6 non-chemical ways to tackle potato blight

The humid weather over the last week has been ideal for potato blight to establish in the crop, with Met Eireann issuing a blight warning.

Gareth Austin, a horticulturist from Co. Donegal, says that late blight in potatoes is a challenging subject for any home and professional grower, and will require a multi-pronged approach.

“Vigilance and understanding the life cycle of the pathogen is vital to control this, and any other disease,” he says.

Austin suggests the following alternative methods to prevent and control blight:

Variety selection

Choosing more blight resistant varieties is the first step, according to Austin.

There has been great strides made in research on varieties, and the Sarpo varieties are a great range to get yourself into, he says.

“I grow these with schools, as of course we can’t get in to do traditional blight spraying, and when I grow Sarpos there’s always an Autumn harvest for the school.”

Another option when considering varieties is looking at earlies, such as Epicures, which are harvested before any risk of blight, he says.

Crop rotation and hygiene

Employing a rotation plan can prevent or control the spread of blight and rotating crops can reduce pathogenic soil build up, Austin says.

Blight is a pathogen, so is easily spread by dirty tools, boots, hands etc. so good hygiene of the equipment and in the area is important, he says.

Removal

Removing blighted plants at early signs and burning or disposing off site.

Fertility management

Ensure that adequate K is available for crops and soft growth is also prone to blight, Austin says.

N is available late season and not as a big flush at the start; this is more susceptible to contracting blight, he says.

Fresh air

According to Austin, blight likes damp foliage and stagnant air.

By planting ridges in the direction of the prevailing wind with spacing between rows you can reduce the likelihood of blight occurring in the crop, he says.

Spraying

Austin says to use a copper octanoate based spray, on potatoes you can spray up to 12 times and it will still be organic.

Also when watering, Austin advises against getting the crop too wet during watering.

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