At least 10 per cent of Irish mushroom farms have closed down since the UK referendum decision to leave EU, the Dáil was told.
Sinn Féin TD Caoimhghín Ó Caoláin said a minimum of six of the 60 growers operating at the time of the June vote had ceased production.
He said 80 per cent of Irish mushroom production was destined for the British market.
The sector is worth €180 million a year and employed 3,500 people across rural Ireland but is in a very serious crisis, he warned.
The decline by about 20 per cent in the value of sterling was having a devastating effect on producers and processors in Ireland, he said.
Mushroom growers found themselves in an “impossible situation”, not least because of fixed forward contracts set in sterling.
They were also competing with the “ever-hungry eyes of producers in eastern Europe eager to carve out an even greater share of the British market,” Mr Ó Caoláin said.
The TD said it could “spell economic calamity for these producers and their employees, families, communities and local economies and for Ireland’s export earnings”.
Minister of State for Agriculture Andrew Doyle acknowledged the mushroom sector was particularly at risk because of its dependence on UK markets.
He said this week the Government arranged for the payment of just under €1.57 million to one of the mushroom producer organisations under the EU producer organisation scheme.
Mr Doyle said grant supports would be prioritised by Bord Bia through its recently launched marketing intensification programme to provide supports for companies with high dependency on UK markets.
It is aimed at producers with turnover of between €1 million and €30million, but with a fund of €500,000 eligibility would be competitive with 20 to 30 firms expected to be supported.
The Minister said the Department of Agriculture had established a dedicated unit to consider the impact of Brexit.
But Mr Ó Caoláin warned that while Article 50 would not be triggered until next year “the reality of the crisis facing the mushroom industry is immediate.
“The producers cannot wait until March 2017.”
The Minister told him that UK customers had a choice to make on “do they want this fresh product from Ireland for which there is no question about standards, quality and reliability or do they want to push it over the brink”.
