ISPM-15 Explained

May 2025 Edition:

by: Justin Brown, ACE

The pine wood nematode is a wood-destroying organism native to North America.  Though most native pine species are resistant to its effects, the pine wilt disease it causes is widely considered to be the most destructive forest disease worldwide. The damage only increased as global trade expanded. 

Pine wilt was first introduced to Japan in 1905. By the 1970s it was responsible for the loss of approximately 2.4 million cubic meters of forest area annually.  However, it was killing off 50 million cubic meters per year from 2004 to 2014.  It is estimated to have caused 8.4 billion won worth of damage in S. Korea and has cost European nations an estimated 22 billion euros. Forecasts show that up to 34% of the forest in Europe could be impacted by 2030.

  Though the pine wilt nematode is one of the more destructive organisms, it is still only one of the countless insects, fungi, and other parasites that infest wood and wood products.  That is why, in 2002, the International Plant Protection Conference (IPPC) implemented the International Standards for Phytosanitary Measures 15 (ISPM-15).  Since the inception of ISPM-15, more than 170 countries have signed on to the program which aims to reduce the introduction and spread of quarantine pests in raw wood.

Most, but not all, wood products are covered under ISPM-15.  The regulations apply to any wood packaging materials (WPM) that haven’t undergone sufficient processing to kill any pests that may be present.  These materials include crates, boxes, dunnage, pallets, cable drums, and wooden spools or reels.  Any lumber that is less than 6mm thick does not require treatment.  The same goes for processed materials like plywood and particle board.  Likewise for anything that is heated during manufacturing, like barrels.  The rules also don’t apply to sawdust, wood shavings, wood wool, or any components that are permanently attached to containers or trailers.

The ISPM-15 program has 3 parts.  The first is the regulatory body which consists of agencies called National Plant Protection Organizations.  These agencies are responsible for the authorization and supervision of treatment providers.  The second aspect is the pre-shipment treatment of the wood packaging materials. The third and final feature is the ISPM-15 mark.

There are three approved treatments for WPM.  The first is a heat treatment with steam or in a kiln.  This requires the materials to be heated to 56C for at least 30 minutes with the temperature monitored at the coldest spot.  These heat chambers must be inspected and approved by an NPPO.  The second treatment uses dielectric heating.  For these treatments, the wood must be heated to 60C for at least 1 min.  The third treatment type is fumigation with methyl bromide. All treatments require the wood to be debarked prior to shipment.

Methyl bromide is a fumigant that was once widely used but has been restricted to specific quarantine and pre-shipment uses in most countries.  To use methyl bromide in an ISPM-15 treatment, the wood has to be at least 20cm thick and must be debarked prior to treatment.  The treatment itself must last a minimum of 24 hours with a target concentration time that varies depending on temperature (Tables 1 and 2).  The protocols require specific reading times with concentrations taken at two, four, and 24 hours at a minimum.

The mark is a crucial part of the ISPM-15 program.  Many WPM will be reused and reshipped multiple times and the mark is the only way to indicate whether the products conform to the regulations.  Every mark consists of the IPPC symbol, a country code, a treatment provider code, and a treatment code (Examples 1-6).  There are three treatment codes: “HT” for heat treatments, “MB” for methyl bromide, and “DH” for dielectric heating.  The mark is recognized by all member countries and must be applied to all treated materials. 

Like any program intended to control pest infestations, ISPM-15 isn’t 100% effective.  Studies show that WPM entering the US from 2005-2006 showed a 36-52% reduction in infestation rates.  There are many possible explanations for these results.  It is possible that some pests have developed a tolerance to the ISPM-15 treatments.  In this scenario, some number of pests would survive the treatment.  It is also possible that some materials are being reinfested after successful treatment.  Finally, it could be an issue with the treatment itself.  Issues such as unintentional noncompliance or fraud could result in insufficient treatments or materials being shipped without being treated at all.

In the future, it is believed that the industry will move away from methyl bromide treatments.  Methyl bromide is an ozone depletion and a greenhouse gas.  With that in mind, the IPPC has a preference for heat treatments and may be phasing out the use of methyl bromide for pre-shipment fumigations.  The IPPC has considered using sulfuryl fluoride as an alternative to methyl bromide.  While sulfuryl fluoride is currently approved for other phytosanitary treatments, it is not yet permitted for ISPM-15 fumigations.

As our world becomes more interconnected, it is imperative that steps are taken to limit the spread of non-native species that can damage ecosystems and limit biodiversity.  ISPM-15 is a vital tool in combatting the proliferation of these invasive species.  Though the specific methods may change in the future, any changes will be aimed at protecting the environment for future generations.