Industry figures indicate that the countries' vast expanse of agricultural land should not provide serious competition for years.
"They're going to be too busy getting their houses in order to worry about exporting," said James Ede at the NFU's Brussels office.
Romania is more advanced in organics than Bulgaria and has 75,000 ha certified, while Bulgaria has 13,000 ha. "We'd expect to see huge take-up, as when Poland joined," said Amajt Sahota of Organic Monitor. "But don't expect the same crops as in the UK. It's likely to be cereals, rather than horticulture."
A Defra spokeswoman said accession provided an opportunity for UK growers to export produce and expertise. "Farmers in the new member states still struggle with lack of capital, inadequate transport infrastructure and the need to comply with EU standards."