often less distinctive in woody hosts when compared to the wilting of fleshy leaves of annual crops. Wilts are the result of internal blockages and are often accompanied by internal staining of stems [9.5]. Note that obtaining clear photos of wilt symptoms in crowns is often difficult; affected branches should be removed and photographed separately.

9.1 Wilt symptoms thought to be associated with fusarium root disease. Dalbergia sissoo, near Borga, Bangladesh.

9.2 Close-up of the wilt and "blighted" leaves shown in 9.1.

9.3 Feeding by the tea mosquito, Helopeltis antonii, induces wilt-like symptoms. Azadirachta indica, India.

9.4 Lethal yellowing disease of palms. Cocos nucifera, Florida, USA.

9.5 Internal staining and bacterial ooze (appears brown). See 9.6 for wilt symptoms. Eucalyptus sp., Mexico.

9.6 Bacterial wilt, caused by Ralstonia solanacearum. Eucalyptussp., Mexico.

9.7 Takamaka wilt caused by the fungus Leptographium calophylii.Calophyllum inophyum, Praslin, Seychelles.

Localized death
Spots and lesions

Spots and lesions are common and it is not always easy to distinguish between insect feeding, fungi, bacteria, viruses and the effects of nutrient disorders. With stem lesions, carefully remove tissues to look for necrosis below [10.6].

10.1. Lesions possibly due to the fungus Kiamyces sp. Eucalyptus sp., Thailand 22

10.2 Common leaf spots associated with the fungus Septoria sp. Polylepis incana, Bolivia.

10.3 Fungal leaf spots caused by Cercospora meliae. Melia azedarach, Dinajpur, Bangladesh.

10.4 Dothistroma blight. Banding and colour changes occur on needles rather than distinct spots. Pinus radiata, Ecuador.

10.5 Some fungal infections affect large areas rather than cause distinct spots. Cylindrocladium sp. on Eucalyptus urophylla, Brazil.

10.6 Young bacterial cankers (Pseudomonas savastanoi) that lack thecorky appearance of older lesions. Fraxinusexcelsior, Yorkshire, UK.

10.7 Fungal leaf scabs caused by Apiosphaeria guaranitica. Tabebuia serratifolia, Vicosa, Brazil.

10.8 Insect galls and yellowing. Ficus sycomorus, Mangochi, Malawi.

10.9 Suspected virus-caused discolouration and flecking on foliage. Gliricidia sepium, Honduras.

Localized death

Cankers can vary considerably in appearance: some have raised edges and cavities while others look more like galls or knots. The underlying tissues should be examined to see if there is necrosis and evidence of disease.

11.1. Serious and fatal fungal canker caused by Coniothyrium zuluense. Eucalyptus sp. Kwazulu, South Africa. Also shown below in 11.5.

11.2 Contrast these fungal cankers caused by Nectria galligena with the bacterial cankers shown in 11.3. Fraxinus excelsior, Surrey, UK.

11.3 Bacterial cankers caused by Pseudomonas savastanoi sometimes referred to as "knots". Fraxinus excelsior, Yorkshire, UK.

11.4 Fungal canker due to Cryphonectriacubensis. Eucalyptus sp., Brazil.

11.5 Fungal cankers, Coniothyrium zuluense. Eucalyptus sp., KwaZulu, South Africa.

11.6 Canker or knot of unknown origin. Uapaca kirkiana, Perekezi, Malawi.

Localized death

Some cankers do not have large cavities [11.7]. Note the features of gummosis on eucalypts [11.12 and 11.13].

11.7 Bleeding from Seiridium cardinale fungal cankers. Cupressus lusitanica, Pretoria, South Africa.

11.8 Cankers associated with several different fungi. Acacia sp., Kalimantan, Indonesia.

11.9 Hypoxylon mammatum, fungal canker. Populus sp., USA.

11.10 Blister bark disease caused by a fungus. Casuarina equisetifolia, Karnataka, India.

11.12 Gummosis, a symptom associated with abiotic factors. Eucalyptus sp., place unknown.

11.11 Canker due to Pheinus noxius. Hevea brasiliensis, Kalimantan, Indonesia.
11.13 Dark areas above exposed to show exudation of liquid known as kino.

