Connecticut State The Connecticut Agricultural Experiment Station

Sycamore and London Plane Tree (Platanus)

Plant Health Problems
Diseases caused by Fungi:
Anthracnose, Apiognomonia veneta.
This is a very common disease throughout Connecticut, especially during cool, wet springs. Symptoms appear as large, brown patches that develop along veins or at leaf margins as the leaves expand in spring. This often results in extensive tattering and distortion and severely infected leaves drop prematurely. The fungus can also cause a blighting and dieback of tender shoots which can result in deformity. Near to complete refoliation usually occurs and trees seem to survive these yearly infections. The same fungus causes a similar condition on white oaks and overwinters on fallen leaves and small branch cankers on both hosts. While common this disease is usually not fatal.
Fertilize trees in the spring, and water during drought to reduce stress. Rake and dispose of fallen leaves to reduce the chance of infection in the following season. Since this disease is usually not a serious problem for the health of the trees, chemical controls are usually not necessary.
Powdery mildew, Microsphaera.
Heavy coating of whitish gray, powdery growth usually on the upper surfaces of the leaves. Some distortion of leaves and young shoots may occur if infection is early in the season. London plane trees are particularly susceptible.
Rake and remove fallen leaves, provide good air circulation around the tree, and avoid late day watering. Fertilize trees in the spring and water during dry weather to maintain tree vigor. Since this disease is usually not a serious problem for the health of the trees, chemical controls are usually not necessary.
Canker stain, Ceratocystis fimbriata f. sp. platani.
Lethal cankers on London plane trees and sycamore seen first as a black or brown coloration, generally in a lens-shaped pattern, on the smooth yellow or green bark. Cankers elongate rapidly, and expand sideways slowly to girdle the branch or trunk. A dark reddish-brown or bluish-black discoloration of the wood extends all the way to the pith of the tree.
Pruning infected material well back of any discoloration in the wood may prevent further spread. Fertilize trees in the spring and water during dry weather to maintain tree vigor. Avoid insect and mechanical injuries to reduce chances of infection.
Insect Problems:
American plum borer, Euzephera semifuneralis.
The larva of this moth is a secondary pest, injuring stressed trees by feeding on the inner bark and cambium. The winter is passed as a white cocoon located under loose bark. Cream colored moths with a 1″ wingspan appear in May. They mate, and the female lays eggs singly or in groups in bark crevices. Eggs hatch in a matter of days and the young larvae, after finding an opening, enter the bark. They begin feeding, making frequent holes to push out the red frass. The larvae mature in 4 – 6 weeks and are about 1″ long with a brown head capsule. Among the products registered for control of this pest in Connecticut is permethrin, which can be applied to the stems and trunks of affected trees in mid to late May to manage adults. The insect pathogenic nematode, Steinernema carpocapsae, can be applied to stems and trunks to control larvae in burrows. Consult the label for dosage rates and safety precautions.

Aphids.
A large gray aphid, Longistigma caryae, is found on the bark and twigs of sycamore. Insecticidal soap or malathion, which are among the compounds registered for use against this pest in Connecticut, will control this insect as a contact spray. Imidacloprid applied to the soil as a systemic also works well. Consult the labels for dosage rates and safety precautions.

Sycamore lace bug, Corythucha ciliata.
This lacebug is very common on the undersides of sycamore leaves. On the upper surface, small white marks show where this bug has sucked the sap from the underside of the leaf. The adult bugs overwinter under the edges of the bark and other places where they can find protection. Soon after the leaves unfold, the bugs emerge and lay eggs on the undersides of the leaves. The eggs hatch, and the nymphs pass through five stages and become adults in a little more than a month. Two or more generations occur per year. Malathion, ultrafine horticultural oil or insecticidal soap, which are among the compounds registered for use against this pest in Connecticut, sprayed twice, ten days apart, in the spring will control this pest on shade trees. Imidacloprid applied as a systemic for root uptake will provide at least one season of control. Consult the labels for dosage rates and safety precautions.

Sycamore leaf folder, Ancylis platanana.
The caterpillar of this little moth folds the leaf and feeds in the fold, chiefly along the midrib near the base of the leaf. The adult has a wingspread of about 1/2″ and is dull orange in color with darker, wavy bands. Spraying shade trees with acephate, malathion, or spinosad, which are among the compounds registered for use against this pest in Connecticut, will control it. Consult the label for dosage rates and safety precautions.

