Not thought to be correct.
In UK climate, the sun is unlikely to raise the temperature under even a black polysheet to the required temperature to sterilise a soil profile, many organisms are mobile and can retreat.Similarly, a buried seed cannot (unfortunately!)be killed. If youve ever visited a forest fire site after the first subsequent rain, you would realise nature will return.
I would not personally lay any plastic as a long term remedy, but it can be a useful control tool.
