International Standards for Phytosanitary Measures No. 15 require all solid wood packing material to be heat treated and stamped with an official mark. ISPM 15 requirements apply to all hardwood and softwood (coniferous and non-coniferous) packaging materials including Dunnage. This is to avoid the risk of pest infestation. The crate and wood used require an approved stamp like the example below from an accredited Agency. If at time of export from the US the wood does not have a noticeable stamp it is typically re-palletized on plastic or ISPM certified wood with the required stamp or in the case of FCL container cargo it can be fumigated using Methyl Bromide in which a certificate is issued.