Is the wild potato the key to less fungicide use on spuds?

Science week in Teagasc Oakpark has opened up students minds to the humble spud and the wild potato continued to come up in conversation.

Why? The answer is simply Potato blight, as the wild potatoes found in South America are resistant to blight. Some of these potatoes might not be as tasty or suitable for the supermarket, but they have one very important quality – they aren’t susceptible to blight.

Oakpark is the home of potato breeding in Ireland and while it has successfully bred many different breeds, potato blight remains the big threat to the industry.

Fungicides are an essential part of potato production in order to control blight. The aim is to make the sector as sustainable as possible by reducing the amount of fungicides applied.

Common scab is now controlled by irrigation. Cultural methods are used to reduce disease instances like rotation. Control of volunteer potatoes and pests are tested for before planting in fields.

Steven Alexander, a horticultural advisor with Teagasc, made the point that farmers are providing what the consumer demands – a completely blemish-free potato with no marks or rough skin.

Denis Griffin, a Teagasc research officer with Teagasc , stated: “One of the big pressure points for potatoes is still late blight. We have to spray the susceptible varieties 12-15 times.

One of our major goals over the next few years is to try and introduce resistant genes from wild species for late blight and reduce the amount of pesticides we have to use.

The breeding process

However, these wild potatoes are difficult to cross in a natural selection process. Natural breeding takes about 15 years and it might not result in the right potato at the end of the process.

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Denis Griffin addressing the attendance at Potato Day for Science Week in Teagasc Oakpark

Griffin went on to explain that potato breeding is incredibly difficult and time consuming.

“Potato seeds are tiny. We produce a tuber and it is planted in the field. It’s only when its grown in the field that we get to see things like poor skin, poor shape and low tuber numbers. We begin to select out varieties, at this stage, based on the ones that look best in the field.

“We produced 100,000 seedlings and four years later we’re down to 4,500. That’s a huge amount of genetics we’ve thrown away. Adaptation is a huge thing as well. One of the varieties that was taken out might have performed better in France than here in Ireland.

It can be quite random at this early stage of the programme. We try to reduce a certain amount of that randomness by using DNA technology.

Griffin continued: “We try and identify a range of traits in varieties at an early stage, but it’s still beyond our capability to come back and do it at the very early stages of the 100,000 seedlings.

“We select the best varieties at the seedling stage and hope that the traits that we’re interested in survive to the 2,500 stage.

“We test at this stage by taking a small sample of DNA from each one of these and test for specific resistance against things like late blight and the potato cyst nematode. We can also test for cooking performance,” he explained.

GM experiment

The use of genetically modified (GM) technology has been investigated in Oakpark. GM is much quicker than the natural breeding programme and takes out some of the guess work.

The GM potato trials in Oakpark were a break through moment. They showed that the use of a gene from one type of potato to another can result in a blight-free potato crop with no use of fungicides.

While full results of the experiment, carried out by researcher Ewen Mullins and his team, are still to be released, the results for the industry would no doubt be significant.

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Ewen Mullins making a presentation on the GM potato experiment carried out in Teagasc, Oakpark