HTA, which drafted the amendment with the Crop Protection Association, is urging all members to write to their local MEP by email before Monday (12 January).
The NFU is also calling on growers to email MEPs to support Robert Sturdy's amendment before the EU vote on pesticides on Tuesday (13 January).
On 12 January the European Parliament will debate the proposals for a Regulation on the Placing on the Market of Plant Protection Products and the Sustainable Use of Pesticides directive.
The HTA stated: "We are asking you to support Robert Sturdy MEP's amendment calling for a thorough and wide-ranging EU-wide impact assessment of all the Regulation's aspects including cut-off criteria on all industry sectors affected, including agriculture, horticulture, gardening, landscaping and public and private amenities."
MEPs contact details are at http://www.europarl.org.uk/uk_meps/MembersMain.htm.
For an up-to-date briefing on writing to MEPs people should check the HTA web-site.
Other background information can be found on the NFU website.