I'm swinging both ways on this one. Seems convenient to overlook we've had fire-blight on hawthorns in
Melbourne for some (unsure how many) years. If you can prove that the restrictions you want to enforce are genuinely there to protect health, hygiene, the environment or a few others I can't remember and not just a industry protection measure/tariff by another name, then the WTO can't stop you. Unfortunately Australia could not demonstrate that and hence were told the ban had to go.
If strict hygiene is followed then there shouldn't be a problem, however I reckon money and time being what they are, sooner or later someone will slip up. My bigger issue is importing fresh fruit from overseas. That seems a real waste to me. If public attitudes about that and eating whats in season and local changed...