Localized death
Rots and decays

Rots and decays are classified according to the place where they occur, e.g. heartrot [12.2] or according to colour [12.3]

12.1 Suspected pythium root infection. Eucalyptus sp., KwaZulu, South Africa.

12.2 Suspected Ganodermasp. infection. Acer pseudoplatanus, France.

12.4 Root and butt brown (cubicle) rot associated with Laetiporus sulphureus. Casuarina equisetifolia, Senegal.

12.3 Bluestain caused by various fungi. Pinus caribaea var. hondurensis, Venezuela.

12.5 Root rot, probably Ganoderma sp. Acacia mangium, Riau, Indonesia.

12.6 Healthy tissue on left, decay on right, associated with decline. Austrocedrus chilensis, Bariloche, Argentina.

12.7 Secondary fungal growth on culm surface. Suspected bacterial disease has caused decay. Guadua angustifolia, Quindío, Colombia.

12.8 Fungal mats of Armillaria mellea, a widespread cause of root rot and tree death in temperate and subtropical areas. Metrosideros polymorpha, Hawaii.

Physical evidence
Damage by insect and animal feeding

Observing insects feeding on foliage is not always possible although some types of damage are unmistakable [3.7].

13.1 Psyllid infestation (Heteropsylla cubana). Leucaena leucocephala, Nepal.

13.2 Tunnels made by unknown beetle larvae. Pterocarpus indicus, Mahé, Seychelles.

13.3 Beehole borer, Xyleutes ceramicus in young tree. Gmelina arborea, Kalimantan, Indonesia.

13.4 Empty larval case and frass is evidence of internal feeding by the beehole borer shown in 13.3. Photographs from same tree.

13.5 Bark feeding by Phoracantha sp. Sprouting below dead region of trunk. Paraserianthes falcataria, Kalimantan, Indonesia.

13.6 Leaf miner (Neolithocolletis pentadesma) damage. Pterocarpus indicus, Mahé, Seychelles.

13.7 Leaf skeletonizer (insect feeding damage). Uapaca kirkiana, Mzuzu, Malawi.

Physical evidence
Damage by insect and animal feeding

Wilting of foliage in [13.11] and [13.13] is due not to systemic infection by pathogens but to animals feeding on the bark. Trees usually recover the following year.

13.8 Aphid feeding. Black material is fungal growth, “sooty mould”. Prunus persica, Pocona, Bolivia.

13.9 Grazing by unidentified insect. Unknown host, Mahé, Seychelles.

13.10 Leaf tier. Name of insect not known. Dillenia sp., Kalimantan, Indonesia.

13.11 Feeding damage (squirrels) similar to that shown in 13.13. Acacia mangium, Kalimantan, Indonesia.

13.12 Feeding damage by deer. Gmelina arborea, Indonesia.

13.13 Bark stripping by squirrels leads to wilt and chlorosis. Acer pseudoplatanus, Surrey, UK.

Physical evidence
Pest infestation

Infestations are easy to observe and often cause concern, but their significance may be less than assumed.

14.2 Aphids feeding. Unknown shrub, Cochabamba, Bolivia.

14.1 Rust fungus Uleiella paradoxa kills seeds and forms black masses. Araucaria araucana, Dead China, Chile.

14.3 Scale insect. Citrus, Trinidad, Bolivia.

14.4 White mycelial sheath of Erythricium salmonicolor. Eucalyptus sp., Brazil.

14.5 Velvet mould due to growth of the fungus Septobasidum sp. Citrus, Santa Cruz, Bolivia.

14.6 Powdery mildew as shown by white bloom on leaves. Buddleja sp., Cochabamba, Bolivia.

14.7 Dark mycelial mat of Phellinus noxius. Delonix regia, Saipan Island, Marianas.

14.8 Termites surface feeding on bark, not damaging. Brachystegia sp., Malawi.

14.9 Termites nest (empty). Paraserianthes falcataria, Kalimantan, Indonesia.

Physical evidence
Pest infestation

Observing insects feeding on foliage is not always possible although some types of damage are unmistakable [3.7].

