Quarantine pests

The Colorado beetle belong to the leaf beetle family, Chrysomelidae. The Colorado beetle reproduces itself quickly and is gluttonous, which makes it a difficult and feared plant pest. The damage to the potato leaf caused by the beetle considerably reduces the harvest.

The adult Colorado beetle is easy to recognise. The body of the beetle is oval or round with characteristic black and white stripes running the length of the body. It has black spots on its head and pronotum. It is about 1 cm long, somewhat larger than a ladybird.

The Colorado beetle’s eggs are yellow to bright orange and around 2 mm long. They are laid in clusters on the underside of the leaf and are difficult to distinguish from ladybird eggs.

Newly hatched Colorado beetle larvae are just under two millimetres long and tomato red in colour. Older larvae are lighter red to orange and can be up to 12 mm long. The larvae are oval or round and have two rows of black dots running down each side of the body.

• Pictures of Colorado beetles (gd.eppo.int)

Symptoms

Adult individuals and larvae both eat potato leaves and, in the case of severe infestation, the Colorado beetles can eat so much that the potato blast becomes completely bare. The beetle also leaves black sticky faeces on the potato leaf.

Distribution

The Colorado beetle is present in North America, parts of Asia and in most European countries.

How they spread

Full-grown beetles and larvae spread with potato plants, tubers and in packages with potatoes. Colorado beetles are also spread in packages with fresh vegetables that come from areas where the beetle is present. Adult individuals can be spread far by wind and even on water.

Risk of misidentification

There are one insect that can be misidentified as a Colorado beetle. The pupas and larvae of the Colorado beetle can be confused with the pupas and larvae of a ladybird.

If you have a Colorado beetle infestation

The Colorado beetle can cause great damage to a potato field. Previous assessments showed that the Colorado beetle could most probably become established in Blekinge, Gotland, Halland, Kalmar and Skåne counties if it were to be introduced. In these counties, the Colorado beetle is a quarantine pest, which requires official measures to be taken if it is found.

If you suspect that you have found a Colorado beetle, its egg or larvae, you must notify the county administrative board or the Swedish Board of Agriculture. Collect and kill the beetles, for example, by putting them in boiling water or the freezer.

• Form: Notify quarantine pests

Epitrix is a genus of small beetles which are flea beetles. The beetles are 1.5–2 mm long and jump away like a flea when disturbed. Four species of Epitrix infest potato plants and can cause great damage to potatoes. Leaves, roots and tubers are infested by beetles and their larvae, and the harvest can be impossible to sell because of the damage.

Symptoms

Adult beetles chew on leaves, creating shot-like round holes. The holes are approximately 1–1.5 mm in diameter. Larvae chew on the surface of the potato tubers. The passages can extend for up to 1.5 cm in the tubers. The tunnels created by larvae can lead to the tuber splitting and the surrounding tissue becomes cork-like.

Distribution

The flea beetles as a group include approximately 180 species, most of which are found in North and Central America. Within the EU, there are a couple of species of Epitrix in Spain and Portugal but we have not yet found any of these species in Sweden.

If Epitrix comes to Sweden, it is likely that they would survive here. Then they would also be a great risk for our potato cultivation.

How they spread

Epitrix spreads through trading with potatoes or through accompanying soil, for example, plants and root crops that come from an area where Epitrix occurs. Trading with potatoes to Sweden from areas in Spain and Portugal where Epitrix is present is insignificant. However, there is a risk that you as a private individual may bring Epitrix home with you if you have potatoes with you from a trip abroad.

If you have an infestation of Epitrix

If you suspect that you have an infestation of Epitrix, you must notify us.

• Form: Notify quarantine pests

The root knot nematodes Meloidogyne chitwoodi and Meloidogyne fallax are closely related species that live in soil and plant material. The nematodes’ life cycle consists of three stages: egg, larva and the adult stage.

Meloidogyne chitwoodi and Meloidogyne fallax have many different species of plant as hosts. The potato is the root knot nematodes’ preferred host, but it can also live on carrot, sugar beet and all types of grass, including cereals. Nematodes are not dangerous for human beings but are a threat to potato crops if they spread.

• Pictures of Meloidogyne chitwoodi and Meloidogyne fallax (gd.eppo.int)

Symptoms

Common symptoms are weak plants with poor growth. This can lead to infection by other diseases and crop yield and losses. Tuber-like swellings can be seen on tubers and roots, so called galls. Potato tubers have dead brown patches in areas underneath the skin.

Distribution

IIn the EU, the nematodes have been found in Belgium, Denmark, France, Germany, Lithuania, the Netherlands, Portugal, Spain and Sweden. In Sweden, nematodes have been found in four areas: Blekinge, Skåne, Halland and Västra Götaland. They also exist outside Europe but import of seed potatoes and soil from countries outside the EU is prohibited.

