Fungicide bans the major blight on potato industry
The loss of blight control fungicide groups through regulation poses the biggest single threat by far to the potato industry, and risks leaving the economics of growing the crop on a knife-edge.
That was the message to growers at a potato conference yesterday by independent consultant Denis Buckley, of Highfield Lodge Agronomy, who said that the industry faced increasing challenges as the armoury of pest and disease control measures continued to fall to regulatory attrition.
And he said that farmers in the UK and the rest of Europe had been waging a 175-year battle against the fungus-like disease Phytophthora infestans, which causes blight ever since it had been identified as the cause of the Irish potato famine, a major catastrophe which saw millions either starve or emigrate.
But while fungicides and potato varieties resistant to the disease had averted such calamities in recent decades, he said the disease had an astonishing ability to develop its own resistance to sprays and other treatments while overcoming that of new potato varieties.
This meant that without constant development – including the use of procedures such as CRISPR DNA editing to unlock more resistant potato varieties – the threat was everpresent. “And this arms race simply isn’t being helped by the constant loss of active ingredients used in its control,” said Buckley who was highly critical of the UK’S expert committee on pesticides which advised the government on its decisions: “For, with perhaps a couple of exceptions, there are no experts on pesticides on the committee!”
But he said that in the modern world food was abundant and long as that was the case the political regime would continue to remain brutal on the licensing of pesticides – which would inevitably put even more pressure on the few ingredients which remained.
“However,” he said, “if a crop disease like blight gets the upper hand and does lead to a major crop failure leading to a shortage in any of our staple foods, then there’s no doubt that there would be a sudden change in attitude.”
The conference heard that across the whole cropping sector there had been 987 different active ingredients available to control pests and disease back in 1983 but that had fallen to fewer than 440 – and with more likely to be deregistered the figure could tumble to as few as 150-200 in the near future.
The reduction in the availability of sprays was also biting into other areas of potato growing – and now that diquat could no longer be used for pre-harvest haulm destruction, growers were facing up to the challenge of this previously straightforward task.
However Ed Hodson of potato machinery manufacturer Grime said that there had been considerable innovation in this field. On top of flailing – likely to become the commonest method of destruction – other methods being investigate included electrocution of the haulm, burning with propane gas, root cutters, steam and even the use of kitchen salt.
“But although many of these approaches might be reasonably effective, many of them are very energy intensive and will add considerably to the both cost and the crop’s carbon footprint – while the effect on quality and shelf life of the potatoes has yet to be seen,” said Hodson.