14.10 Rust fungus (Melampsoraallii-populina). Populus sp., Cochabamba, Bolivia.

14.11 Rust fungus (Chaconia ingae) with raised pustules. Inga cylindrica, Santa Cruz, Bolivia.

14.12 Gall mite (Aceria litchii) on lychee seen as "fur" on underside of leaves. Litchi chinensis, Thai Nguyen, Viet Nam.

14.13 Parasitic plant in crown as shown by the red flowers of Ligaria cuneifolia. Schinus molle, Santa Cruz, Bolivia.

14.15 Pink disease caused by Corticium salmonicolor affects many species. Acacia sp., Sumatra, Indonesia.

14.14 Root feeding termites (Coptotermes sp.) can cause severe damage. Gmelina arborea, Kalimantan, Indonesia.

14.16 Aggregation of larvae known locally as sika sika (? Tolype sp.). Schinus molle, Cochabamba, Bolivia.

Physical evidence
General Damage

Unusual growth events [15.2] or damage [15.3] are best resolved by first looking for evidence of necrosis and then making enquiries about possible sources of mechanical damage.

15.1 Hail damage. The scars have healed over the original damage. Prunus persica, Nor Cinti, Bolivia.

15.2 Drought-induced. The ooze is from extra-floral nectaries. Note shortening of internode length. Azadirachta indica, Nigeria.

15.3 Damage by grass cutting equipment. Acacia xanthophloea, Pretoria, South Africa.

15.5 Tapping for resin. Pinus merkusii, Central Java, Indonesia.

15.4 Damage caused by pruning for shade above tea plantation. Grevillea robusta, Tamil Nadu, India.

15.6 Illegal tapping for sap, which is used to make an alcoholic beverage. Acacia sp., Karnataka, India.
15.7 [left] Frost damage. Pinus radiata, Rotorua, New Zealand.

15.8 Deliberate ring-barking of trees is killing them. Paraserianthes falcataria,Mahé Seychelles.

Physical evidence
General Damage

Bad pruning is a common source of future problems as the cut surfaces allow the entry of potential pathogens. Poor planting stock weakens future growth and makes trees more susceptible to insect attack.

15.9 Poor nursery practice leads to twisted roots. Trees grow poorly. Acacia mangium, Kalimantan, Indonesia.

15.10 Ragged pruning allows fungi to enter and establish heart rot. Acacia mangium, Kalimantan, Indonesia.

5.11 Normal sap bleeding. Guides cut trees for tourists and this results in scars. Pterocarpus indicus, Mahé, Seychelles.

15.12 Pruning to remove overhanging branches. Fraxinus udhei, Bogotá, Colombia.

15.13 Pruning to avoid interference with electrical cables, but clumsily performed. Fraxinus udhei, Pereira, Colombia.

15.14 Flux from junction of main trunks. Cause unknown. Trees “bleed” for physiological and pathological reasons. Acacia auriculiformis, Kalimantan, Indonesia.

Physical evidence
Other grows on trees

Although plants and lichens do not cause direct harm to trees, they may have some effect or importance. Lichen patterns on stems may superficially resemble possible pathogenic fungi [16.6]

16.2 Epiphytic plants (bromeliads) weigh down branches. Theobroma cacao, near Quevedo, Ecuador.

16.1 One of several common bromeliads found on cocoa. Theobroma cacao, Equador.

16.3 Lichens festoon the crowns of several trees in the miombo woodlands. Mzuzu, Malawi.

16.4 Lichen growths. Araucaria araucana, Dead China, Chile.

16.5 Lichens growing on culms. Guadua angustifolia, Quindío, Colombia.

16.6 Colourful patterns on trunk due to several species of lichens. Paraserianthes falcataria, Indonesia.

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