How it spreads

Nematodes have little ability to move. They are most effectively spread by potato seed and soil from infected fields. Sharing agricultural machinery is believed to further spread nematodes between fields once they have been introduced into a field.

Prevent spread

Be aware of the risks and spread of the nematodes. Risk mitigation measures include appropriate crop rotations and using only certified seed potatoes as a common cultivation practise. Make sure to clean machines prior to moving them between fields, especially when sharing equipment between many places of production.

If you have an infestation of root knot nematodes

Plots found to be infested by the root knot nematodes will be subject to measures with the aim to eradicate the infestation. Measures entail black fallow for at least a year, followed by cropping restrictions and prohibitions on movement of soil, until nematodes have been eradicated.

If you suspect that you have an infestation of root knot nematodes, you must notify us.

• Form: Notify quarantine pests

Potato cyst nematodes are microscopic eelworms that live in and damage the roots of potatoes. The potato is the potato cyst nematode’s most important host plant, although it may also infest tomatoes and wild plants of the potato family (for example, black nightshade and bittersweet).

Potato cyst nematodes can cause great losses in potato cultivations in the case of major infestations. It is therefore important to take measures to eradicate and prevent spread of the potato cyst nematode before they have time to propagate too much.

There are two species of potato cyst nematodes:

• the yellow potato cyst nematode, Globodera rostochiensis
• the white potato cyst nematode, Globodera pallida.

• Pictures of Globodera rostochiensis (gd.eppo.int)
• Pictures of Globodera pallida (gd.eppo.int)

Symptoms

The symptoms are rather diffuse and include patches with reduced growth and sometimes yellowing or withered potato blast. When infested, the size of the tubers may be reduced.

Distribution

Both yellow and white potato cyst nematodes have been present in Sweden for a long time, although the white potato cyst nematode is not especially common.

How they spread

Nematodes are spread as cysts with seed, plants for planting, soil, bulbs, and potatoes for consumption or industrial processing.

If you have an infestation of potato cyst nematodes

If you notice or suspect an infestation of white potato cyst nematodes, you must notify it to the Swedish Board of Agriculture or the County Administrative board.

You must also contact the Swedish Board of Agriculture if you suspect or note that a specific potato variety that has been resistant to potato cyst nematodes is no longer resistant.

You do not need to notify if you suspect that it is yellow potato cyst nematode. Yellow potato cyst nematode is today such a common plant pest in potato cultivation that there is an exemption from the obligation to notify to the Swedish Board of Agriculture.

• Form: Notify quarantine pests

Brown rot is caused by the bacterium Ralstonia solanacearum.

• Pictures of brown rot (gd.eppo.int)

Symptoms

The symptoms can be most clearly seen by cutting through a potato tuber. Yellowish-brown discolouring will then be visible in and yellowish-white bacteria drops will ooze out from the vascular ring without needing to squeeze the tuber.

The disease can also exist in a latent form for several generations of potatoes.

Distribution

Many European countries have detected the bacterium Ralstonia solanacearum.

How it spreads

Brown rot spreads in a number of ways. The most common pathway for spreading is by seed potatoes, but it can also be spread through machinery, equipment, weeds and irrigation water. Bacteria can survive freely in the soil but it is unclear how long they would survive during Swedish conditions.

If you an infestation of brown rot

If you suspect that you have an infestation of brown rot, you must notify us.

• Form: Notify quarantine pests

Potato ring rot is caused by the bacterium Clavibacter sepedonicus.

• Pictures of potato ring rot (gd.eppo.int)

Symptoms

The symptoms can be most clearly seen by cutting through a potato tuber. An infected potato with mild symptoms shows scattered or contiguous yellow spots at the vascular ring. If you squeeze a cut tuber, the yellow-coloured tissue will be pressed out as a creamy ooze. In more severe infestation, the vascular ring may be more liquid and brown-coloured. There are seldom symptoms one the aboveground parts of potato plants.

The disease can also exist in a latent form for several generations of potatoes.

Distribution

Potato ring rot is present in many European countries but also in some countries in Asia and in North America.

How it spreads

Bacteria are most commonly spread via infested seed potatoes. Other means of spreading the bacterium is through shared machinery used in potato cultivation and equipment for sorting and packaging potatoes.

If you use machines such as potato harvesters which also are used by other potato growers, you must clean and preferably disinfect these machines when moving from farm to farm. It should be noted that cold temperatures does not kill the infection.

If you have an infestation of potato ring rot

If you suspect that you have an infestation of potato ring rot, you must notify us.

• Form: Notify quarantine pests

If you would like to read more

• Brochure: Light ring rot on potatoes – in Swedish

Potato wart disease is a soil-borne disease caused by the fungus Synchytrium endobioticum. The fungus lives as a parasite inside the cells of the potato plant and causes uncontrolled growth. Infestation of potato wart disease leads to a deterioration of the quality of the tubers and the number of tubers decreases.

