New rules on plant health, designed to stop diseases spreading or jumping borders, will become effective on Saturday.
The EU Regulation 2016/2031 on protective measures against plant pests was steered through the European Parliament by UK member Anthea McIntyre, Conservative MEP for the West Midlands.
It became law in December 2016 and is directly applicable in all EU countries from December 14.
Miss McIntyre, Conservative spokesman on both agriculture and the environment, said: "Plant disease can have a devastating effect commercially, on biodiversity and the environment generally, so it was vital that we should make ourselves ourselves more resilient.
"In Britain we were taught in the most direct and damaging way by Ash Dieback.
"But it is also important to remain practical and to try not to over-burden the growers, importers, dealers and retailers who will have to make the news rules work. I believe we have got that balance right."
The new regulations will mean more-effective protection, with greater focus on specific pests. New requirements will cover the movement of plants, both in and out of the EU and within the bloc.
The new regime includes revised quarantine rules, wider application of the phytosanitary certificate regime and so-called plant passports, introduction of the concept of "priority pests" to target urgent cases, and outright bans on plants and products deemed high risk.
Growers and plant-trade professionals will have to register and will be obliged to notify the authorities of any pest found - then take immediate precautions to prevent its spread.
Miss McIntyre said: "The new regulation repeals seven previous pieces of law and brings all the relevant legislation together in one place, so that should help make understanding simpler.
"It will mean some more responsibility and obligations for professionals in the field, but they do have to be our front line in this battle. Without that the danger is that the whole industry can be undermined at huge expense to everyone."