The letter stated: "Whilst the UK’s off-label system has gone some way to addressing it in the past, more substantive steps are now urgently needed at EU level."
The EU's previous failure to take action on the issue has left UK growers "at a competitive disadvantage compared to those in the US, Australia, New Zealand and many emerging economies", it warned.
To make up for this, the EU should consider emulating the US government's IR-4 Project, it said. Established nearly 50 years ago, IR-4 works to support registration of pest pest controls in fruit, vegetables, ornamental plants and other speciality crops.
The letter concluded: "The UK’s farmers and growers now look to the UK Government to take a leading role in ensuring that action at EU level is both prompt and substantive."
NFU Scotland specialist crops spokesman Russell Brown explained the issue is currently being investigated by the EU’s Directorate for Health and Consumers (DG Sanco).
But he added: "Of the options being looked at, only stronger EU support to establish a programme on minor uses and speciality crops would deliver a more permanent solution."