Dormant spores of the fungus can survive for more than 20 years in soil. Potato wart disease may cause extensive financial losses for growers.

• Pictures of potato wart disease (gd.eppo.int)

Symptoms

Young tubers that are infested may become spongy and deformed. The fungus infects the eyes of older tubers which subsequently develop warty growths resembling the shape of cauliflowers. Initially the warts are white or green but they darken over time. Warts can also appear on stems and stem bases.

Distribution

There are around 40 different pathotypes of potato wart disease in the world and most of them are spread in the EU.

There are four pathotypes in Sweden: pathotype 1, 8, 18 and 40. Strain 8, 18 and 40 have to date only been found in eastern Skåne and western Blekinge, while pathotype 1 is found at a number of places from Skåne up to the counties of Västerbotten and Norrbotten.

How it spreads

Potato wart disease spreads with seeds or soil from fields which are infected with potato wart disease.

If you have an infestation of potato wart disease

If you suspect that you have an infestation of potato wart disease, you must notify us.

• Form: Notify quarantine pests

The bronze birch borer is a buprestid beetle that infests birch.

Symptoms

The larvae chew tunnels through conducting tissue that transports nutrition in the tree. If the damage is sufficiently severe, the transport of nutrition decreases or ceases and the tree dies. Species of birch that are common in Europe, for example, Betula pendula and Betula pubescens, are very sensitive to infestation.

Distribution

The bronze birch borer originates in North America. They have not been found outside North America.

How they spread

Long-distance spread takes place most probably through transport of infested plants and wood products that are manufactured from infested wood. Wood products are, for example, wood packaging material and dunnage used in transport. The greatest risk is untreated wood products such as tree chips that are used to produce energy, in particular if the chips are stored outdoors close to a stand of birch trees.

Risk of misidentification

The bronze birch borer is similar to the emerald ash borer, Agrilus planipennis, both in appearance and in behaviour except that Agrilus planipennis infests other species of trees. In Sweden, there is Agrilus betuleti which is found on birch trees and which also resembles the bronze birch borer.

If you suspect an infestation by the bronze birch borer

If you suspect an infestation by the bronze birch borer, you must notify us.

• Form: Notify quarantine pests

The citrus long-horned beetle and the Asian long-horned beetle are large beetles that live in deciduous trees. The trees are damaged and eventually die as the larvae chew large tunnels in the wood. They both infest deciduous trees of various species.

The different species resemble one another in appearance but differ somewhat in lifestyle.

• The citrus long-horned beetle infests the lower part of the stem, the stem base and roots of host trees with a trunk diameter exceeding 1 cm.
• The Asian-long horned beetle infests high up on the stem and in the crown of host trees with a trunk diameter exceeding 5 cm.
  

• Pictures of citrus long-horned beetle (Anoplophora chinensis) (gd.eppo.int)
• Pictures of the Asian long-horned beetle (Anoplophora glabripennis) (gd.eppo.int)

Symptoms

Large exit holes (10–15 mm i diameter) in trees that have been purchased in the past three years, or frass resembling sawdust on the ground, is an indication that there are pests in the tree. Other indications that should raise suspicion is larval tunnels larger than three mm in wood packaging material originating from areas where the pests are known to be present.

Distribution

While originating from China, the beetles are also found in Indonesia, Japan, Korea, Malaysia, Myanmar, the Philippines, Taiwan, and Vietnam.

The citrus long-horned beetle is established in Lombardy in northern Italy where it can no longer be eradicated.

The Asian long-horned beetle has spread on repeated occasions in Europe, often from larvae that have arrived here in wood packaging material in connection with import from Asia, in particular China. The longhorn beetle causes significant costs due to the destruction of trees and the extensive efforts required for eradication. In our vicinity, the citrus longhorn beetle was combated in an industrial area in Finland between 2015 and 2020, when the outbreak was declared eradicated. The Finnish plant protection authority Ruokavirasto confirmed that the beetle had reproduced at the site, and the outbreak primarily affected birch trees.

We have not found any citrus long-horned beetles or Asian long-horned beetles on trees in Sweden. If the long-horned beetles were to be introduced into Sweden, they could survive and reproduce in Götaland and the coastal regions up to the lake Mälaren area.

How they spread

Long-distance spread of eggs, larvae, or pupae occurs through trade with infested plants for planting and infested wood materials such as wood packaging material and dunnage.

Risk of misidentification

The small white-marmorated longhorn beetle (Monochamus sutor) which is common in Sweden is often mistaken for the citrus long-horned beetle or Asian long-horned beetle.

