prohibition of ornamental plants larger than 18 inches in march 2010 costa rica referred to the us restrictions on the importation of ornamental plants larger than 18 inches based on the us code of federal regulation section 37 part 319 title 7 7 cfr 319.37 . costa rica reported that in early 2000 it had conducted a risk assessment to support its request for the united states to lift its restrictions. based on a us request costa rica had established and operated a clean stock program aimed at reducing the number of interceptions of exports of ornamental plants to the united states. the clean stock program for dracaena marginata started to operate in 2005 and it involved authorities from costa rica and the united states. the program concluded its work in december 2008. however more than one year after the conclusion of the program the united states had not yet initiated a process to modify its regulation restricting the importation of ornamental plants larger than 18 inches. a working plan had been elaborated by the regulatory agencies of both countries nevertheless costa rica was concerned that despite the agreement on the technical issues of the plan the united states was taking too long to revise its restrictions. the united states reported that the authorities of both countries had been working cooperatively on issues related to the importation of tropical foliage particularly dracaena spp.. the on-going work addressed the development of greater surveillance and inspection protocols to reduce the high number of interceptions. the us department of agriculture usda was working with costa rica on a work plan and a proposed rule to allow the safe entry of oversized dracaena spp. to complete the science-based review process the usda was awaiting a response on the draft work plan by costa rica so as to expand the current clean stock program. in july 2012 costa rica reported that its specific trade concern on the prohibition of ornamental plants larger than 18 inches no. 292 had been resolved following the publication by the united states of a modified regulation addressing the concerns of costa rica. the united states thanked costa rica for its outstanding co-operation and collaborative efforts in resolving the concern.