Sycamore plant bug, Plagiognathus albatus.
This pest overwinters as an egg near the leaf bud. Egg hatch follows the emergence of leaves in the spring. Adults and nymphs are yellowish-green with dark eyes. They feed on leaves causing chlorotic spotting. These areas turn brown and fall out of the leaves, gives them a ragged appearance. The nymphs can be controlled by spraying with ultrafine horticultural oil, insecticidal soap or malathion which are among the compounds registered for control of this pest in Connecticut. Imidacloprid applied as a systemic to be taken up by the roots will also provide season-long control. Consult the label for dosage rates and safety precautions.

Terrapin scale, Mesolecanium nigrofasciatum.
This small, reddish, oval, convex scale occurs on the small twigs of sycamore, often killing them. It varies from 1/16 – 1/8″ long and is usually reddish-brown mottled with black. Eggs are deposited in June under the old shells and there is one generation each year. Among the compounds registered for control of this pest in Connecticut are horticultural oil, malathion and imidacloprid. Horticultural oil may be applied in early spring to control overwintering eggs, or use a spray of malathion in April to kill crawlers. To determine when crawlers are active, wrap black tape around infested limbs and coat the tape with Vaseline. The light-colored crawlers are easily seen on the tape. Imidacloprid may also be applied as a systemic to be taken up by the roots. Consult the labels for dosage rates and safety precautions.

Whitemarked tussock moth, Orgyia leucostigma.
The caterpillars of this insect feed on sycamore. This insect has two generations each year, and spends the winter in frothy white egg masses on the trees. Eggs hatch in late May and the caterpillars mature about July 1. They make their gray cocoons on the trees. Two weeks later, the moths emerge and females usually lay egg masses on the old cocoons. The second generation larvae hatch in July and mature in August. The caterpillars reach a length of about 1 1/2″. They are striped lengthwise with brown and yellow, and are hairy, with four upright white tufts on the front half, two long black hairs near the head, and a similar one on the tail. There is a bright red spot just behind the head. The female is ash-gray without wings. The male has prominent feathered antennae and ash-gray wings with darker gray markings. It has a wingspread of about 1 1/4″. This caterpillar can be controlled by sprays of malathion, carbaryl, spinosad or Bacillus thuringiensis var. kurstaki, which are among the compounds registered for use against this pest in Connecticut. Consult the label for dosage rates and safety precautions.

Anthracnose of Plane Tree

Article provided courtesy of International Society of Arboriculture. Cover photo image citation: Joseph O’Brien, USDA Forest Service, Bugwood.org.

The term “anthracnose ” is used for a disease that affects a variety of shade trees. The species of fungus that results in anthracnose in plane trees is Apiognomonia veneta. Of the various types of plane trees, the American sycamore (Platanus occidentalis) is the most susceptible to the disease, with the oriental plane (P. orientalis) being much more resistant. The London plane, existing as a number of different clones (e.g., P. x hispanica), varies in susceptibility.

Signs of anthracnose in these trees include:

• Shoot blight: Young leaves and shoots may die back in spring, making the tree look as though it has suffered from frost damage.

• Bud blight: Buds may fail to open at all, sometimes on entire twigs or branches.

• Leaf blight: Leaves develop patches of dead tissue, most characteristically surrounding some of the main leaf veins.

• Twig blight: Affected leaves frequently fall prematurely, often while they are still predominantly green. Severely affected trees can shed the majority of their leaves by early summer. Twigs may be killed, and cankers may develop on larger branches.

Even severely affected trees usually recover to produce new growth by mid-summer. However, the overall vigor of the tree can be reduced, and branch growth may become distorted if frequent dieback occurs.

The fungus actively colonizes buds and twigs when the plant is dormant and susceptible during mild weather in autumn, winter and early spring. Twig dieback occurs when a canker enlarges and girdles the twig. Trees with significant bud and twig mortality produce thin crowns through late spring. In early spring, spores are produced on dead one-year-old twigs that infect expanding shoots and leaves. Infected shoots suddenly wilt and appear scorched, commonly following spring rains. Leaf blight of newly developed leaves also occurs, especially on the lower branches. Infected leaves develop tan to reddish-brown lesions that typically appear in the center of the leaf and extend along the leaf’s veins.

Image Citation: William Jacobi, Colorado State University, Bugwood.org

To help control anthracnose non-chemically, sweep up and burn fallen leaves, if practical. On young, small trees, it may be possible to prune out affected twigs or branches. Wet leaf surfaces promote establishment of this disease — improve air circulation and sunlight penetration by thinning crowded stands and pruning to thin the canopy. Maintain health of trees by providing adequate water and fertilizer. Healthy trees are more likely to recover from anthracnose infection than stressed trees.

Chemical sprays to control anthracnose are rarely justified, except when the disease occurs in stressed or recently transplanted trees, or when the disease causes repeated defoliations. Fungicide applications to prevent infections in the spring are sometimes warranted. If fungicide is required, use a labeled material containing thiophanate-methyl, chlorothalonil or mancozeb in spring. Fungicide injections are also used in spring and fall to systemically control the disease.

