Saturday, 20 August 2016

Potato blight: what to do

The dreaded splotches
We live in an area where potato blight (officially known as late blight) is a common problem and, sure enough, our maincrop potatoes have been affected again this year. However, that is no reason not to grow maincrop potatoes. The following are good preventative measures:

  • Use certified seed potatoes with high blight resistance (Sarpo range or Setanta).
  • Start early in the season (if you sow early the tubers should already be a good size when the blight hits).
  • Grow some extra since the final tuber size might be smaller than expected.
  • Practise crop rotation.
  • Remove any rogue potatoes that pop up from the previous year's crop and avoid composting potato peelings.
That's all the plants removed from the tattie patch

From July onwards, watch your potato plants like a hawk. Ideally, monitor them daily. If any of the tell-tale brown splotches appear, act straight away. Don't wait for all the plants to become affected. The tubers will be fine if the foliage is removed immediately; they just won't grow as big as they would have otherwise.

If blight strikes:
The burn pile
  • Cut down all potato haulms (or shaws, as we call them in Scotland).
  • Burn the foliage.
  • Cover the potato patch with mulch or earth up and leave the tubers in the ground for three weeks (this allows for the skins to harden and the fungal spores to die off).
  • Regularly inspect your stored potatoes for any sign of rot.
Setanta maincrop - the tubers are fine

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