• SLU Swedish Species Information Center’s (Artdatabanken) pictures of Monochamus sutor (artfakta.se) – in Swedish

If you suspect an infestation of citrus long-horned or Asian beetle

If you suspect an infestation of citrus long-horned beetle or Asian long-horned beetle, you must notify us. You must contact us if you find living larvae or insects in wood packaging material from countries outside the EU.

• Form: Notify quarantine pests

The red-necked longhorn beetle is a long-horned beetle that inhabits forests, urban areas, and orchards. It attacks, lives in, and causes damage to trees of the Prunus genus, such as bird cherry, cherry, damson, wild cherry, and plum. The beetles can be found in both living plants and in timber, wood products, and wood packaging materials.

In the event of an outbreak in Sweden, the most important measure is to fell and destroy all infested trees. If this pest were to be introduced into the country, it would have serious consequences, both through damage to trees and economic losses.

The flight period of the red-necked longhorn beetle extends from March to August, with peak activity from May to mid-July. The adult female lays eggs in cracks in the bark near the base of the trunk, no more than 30 cm above the ground, but also in larger branches.

• Pictures of the red-necked longhorn beetle (gd.eppo.int)

Symptoms

The greatest chance of detecting infested trees is during the most active period of the larvae. At that time, reddish frass resembling sawdust from larvae can be found after emergence. The frass is located on the ground near the tree, mixed with larval excrement.

It is the larvae that cause damage to the trees by gnawing on and underneath the bark, as well as into the wood. They create tunnels in branches and the trunk, disrupting the nutrient supply of the host tree. The most obvious symptom is round exit holes, usually found on the trunk up to about 30 cm above the ground.

Distribution

The beetle’s historical distribution includes China, North and South Korea, Mongolia, and Vietnam. More recently, the red-necked longhorn beetle has been found in Japan and in three locations within the EU: Italy (in the regions of Campania and Lombardy) and Germany (Bavaria).

How it spreads

The spread can occur through trade in plants, wood, wood products, and wood packaging material from infested areas.

Special rules for import to the EU and movement within the EU

As the pest has probably been spread through plants, wood, wooden products or wood packaging material of the Prunus family, there are rules on imports to the EU and movement within the EU from countries where the beetle is present.

If you intend to import plants for planting or move such plants within the EU, there are special rules for plants whose trunk or root crown diameter is at least 1 cm at the thickest point. These plants are large enough for the long-horned beetle to go through a complete life cycle.

Risk of misidentification

The goat moth (Cossus cossus) which lives on deciduous trees, including the species that the red-necked longhorn beetle infests, can also give rise to a collection of feces on the ground by the tree. However, there is no risk of misidentification if one sees individual goat moths as they do not at all resemble the red-necked longhorn beetle.

If you suspect an infestation by the red-necked longhorn beetle

If you suspect an infestation by the red-necked longhorn beetle, you must notify us.

• Form: Notify quarantine pests

The Siberian conifer silk moth and the white-lined silk moth are two closely related lappet moths which infest different species of coniferous trees.

• Pictures of Dendrolimus sibiricus (gd.eppo.int)

Symptoms

Larvae can cause noticeable defoliation of infested pine trees, larches and spruce trees. Fully grown larvae of the Siberian conifer silk moth (50–80 mm) and the white-lined silk moth (60–82 mm) are large and visible.

Distribution

Both pests originate from Asia, and the Siberian conifer silk moth has spread to central Russia.

If they were to establish in Sweden, it could have serious consequences, as Swedish conifer species and the Swedish climate are favourable for both species of lappet moths.

How they spread

Natural spread can occur over long distances, as adult lappet moths can fly up to 100 km per year. All life stages can be transported on host plants or cut branches, such as those from spruce. Transport of roundwood with bark left, wood packaging material, and dunnage from areas with infested trees could also carry the lappet moths.

Risk of misidentification

The pine lappet moth (Dendrolimus pini) which is common in Sweden is very similar to the Siberian conifer silk moth.

• ASLU – Swedish Species Information Centre’s information and pictures of pine-tree lappets (artfakta.se) – in Swedish

If you suspect an infestation of the Siberian conifer silk moth or white-lined silk moth

The Siberian silk moth (Dendrolimus sibiricus) is a quarantine pest.

We also encourage you to notify us of suspected incidences of the white-lined silk moth (Dendrolimus superans). While not a quarantine pest yet there is no legal obligation to notify us. However, it is a pest of concern that has not been found in Sweden before.

• Form: Notify quarantine pests

The fungus Fusarium circinatum can infect all parts of pine trees and cause severe damage. It can also affect Douglas fir.

Another older name for Fusarium circinatum is Gibberella circinata.

Symptoms

In nurseries, the fungus can cause significant damage in seedbeds, resulting in poor seedling emergence. On branches and stems of larger plants, it causes cankers with heavy resin flow. Inside the cankers, brown rot is visible, often encircling the branch. The branch dies above the point of infection.