Post Topics: Arborists, Environment, ISA (International Society of Arboriculture)

Massaria disease

A fungus may be the cause of branch drop on plane trees

Plane trees (Platanus x hispanica) in Britain are reported to be suffering from Massaria disease, which causes large lesions on the upper surfaces of major branches and can cause branch drop. The cause is thought to be the fungus Splanchnonema platani (formerly called Massaria platani).

This resource page will help you to identify Massaria disease and the fungus that may cause it.

Details of the disease

In 2009 tree management teams in London began to notice large lesions and branch drop on the branches of plane trees. Similar symptoms had recently been seen on lesions of plane trees in mainland Europe, most notably in Germany, Austria, the Netherlands and parts of France.

Spores of the fungus Splanchnonema platani, formerly called Massaria platani, were found to be associated with the lesions. However it is not yet clear whether this is the primary cause of Massaria disease.

Identify the fungus

Forest Research has sequenced the DNA of spores isolated from tree lesions and confirmed S. platani to be present. We have also found:

  • Characteristic brown, multi-septate pycnidiospores
  • Occasionally characteristic ascospores
  • The fungus seems to sporulate freely in Europe and spores are quite easy to identify under a microscope
  • Until recently it was difficult to find sporulation on British samples

Find out how to identify S. platani spores

Our research

Forest Research is collecting fresh samples of lesions from planes trees to establish the cause of Massaria disease, and to see if lesions result from S. platani or subsequent infections with opportunistic basidiomycetes such as Auricularia spp.

Researchers are comparing cultures of S. platani with others from across Europe to establish if:

  • Isolates from tree lesions in Britain are native and becoming more pathogenic because of climate change or changes in management
  • S. platani was introduced from Europe on un-sterilised tools, infecting planting stock, or on the wind
  • How it might behave in a warmer climate
  • What other pathogens might affect plane trees

Further information

More information on this subject is available in:

Tubby, K. V. and Rose, D. R. (2009). Problems facing plane trees. Arboriculture Association Newsletter. 144, Spring. 18–19.

Plane trees in London

Problems on plane trees

Disease problems in the Genus Platanus

Mr John S. Brereton

In Melbourne as in other parts of the world various forms of Platanus are widely grown suiting the parks, boulevards and avenues to be found in urban areas where large ornamental trees (25-30m height, 20-25m width) are preferred. The Plane often tolerates polluted air and compacted soil conditions making an ideal hardy choice for roadsides and streetscapes. The Plane generally exhibits a degree of drought tolerance under Australian conditions but is sometimes a problematic tree selection due to outbreaks of Microsphaera alni, Powdery Mildew and Apiognomonia veneta (asexual:Discula platani) Plane Anthracnose. The latter disease problem is more serious and apart from the obvious aesthetic problems post infection the disease also places the trees under stress. Stressed trees are likely to be more susceptible to other infectious and non-infectious problems including insect attack.

Planes are generally known world wide as being susceptible to Plane Anthracnose a fungal disease caused by Apiognomonia veneta. This disease problem is also refered to in the United States as sycamore anthracnose. The Sycamore (Platanus racemosa) specifically the endemic American form, is generally considered to be the most susceptible to anthracnose. The London plane (Platanus x acerfolia) is less susceptible and Oriental Plane (Platanus orientalis) exhibits a high degree of resistance by comparison. Cultivars of Platanus x acerfolia ‘Liberty’ & ‘Columbia’ are found to be faster growing and more resistant to anthracnose than the parent.

Anthracnose symptoms expressed include the following:

Spring twig blight destroys previous years growth at the tips;
Destruction of buds;
Blight of new growth and young leaves;
Cankers may form in older more mature trees growing at the base of twigs and girdling new shoots;

Major leaf blight causing leaf distortion and marked brown necrotic areas on leaves crossing over the veins. These areas enlarge and will often cover most of the leaf surface. Leaf drop may follow in severe cases. This disease in leaves should not be confused with scorching from heat and drought stress. The distinctive elongated brown lesions on leaves crossing over veins should avoid any confusion with drought stress.

In young trees under nursery growing conditions it may also be more difficult to maintain strong apical dominance as terminal buds are destroyed.

Planes receiving adequate water and nutrients usually re-foliate in summer.

Climatic conditions favouring outbreaks of anthracnose. Outbreaks of anthracnose are more likely when during periods of wet weather in spring and early summer, with the disease surviving and over-wintering

The fungal organism over winters in cankers in twigs and branches

During the Spring spores which lie within infected tissue are produced and released to be spread by wind and rain or water splash.

Management of anthracnose.

