A Tesco representative told Horticulture Week: "These are vicious rumours started by a garden centre. We had one batch that was tested and what was found on it was found not to be a harmful whitefly. It was just something in one store."
He declined to name the particular supermarket. Tesco has also said that poinsettia sales are up 22 per cent year-on-year.
Meanwhile, the NFU is believed to be requesting a specific off-label approval for poinsettia pest and disease solution nicotine shreds, which are being withdrawn from the market.