The grains for which a phytosanitary certificate is required are wheat, rye and wheat/rye. The legal requirement is that importers of these grains from Afghanistan, India, Iraq, Mexico, Nepal, Pakistan or the USA must register with the Department and must inform the Department of the arrival of such grain. The wheat must be covered by a phytosanitary certificate and it is subjected to phytosanitary inspection at the point of entry to the European Union, or nearby. Similar requirements apply in all other member states.
I am not aware of the arrival of any wheat direct from any of the countries listed. Ireland and other EU member states accept phytosanitary certificates issued by third countries except where there are grounds for not doing so. It has not been necessary to reject phytosanitary certificates from any of the countries listed above.