  • The maintenance of tree vigour is important with adequate nutrient and water supply.
  • Removal of infected twigs and branches by pruning is beneficial. This will be usually confined to peripheral growth resulting in limited control of the disease problem
  • Under nursery conditions do not use overhead irrigation methods that will result in long periods of leaf wetness and high humidity levels
  • Maintain adequate air circulation between trees.
  • Raking up infected leaves twigs which have fallen may have little impact on disease control as parts of the tree are already infected and a source of infective spores.
  • Applications of fungicides such as copper formulations, triadimefon, chlorothalonil and mancozeb have assisted to contain but not eradicate this disease problem. Fungal applications are usually applied at approximately 10 to 14 day intervals from bud swell. The application must be strictly in accordance with all label instructions. The application method must ensure adequate coverage particularly under nursery conditions.

Plane tree

Plane tree, any of the 10 species of the genus Platanus, the only genus of the family Platanaceae. These large trees are native in North America, eastern Europe, and Asia and are characterized by scaling bark; large, deciduous, usually palmately lobed leaves; and globose heads of flower and seed. The plane trees bear flowers of both sexes on the same tree but in different clusters. The sycamore maple (Acer pseudoplatanus), often called sycamore, plane, or mock plane, is distinct (see maple).

Leaves and seedballs of the Oriental plane tree (Platanus orientalis)A to Z Botanical Collection/Encyclopædia Britannica, Inc.

The American plane tree, or sycamore (P. occidentalis), also known as buttonwood, buttonball, or whitewood, is the tallest, sometimes reaching a height of more than 50 m (160 feet). Its pendent, smooth, ball-shaped seed clusters usually dangle singly and often persist after leaf fall. Native from southeastern Europe to India, the Oriental plane (P. orientalis) reaches 30 m (100 feet) with huge, often squat boles—some measuring nearly 10 m in circumference (about 10 feet in diameter). Its bristly seedballs hang in clusters of two to six. The London plane (P. acerifolia), a hybrid between the American and the Oriental planes, combines characteristics of both in varying degrees. It is a little shorter and more squat than the American tree and usually has bristly, paired seedballs. There are variegated forms of London plane. The California sycamore (P. racemosa), about 25 m (80 feet) tall, has contorted branches, thick leaves, and bristly seedballs in groups of two to seven.

The London plane is planted widely in cities for its resistance to air pollution and to diseases that more readily affect other plane trees. All planes grow rapidly and furnish quick shade. Many are picturesque in winter for their patchy bark: as the outer bark flakes off, inner bark shows up in shades of white, gray, green, and yellow.

London planetree

Tree & Plant Care

Plants grow best in moist, deep, rich well-drained soil in full sun. Does not tolerate shady sites.
Soil pH adaptable, moderately salt and drought tolerant.
Can be a messy tree since drops a lot of leaves, twigs and fruit.

Disease, pests, and problems

Can be affected by canker stain, anthracnose, leafspots, aphids, plant bug, scales, and borers.
Young plants can be susceptible to frost cracks.

Disease, pest, and problem resistance

Some cultivars vary in their resistance to anthracnose (see cultivars below).
Tolerant of high pH soil.

Native geographic location and habitat

Of hybrid origin.

Bark color and texture

Unique, gray-brown flaky scales that shed to expose mottled peeling patches of white, gray, and green. Trees become nearly white near the top of tree.

Leaf or needle arrangement, size, shape, and texture

Simple, alternate, 6 to 7 inch wide leathery leaves have 3 to 5 lobes, similar to maple.
The leaf surface is bright green and paler underneath; margins are untoothed or nearly so.
Fall color is yellow-brown.

Flower arrangement, shape, and size

Monoecious, with separate male and female flowers. Flowers appear in early spring with the leaves as dense globose balls on long stalks (peduncles).
Male flowers are green , females are showier, bright burgundy-red.
Not ornamentally important

Fruit, cone, nut, and seed descriptions

Ball-like seed heads (1 inch diameter) hang in pairs from long stalks. Seeds shatter during winter months.

Cultivars and their differences

‘Bloodgood’ (Platanus x acerifolia ‘Bloodgood’): Shows some resistance to anthracnose.

Exclamation!™ (Platanus x acerifolia ‘Morton Circle’): This cultivar is resistant to anthracnose and frost cracking. The habit is more uniform and upright than the species. Grows 60 feet high and 30 feet wide. Introduced by Chicagoland Grows®, Inc.

Ovation™ (Platanus x acerifolia ‘Morton Euclid’): This cultivar is also resistant to anthracnose and frost cracking. The habit is rounded to broadly pyramidal. Grows 60 feet high by 50 feet wide. Introduced by Chicagoland Grows®, Inc.

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