Distribution

In Europe, the fungus is present in forests in northern Spain. It has also been found in France and Portugal.

How it spreads

Over long distances, plants and seeds are the main pathways for spread. Locally, the fungus spreads via wind and insects.

The risk of spread to Swedish forest nurseries is low, as seeds from areas where the fungus occurs are not used. Additionally, the fungus does not thrive in our cold climate.

If you suspect an infestation by Fusarium circinatum

If you suspect an outbreak of pitch canker of pine (Fusarium circinatum), you must notify us.

• Form: Notify quarantine pests

The Japanese beetle infests over 300 different species of trees, bushes and agricultural crops. Adult individuals infest leaves, fruit and flowers while larvae infest roots and sometimes grass.

• List of host plants (gd.eppo.int)

The beetle has a charismatic appearance that is easy to recognise. It is oval in shape and metallic green with a bronze shell. There are five white tufts of hair on each side of its shell and a couple of white tufts at its rear end. The Japanese beetle is 8–11 millimetres long and 5–7 millimetres wide.

Symptoms

Adult individuals like to infest the sunlit parts of host plants where they chew holes on leaves and the petals of flowers. The Japanese beetle is gregarious and aggregates when there are a number of individuals. Clusters of beetles can be seen on infested leaves, flowers or fruit. The infestation usually begins at the top of the plant and the beetles then work their way downwards. In the event of severe infestation with a large number of beetles, they can chew the leaves so much that only the midrib remains. Infested leaves turn brown and may fall off. Whole plants can be consumed when there is a large beetle population.

The larvae cause damage by chewing on the roots of the host plants, giving rise to various symptoms depending on the variety of plant.

Symptoms appear on infested grass such as thinner growth or withered sections or brown patches where the grass has died.

• Pictures of Japanese beetles and symptoms (gd.eppo.int)

Distribution

The beetle is widespread in Japan, Canada, and the United States. It has also been found in eastern Russia, Italy, Portugal, Switzerland, and Slovenia.

How it spreads

It spreads through international trade, in particular with plants for planting, plant products, in packaging or hitching a ride on, for example, boats and aircraft. Larvae can be transported in soil around plants for planting, for example, grass rolls.

When Japanese beetles have been introduced and become established in an area, they can spread by themselves. Adult individuals can fly up to 8 kilometres but most of them do not fly more than 50 metres at a time. In ongoing outbreaks in Italy, the beetle has a spread rate of about 10 kilometres a year.

Risk of misidentification

I Sweden, there is the garden chafer Phyllopertha horticola which resembles the Japanese beetle to some extent. However, the garden chafer lacks the white tufts of hair along its shell and at its rear which the Japanese beetle has.

• Pictures of the garden foliage beetle (gd.eppo.int)

If you suspect an infestation of Japanese beetles

If you suspect an infestation by Japanese beetles, you must notify the Swedish Board of Agriculture.

• Form: Notify quarantine pests

Chestnut blight is a serious fungal disease on sweet chestnut (Castanea sativa). The fungus damages sweet chestnut severely or kills it. Once the disease is introduced it is difficult to eradicate.

Chestnut blight does not affect the common horse chestnut (Aesculus hippocastanum).

• Pictures of chestnut blight (gd.eppo.int)

Symptoms

Infected branches develop light brown sunken lesions, and cracked wounds may appear on the trunks of infected trees. The fungus can grow so rapidly that branches become girdled before a callus (healing tissue) has time to form around the wounds. The trunk or branches above the cankers die, and the leaves remain wilted and hanging on the dead branches.

Fruiting bodies known as pycnidia form and produce spores in bark lesions. In humid weather, spores may ooze out, appearing as orange-yellowish threads. Spores are the life stage of the fungus that spreads and infect healthy trees. Under the bark in the wounds, a pale brown fungal mycelium may also develop, often in a fan-shaped pattern.

Distribution

Chestnut blight exists in most European countries, Australia and some countries in Asia, the Middle East and North America.

How it spreads

The chestnut blight is spread over long distances through trading with plants and timber made of sweet chestnut. The fungus spreads over shorter distances by wind, water and insects.

If you suspect an infestation by chestnut blight

If you suspect an infestation by chestnut blight, you must notify the Swedish Board of Agriculture.

• Form: Notify quarantine pests

Phytophthora ramorum is an oomycete (water mold) that causes the disease ramorum blight. This plant disease has been shown to affect a wide range of plant species, and new host species are continually being discovered. The disease is very difficult to control, and if the oomycete were to establish itself in Sweden, it could cause significant economic and ecological damage.

• Pictures of Phytophtora ramorum (gd.eppo.int)

Symptoms

Symptoms vary widely and may include wilted leaves, shoots, and branches, as well as sunken lesions on the lower part of the trunk that exude a reddish-brown fluid.

