Pine wood nematode

Frequently Asked Questions about the Pine Wood Nematode

1. What is the pine wood nematode and how will I recognise it?

The pine wood nematode (Bursaphelenchus xylophilus) is a microscopic worm measuring about one millimetre and invisible to the naked eye. Finding and identifying it always requires a laboratory examination.

2. What are the symptoms and signs of the pine wood nematode in living trees and packaging materials?

In trees, the pine wood nematode lives in the wood and reproduces rapidly. Over time, it blocks the tree's sap flow, resulting in yellowing and eventual death. These symptoms are similar to those of trees dying of drought, but whose needles do not fall. In wood, the pine wood nematode feeds on, for example, the epithelial cells of the tree's resin canals. When the tree dies, the pine wood nematode begins to feed on the hypha of blue stain fungi. For this reason, blue stain fungi in packing materials made of coniferous wood provides suitable food for the pine wood nematode.

3. Where is the pine wood nematode from and where does it live? How does it spread?

The species is originally from North America. From there it spread to Asia before reaching Portugal, presumably through Asia. In North America, the pine wood nematode occurs in the United States, Canada and Mexico. In Asia, the pine wood nematode occurs in Japan, China, Taiwan and Korea. In Europe, it has so far only spread to Portugal. In 2009, the EU declared the whole of Portugal as infested with pine wood nematode.

4. How did the pine wood nematode spread from North America to the rest of the world?

Due to increasing global trade, it spreads in contaminated coniferous wood or packaging materials made of such wood.

5. What are the host species of the pine wood nematode?

It lives only in coniferous trees. The most important host species is the pine, but it can also live in other conifers such as spruce or larch.

6. The pine wood nematode is transported by wood boring beetles of the genus Monochamus. How?

Fully grown wood boring beetles lay their eggs in debilitated standing trees, or in round, unbarked trees felled or broken by the wind. The eggs develop into larvae which live and pupate inside the wood. If the pine wood nematode lives in the same tree, the species infest the fully grown beetle emerging from the pupa. Fully grown wood boring beetles leave their tree of birth and transfer the pine wood nematodes to new trees, where they feed on pine shoots or lay their eggs.

7. How does the pine wood nematode spread from packaging materials to forests?

The risk of the species spreading is highest when both pine wood nematodes and wood boring beetles infest the same packaging material. Upon completing their pupation, the beetles leave the packaging and fly into nearby forests. As packaging materials are often left outside warehouses, where they lie unused, there is then a real risk of the pine wood nematode spreading.

8. Can the pine wood nematode be eradicated?

No chemical pesticides or biological repellents are available for protecting forests from the pine wood nematode. The most important measure is preventing its spread into the forest. For this reason, the EU has imposed restrictions on the import of conifers and coniferous wood products. For example, importing living conifers from non-EU countries is entirely forbidden. Furthermore, a phytosanitary certificate is mainly required and diverse handling requirements must be met when importing coniferous wood products from non-EU countries. The requirement for a phytosanitary certificate enables the inspection of all imported batches. Wooden packaging materials are controlled under their own regulations, which comply with the ISPM 15 standard.

9. How to dispose of packaging materials contaminated by the pine wood nematode?

The best and most commonly used method is to burn them. This has to be done under safe and supervised conditions. The permission of the fire authorities is often needed. If required, they can also offer help with burning.

10. Can official inspections ensure that all contaminated wooden packaging materials are destroyed?

No. The authorities are only able to control a fraction of all batches imported from countries where pine wood nematode occurs. Evira appeals to importers to increase their number of inspections, targeting them specifically at packaging arriving from risk countries.

11. What is the point of findings if it is impossible to catch every contaminated batch?

Each finding matters. When a finding is made, Finnish plant health authorities ask the authorities in the country of origin to investigate the situation there and take the necessary measures to ensure that contaminated matter is no longer shipped. Furthermore, the European Commission's Directorate-General for Health & Consumers, which gives priority to the pine wood nematode risk, is notified of each finding. Findings also allow the EU to work towards diminishing the risk throughout its area.

12. What is the ISPM 15 standard and what does it mean?

The ISPM 15 standard is based on an international treaty issued by FAO, the Food and Agriculture Organization of the United Nations. The treaty specifies certain handling requirements for wooden packaging material, which ensure that the pine wood nematode is destroyed and its spread to nematode-free areas is prevented. The treaty requires the use of a certain mark, to indicate that the packaging material producer has complied with the handling requirements.

13. What are the handling requirements specified in the ISPM 15 standard?

Wood used to produce packaging materials must be debarked and heat treated to a core temperature of at least 56 degrees Celsius for a minimum of 30 minutes. To meet these requirements, the mark must include the abbreviation HT for "heat treated". Alternatively, the wood can be gased with methyl bromide. The use of this gas is prohibited in the EU, but it is commonly used in Southeast Asia, for example. If it has been used, the mark bears the abbreviation MB. Additionally, the mark must specify the country code and the code of the producer holding the labelling right. Using this number, a producer that has used contaminated packaging material can be traced in each and any country.

14. To which countries does the ISPM 15 standard apply?

The marking requirement is international and applies to all wooden packages coming from or going to non-EU countries. It does not apply to wooden packaging shipped between EU Member States, with the exception of Portugal, where all wooden packaging material must bear the ISPM 15 mark, even when being shipped to other EU Member States.

15. Is there a charge for pine wood nematode control inspections?

For operators, a pine wood nematode inspection and laboratory examination are free of charge.

16. What would be the consequences of finding the pine wood nematode in Finnish forests?

If the pine wood nematode were discovered in our forests, it would have wide-ranging consequences throughout the country. The cost of statutory prevention and eradication measures would be substantial. Due to our cold climate, extensive tree deaths would not necessarily occur, but the pine wood nematode's presence in our country would hinder Finnish wood exports. Eradication measures would require conifer-free zones in our forests. If necessary, prevention measures would also include garden and park trees as well as nature conservation areas. The financial, aesthetic and ecological impact would be considerable.