Chief executive of the Crop Protection Association (CPA) Dominic Dyer commented last week at a meeting of the Food Chain Group: "There's a need for the UK Government to push Europe for an impact assessment."
He added that there should be some kind of control on how the impact assessment is carried out - perhaps in the form of a committee overseen by France, which is presiding over the proposals until the end of the year.
The letter, explained Dyer, would contain an appendix to be signed by all members of the Food Chain Group so that Downing Street "knows who is involved".
The food chain stakeholders will also send letters to the Conservative and the Liberal Democrat MPs to ensure cross-party support for their campaign.
The proposals are due to go to the European Parliament for a second reading later this month. The final (plenary) vote is likely to take place by the end of the year.