For example, farmers with arable land above 15 hectares must set aside at least 5pc of their land as EFAs, by leaving it fallow or allowing hedges and trees to grow, for instance.
In a statement tabled at the meeting, the 18 countries said they had "deep concerns" about the pesticide ban on this type of land, as well as additional rule changes on crop rotation.
They say the Commission's changes would increase farmers' costs and "could imply that farmers are no longer so keen about these types of EFA".
And they allege that tying a pesticide ban to EU subsidies instead of inserting it in rural development legislation (known in EU jargon as the CAP's second pillar) amounts to backtracking on previous commitments.
'CAP Greening is a Failure'
The European Environmental Bureau criticised their arguments, saying that the "demand on taxpayers to pay farmers to spray pesticides" shows that CAP greening is a failure.
"It is shocking and shameful to hear 18 member states claim that using pesticides on crops grown in areas set aside for nature protection will actually bring about environmental benefits," said the EEB's policy manager for agriculture and bioenergy, Faustine Bas-Defossez.
Meanwhile, the EU is still fighting over how to regulate pesticides in organic farming.
EU negotiators are no closer to agreeing on whether to introduce upper limits for organic food or feed that has been contaminated by pesticide residues from neighbouring farms or in transport.
New GM row brewing in Brussels
Another crop-related row has sprouted over genetically modified (GM) products.
MEPs have shot down EU plans to approve the authorisation of three types of GM maize and a glyphosate-resistant cotton, creating difficulties for the bloc at a sensitive time.
The parliamentarians - among them Sinn Féin's Lynn Boylan - say the products produce a toxin that could harm butterflies and moths, and contaminate other crops.
Organic farming groups say GM products jeopardise their produce, a €24bn market in the EU that is growing at 7.4pc per year.
While the European Parliament has no power to veto GM approvals - that is done by an EU expert committee, as is the case with pesticides - the move has unearthed a long-running fight about who should bear the political responsibility for chemicals authorisation.
This is the fifth time in a year that MEPs have opposed GM authorisations. And under new rules that came into force last year, individual EU countries can restrict or ban the growing of GM crops on their territory (but not the import and sale of GM products). So far 19 countries - not including Ireland - have done so.
MEP clune makes case for tillage farmers
Fine Gael MEP Deirdre Clune followed her party colleague Mairead McGuinness in making the case for struggling grain farmers.
She called on EU agriculture chief Phil Hogan to step in to support farmers who have been hit by difficult weather conditions.
The Irish Farmers’ Association says tillage farmers are looking at losses of around 100 million euros this year.
The EU’s €500 million aid package earlier this year promised aid for several sectors but is geared towards dairy.
“All across the country, many tillage farmers are facing into the reality of heavy crop losses following a very difficult spell of weather around harvest time preventing them from harvesting crops this year,” Ms Clune said.
“It is time that the government, assisted by the European Commission, stepped in to help struggling farmers.”
The end is nigh for invasive aliens
New rules to protect native European crops and plants from being wiped out by alien pests are close to being finalised.
After more than three years of fighting over import bans and EU compensation for producers affected by pests, a European Parliament vote later this month will finally seal the deal.
The new rules — applicable from 2020 onwards — bring in import bans for species on a “high-risk” list and mandatory “plant health certificates” for low-risk plants.