Distribution

The disease is widespread in many parts of Europe and the United States. In Sweden, Phytophthora ramorum has only been confirmed in a few isolated cases on rhododendrons imported from other EU countries.

How it spreads

Long-distance spread occurs through trade in ornamental plants such as Rhododendron and Viburnum from countries where the pathogen is present. Trade in bark, timber, and soil from infected areas can also spread Phytophthora ramorum.

If you suspect an infestation by Phytophthora ramorum

If you suspect an outbreak of ramorum blight (Phytophthora ramorum), you must notify the Swedish Board of Agriculture.

Isolates of Phytophthora ramorum that are established within the EU are classified as regulated non-quarantine pests. Other isolates are considered EU quarantine pests. In the event of a confirmed case, the Swedish Board of Agriculture will determine the type of isolate. Regardless of your assessment of the isolate’s origin, you are required to report any suspected outbreak.

• Form: Notify quarantine pests

The plum curculio is a weevil that attacks plants in the rose family, such as roses, apples, plums, cherries, and pears. The weevil has also been found on plants in the currant and blueberry family.

Adult individuals are about 7 millimeters long, with a snout and reddish-brown elytra marked with black, bumpy spots. When disturbed, the weevil plays dead and drops to the ground.

Symptoms

Adults feed on flowers, leaves, and young fruit. When attacking young fruit, the weevil creates characteristic egg-laying scars shaped like a crescent or a swallow. Infestations lead to premature fruit drop, except in cherries, where the fruit continues to develop and ripen on the tree. Small exit holes caused by the weevil larvae may be observed on fruit that have dropped to the ground.

• Pictures of the plum curculio and typical egg laying wounds and scars (gd.eppo.int)

Distribution

The plum curculio is found in Canada and the United States.

How it spreads

The pest spreads through international trade, most likely as pupae in soil or as adults in packaging materials. Spread through infested fruit, with the exception of cherries, is less likely, as attacks usually cause premature fruit drop.

Risk of misidentification

There are over 400 weevil species in Sweden, so misidentification with similar species is likely.

If you suspect an infestation by plum curculio

If you suspect an infestation by the plum curculio, you must notify the Swedish Board of Agriculture.

• Form: Notify quarantine pests

Emaravirus rosae infests all plants belonging to the rose family. Emaravirus rosae was previously called rose rosette virus (RRV).

• Pictures of rose rosette virus (gd.eppo.int)

Symptoms

Symptoms on roses can vary. The most common symptom is abnormally increased growth. Symptoms may appear in the following ways:

• Thickened stems, making the plants resemble succulents
• increased leaf production
• deformed leaves
• leaves displaying patterns in various shades of green (known as mosaic)
• shoots with intense red pigmentation
• deformed flower buds and flowers

Infected plants have reduced winter hardiness, and the disease causes a gradual decline in plant health. Infected plants typically die within 1 to 5 years post infection.

Distribution

The virus is present in India, Canada and the USA. The virus is widespread in the USA where an increased occurrence has been seen in roses.

How it spreads

The virus is spread in the following ways:

• a gall mite, Phyllocoptes fructiphilus
• mechanically through, for example, pruning or grafting
• trade with infected plant material.

If you suspect an infestation by Emaravirus rosae

If you suspect an infestation by Emaravirus rosae you must notify us.

• Form: Notify quarantine pests

The emerald ash borer is a beetle that infests ash trees. As the ash is a common tree species in Sweden, an establishment of Agrilus planipennis could have major ecological and financial consequences.

• Pictures of the emerald ash borer (gd.eppo.int)

Symptoms

The larvae eat the cambium layer under the bark of ash trees. The damage caused by chewing leads to foliage being thinned out or turning yellow and branches that wilt and die. Infestation by the emerald ash borer leads to the tree dying after a few years. The exit holes created by adult beetles in infested trees are characteristically D-shaped. There are no other jewel beetles in Europe that infest ash trees and cause damage similar to that caused by the emerald ash borer.

Distribution

The beetle originated in East Asia but has spread to Canada, the USA and Russia and most recently to Ukraine. In Canada and the USA, Agrilus planipennis has caused great destruction of ash trees, which are a common component of urban environments as street trees. The emerald ash borer has not been found in Sweden.

How it spreads

Long-distance spreading takes place through trade with plants and wood products such as timber, wood packaging material, dunnage, wood chips and wood. In the USA, most observations of the emerald ash borer have been in connection with import of dunnage. The emerald ash borer can moreover fly up to 1 km and in this way spread locally.

If you suspect an infestation by the emerald ash borer

If you suspect an infestation by the emerald ash borer, you must notify us.

