From Craig Regelbrugge at ANLA:
USDA’s Animal & Plant Health Inspection Service informally indicated to ANLA that they have been intercepting several quarantine pests, notably pathogens, on imports of boxwood (Buxus spp.) from various countries.
They are exploring restricting Buxus imports worldwide unless and until risk assessments are conducted and appropriate mitigation measures are put into place.
They may make an exception for Canada, but that would depend on Canada’s willingness to take consistent actions with respect to other countries.
Restrictions would most likely affect rooted and unrooted boxwood cuttings.
They could also affect tissue culture, though that is not clear.