The Association said failure to control grey squirrels on top of the spread of several new serious tree diseases - notably Chalara Fraxina and Acute Oak Decline - will hinder any young woodland's chances of surviving until maturity.
CLA President Henry Robinson said: "The grey squirrel is an invasive alien species which poses a significant threat to woodland in the UK, particularly in the face of several new and serious tree diseases.
"Currently the most effective method of control is the use of Warfarin-based bait. Without it, any attempt to control the species is almost impossible."
Warfarin is currently allowed to be used in the UK until 31 July 2016 with applications for the re-approval of the substance due to be submitted by 31 July 2013.
However a fee of £500,000 demanded by Sweden for each application resulted in no applications being made for the re-approval by the due date - a new expiry date has been proposed for 31 March 2014.
Mr Robinson said: "A fee of £500,000 to submit an application for the re-approval of this substance is wholly disproportionate to the sales of Warfarin-based formulations for the control of squirrels."