• Form: Notify quarantine pests

If you would like to read more

• Factsheet: Agrilus planipennis (gd.eppo.int)

The pine wood nematode is a millimetre long nematode (a kind of round worm) that causes pine wilt disease. The pest is capable of causing severe wilting and death of coniferous forest stands. The nematode lives inside trees where it causes damage to the vascular system which in turn prevents trees from taking up water.

• Pictures of the pine wood nematode (gd.eppo.int)

Symptoms

Needles of infested conifers first turn yellow before wilting and falling off. Infected pines can ultimately die.

Distribution

The pine wood nematode is naturally spread with the aid of various species of long-horn beetles belonging to the genus Monochamus. There are several species of Monochamus present in Sweden that can spread pine wood nematode.

How it spreads

The pine wood nematode is primarily spread through trade with infested wood or wood packaging material.

The pine wood nematode was discovered for the first time in Europe in 1999 and is now established in Portugal, on the mainland and the island of Madeira. The pine wood nematode has also spread to Spain. An infected tree was found in Extremadura in 2008. Since then, three new infestations have been found in Spain. These are small outbreaks of the pine wood nematode and Spain has succeeded in eliminating three of these cases by pest management. It is therefore untreated wood from Portugal which is the greatest risk.

If you suspect an infestation by the pine wood nematode

If you suspect an infestation by the pine wood nematode, you must notify us.

• Form: Notify quarantine pests

The round-headed apple-tree borer (Saperda candida) is a beetle belonging to the longhorn beetle family. In Sweden, other species of the genus Saperda are known as wood borers. The round-headed apple-tree borer primarily attacks apple trees, but other trees and shrubs in the rose family can also serve as host plants.

If this beetle were to be introduced and spread in Sweden, it could have serious economic consequences, especially for apple orchards, but also for nurseries, as a range of fruit trees and shrubs could be affected.

• Picture of Saperda candida (bugguide.net)

Symptoms

The larvae cause the most damage by boring tunnels, primarily in the lower part of the trunk of both healthy and weakened trees. Their feeding can girdle the trunk, eventually leading to the death of the tree.

Distribution

Saperda candida is native to North America and is not currently found in Sweden. The pest has only been detected once outside its natural range, in northern Germany.

How it spreads

Long-distance spread most likely occurs through the trade of plants for planting. There is also a risk that wood could carry the pest.

If you suspect an infestation by the round-headed apple-tree borer

If you suspect an infestation by the round-headed apple-tree borer, you must notify us.

• Form: Notify quarantine pests

Xylella fastidiosa is an aggressive bacterium that causes extensive damage to plants. The bacterium has many different host plants and more have been detected as we have gained more experience. It causes great damage to various crops such as cherries, plums, olives, grapes and citrus fruit as well as oak, elm and ornamental plants. The bacterium has also been found, for example, in rosemary and myrtle.

Symptoms

The symptoms are very varied and infected plants can be symptom-free. The symptoms may include yellowing and dying leaves or wilting of leaves or plant parts. If a fruit tree is infested, the size of the fruits may be reduced.

Distribution

The bacterium originates in the USA and Latin America. At present, damage from the bacterium has been noted in certain areas in Italy, France, Spain and Portugal. Xylella fastidiosa has probably arrived in southern Italy with coffee bushes imported as ornamental plants from Costa Rica.

How it spreads

The bacterium is spread to new places by trading of plants for planting that may carry either the bacterium or insects that spread the Xylella fastidiosa. One of the insects that spread the bacterium is the meadow spittlebug, Philaenus spumarius.

The import of ornamental plants is the most probable scenario for how both Xylella fastidiosa and insects that carry the bacterium could spread to Sweden.

If you suspect an infestation by Xylella fastidiosa

If you suspect an infestation by Xylella fastidiosa, you must notify us.

• Form: Notify quarantine pests

If you would like to read more

• Om Xylella fastidiosa (eppo.int)
• The European Commission’s host plant list for Xylella fastidiosa (ec.europa.eu)

The apple maggot is a fruit fly which mainly infest apples but also species of the hawthorn family.

Adult flies are 4–5 millimetres long with a wing span of 7.5–9 millimetres. The body is mainly black with a white marking on the back and three lighter stripes over its rear end. The wings are transparent with black wing markings which characteristically form the letter F.

Symptoms

Adult individuals lay eggs in fruit. Infested fruits appear lumpy or scarred as a result of repeated egg-laying wounds. Some discolouring is visible around the wounds. The larvae in the fruit damage the pulp and cause brown-coloured streaks.

• Pictures of the apple maggot and symptoms (gd.eppo.int)

Distribution

The apple maggot is present in Canada, Mexico and the USA.

How it spreads

It spreads through international trade and transport of infested fruit or soil that contains pupas. Once the fly has been introduced, it can fly further and establish itself in new areas. The apple maggot is able to fly as far as 4.5 kilometres.

