Farmers’ weapons of mass destruction carry cancer fears

Clasping the stem firmly with both hands, I tug up fronds of bracken shoot by shoot. The last, buried inches leave the ground so sweetly that it should be quite a satisfying task.

What spoils it is knowing how little it achieves. The stem parts without protest from an underground cabling of tough, black roots – a single plant of bracken can eventually spread to fill a whole field. Only cutting it year after year will eventually wither its vigour.

My token tugging of the fern as it creeps in from the hedge is the reflex of a gardener, now rather less vigorous than it was. But for many hill farmers, watching green waves of bracken roll down the higher slopes of land, its invasion can seem a last discouragement.

Bracken hides sheep that burrow after the last strands of grass. It holds ticks that can carry diseases, for both sheep and humans. It sheds toxic spores that can pollute hill streams and piped water with carcinogens. And where it finally shades out the grass a farmer must deduct the area from the grazable land that earns the European Union’s basic farm payment.

How many birds can the natural world support?

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Pioneering plants in peril on shingle banks

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A bunch of 10 wild roses by any other names

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We’re all lost without a national landscape map of Ireland

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Roundup has been the farmers' regular weapon of mass destruction on everything from hillside bracken to weeds in fields of grain due for harvesting

Ironically, fear of a cancer hazard has also been holding back final EU approval of asulam, the one selective herbicide that kills bracken, roots and all. It was banned originally through concern about the chemical’s safety when used on edible crops.

This year, following “emergency” authorisation of its sale by the Department of Agriculture, it can be used on bracken from July to September. Much of the invaded land is too steep for spraying from tractors or even manually from knapsacks, and aerial spraying is long banned by the EU. That is, in any case, a costly operation. Even without it, a 5l can of concentrated Asulox (the brand name) costs €100.86.

Some blankets of bracken on our hillside seem to have trebled in size. That goes, too, for dark thickets of rushes, flourishing ever more densely on damp land as climate grows milder and wetter.

Left undisturbed, a clump of rushes can grow more than a metre high. They flower this month in tufts that can produce more than 8,000 seeds per shoot. And now the herbicide MCPA, commonly used for rush control, is toxically contaminating water supplies and may invite an EU ban in its turn.

Along with rushes, MCPA can be used on ragwort, docks, thistles and nettles. A map published in the Irish Farmers' Journal last month showed pesticide contamination of water schemes county by county in 2015.

These pesticides are now shown definitively to damage honeybees and bumblebees at every stage of their lives

Sampled for Irish Water by the Environmental Protection Agency, polluted schemes had more than doubled from the previous year, with the highest rate in Co Mayo. Two-thirds of 61 schemes held MCPA. As Irish Water has been telling farmers, just one drop can contaminate an Olympic-size pool.

All this coincides with the row about glyphosate, key ingredient of Roundup, Monsanto’s all-purpose herbicide. A million or more EU citizens, it is claimed, have signed online petitions against further approval.

Roundup has been the farmers' regular weapon of mass destruction on everything from hillside bracken to weeds in fields of grain due for harvesting. World Health Organisation researchers have termed it "probably carcinogenic", generating fierce argument between environmentalists and Monsanto chemists.

Residues of the weedkiller are commonly found in bread and human urine, and a final judgment on its use in food crops is soon expected from the European Food Safety Authority.

And then there are neonicotinoids – “neonics” to the trade. These pesticides are now shown definitively to damage honeybees and bumblebees at every stage of their lives. An exception, it seems, may be where farmers grow enough pristine wild flowers, to give the bees an alternative, around their flowering but toxic oilseed rape.

This appears to be so in Germany, whose bees, in recent field trials, were spared the harm of those on farmland across the UK and Hungary. This major research was mostly funded by the pesticide manufacturers themselves, having rejected evidence of harm gained through laboratory tests.

The target pests of neonics are aphids, suckers of plant sap and sometimes with toxic saliva. A new Bayer insecticide, acting on aphids in much the same way as neonicotinoids do, is flupyradifurone, a chemical that also permeates the plant and its pollen and takes months to disappear in the field.

Claims that this is "safer for bees" are challenged by environmental groups, and although the chemical has been authorised by the European Commission, online petitions were launched last year against its approval by the Department of Agriculture's pesticide-control service.

The rules around using pesticides grow ever more substantial, at least on paper (and online). An EU sustainable-use directive now requires every farmer or contractor using a sprayer to register with the Department of Agriculture as a professional user and sign up for proper training. Especially, one hopes, in leaving adequate "no spray zones" around rural waterways and wells.

Michael Viney's Reflections on Another Life, a selection of columns from the past four decades, is available from irishtimes.com/irishtimesbooks; viney@anu.ie