(May 6, 1:28 p.m.) The U.S. and Canada have agreed on a new protocol to deal more effectively with future outbreaks of potato cyst nematodes.

Officials are optimistic the change will limit trade restrictions placed by one country on the other because of an outbreak, according to a U.S. Department of Agriculture news release.

Under the new protocol, dirt from fields in Canada and the U.S. that produce seed potatoes will need to be sampled using a full-field grid pattern. That replaces a protocol in which only the perimeters of fields were sampled.

In addition, all potato shipments between the two countries must include a phytosanitary certificate stating that the shipment originated from fields tested and found free of potato cyst nematodes.

In 2006, the U.S. banned potato imports from Quebec because golden nematode pests had been found on spuds slated for export. Also in 2006, Canada banned potatoes from Idaho, where potato cyst nematodes had been found. The bans were lifted later that year.

The pests pose no health threat to humans, but if left untreated they can cause significantly affect yield.

The new protocol comes a year after the U.S. and Canada agreed on a certification protocol to prevent the spread of nematodes across the U.S.-Canadian border.

Under that 2006 protocol, all seed potatoes traded between the two countries are tested for nematodes.