Risk of misidentification

The cherry fruit fly (Rhagoletis cerasi) which is common in Sweden, may be mistaken for the apple maggot. However, the cherry fruit fly has a yellow instead of a white marking on its back and its wing bands do not form the letter F as in the apple maggot.

• Pictures of the cherry fruit fly (gd.eppo.int)

If you suspect an infestation by the apple maggot

If you suspect an infestation by the apple maggot, you must notify the Swedish Board of Agriculture.

• Form: Notify quarantine pests

The silverleaf whitefly is a tiny insect, about one millimetre in length.

The silverleaf whitefly can infest more than 300 plant species, including common greenhouse vegetables, many potted plants, and bedding plants. In addition to poinsettia, begonia, fuchsia, gerbera, hibiscus, and verbena are also known hosts. Bemisia tabaci has been shown to transmit up to 60 different viruses, with the Geminivirus genus causing the most significant economic losses.

Sweden is a protected zone for Bemisia tabaci (European populations), which means the country must remain free from the pest or actively work to eradicate it. Plants or plant products imported into Sweden from other EU countries or from outside the EU must not contain the silverleaf whitefly.

• Pictures of the silver leaf whitefly (gd.eppo.int)

Symptoms

The symptoms caused by the silverleaf whitefly can be confused with those caused by the greenhouse whitefly (Trialeurodes vaporariorum), which is relatively common in Europe.

Nymphs and adult whiteflies are found on the undersides of leaves, where they feed on plant sap. This leads to yellow (chlorotic) spots. Excretions from the feeding whiteflies, known as honeydew, contaminate the plant and provide a breeding ground for sooty molds, which hinder plant growth. Additional symptoms caused by virus transmission may include leaf curling, yellowing, mosaic patterns in various shades of green, or yellowing of leaf veins.

Distribution

The silverleaf whitefly is widespread in Europe and on all other continents. It is not established in Sweden, as infestations have so far been successfully eradicated through control and sanitation measures.

How it spreads

Long-distance spread occurs through trade in infested plants for planting and cut flowers. Trade in poinsettias appears to be a major factor in the spread of the silverleaf whitefly within Europe and the Mediterranean region. Although adult whiteflies are poor fliers, they can be carried over longer distances by wind.

If you suspect an infestation by the silverlead whitefly

The silverleaf whitefly is a quarantine pest in Sweden and must be reported. If you detect an infestation, you are required to notify the Swedish Board of Agriculture.

• Form: Notify quarantine pests

Thrips palmi is a thrips species and a serious pest that attacks a wide range of plant species. Plants in the cucumber, legume, and nightshade families are particularly vulnerable. Among ornamental plants, chrysanthemum, cyclamen, and orchids are frequently affected. Ornamental plants such as weeping fig (Ficus benjamina) can also be infested.

Thrips palmi has developed resistance to certain common pesticides, making it difficult to control. In Japan, biological control using predatory mites has shown success. In Australia, insecticidal soap is recommended for vegetable cultivation.

• Pictures of Thrips palmi (gd.eppo.int)

Symptoms

Melon thrips hides in crevices on host plants. It feeds by sucking sap from plant cells, leaving behind empty cells that give the tissue a silvery appearance. Leaves, shoot tips, and flowers develop silvery streaks and spots that later dry out and turn brown, especially along the leaf veins. During severe infestations, leaves may appear silver or bronze-coloured. Additionally, leaves, fruits, and shoot tips may become deformed and stunted.

Distribution

Thrips palmi originates from Southeast Asia and has spread across much of Asia. It has also been found in some African countries, Australia, Iraq, South America, the Caribbean, Hawaii, and Florida. In European greenhouses, occasional outbreaks have occurred, but no permanent establishment has been reported.

How it spreads

Long-distance spread occurs through trade of infested plants for planting, fruits, or packaging materials. Thrips palmi has been intercepted multiple times in shipments to European and Mediterranean countries during import inspections of host plants. The species has limited ability to spread long distances on its own.

Risk of misidentification

The melon thrips is just over one millimeter long and resembles the onion thrips (Thrips tabaci), which is common in Swedish greenhouses during cultivation of cucumbers. Expert identification is required for accurate diagnosis.

Thrips palmi can also be confused with the honeysuckle thrips (Thrips flavus), a relatively common thrips species. Microscopic examination is necessary to distinguish Thrips palmi from Thrips flavus.

• Pictures of carnation-thrips Thrips tabaci (cabi.org)

Thrips palmi can also be confused with Thrips flavus, a relatively common thrips. Microscopic investigation is required to be able to distinguish Thrips palmi from Thrips flavus.

• Pictures of Thrips flavus (gbif.org)

If you suspect an infestation by melon thrips

If you suspect an outbreak of the melon thrips, you must notify the Swedish Board of Agriculture.

• Form: Notify quarantine pests