potato blight

by Mary
(SW Scotland)

I have potato blight and have cut all the green off all affected and unaffected plants so there are just very small bits of the plants left showing. I have dug up 3 roots so far and none seem to be affected by the blight. How long can I leave the rest of the potatoes in the ground as being "new" spuds they will not store well?

Comments for potato blight

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Sep 11, 2010

Potato Blight - leaving unaffected plants in ground
by: Megan

Late blight is a nasty fungal disease, as the potato growing Irish found out in the 1840's. Late blight, cause by the pathogen, Phytophthora infestans, affects potatoes as well as tomato plants. With spuds, the symptoms are first noticed in the leaves, then the stem and tubers rot and die. Warm to cool, wet and humid conditions encourage the pathogen's growth and spread.

Early blight is a fungal leaf spot disease, caused by Alternaria solani, or Septoria leaf spot. Early blight affects the leaves of plants and does not cause fatal damage.

If you have potato late blight, it is essential that you check and keep checking to see whether you really have got rid of all plants affected. The spores can travel easily, and will soon multiply, especially if the weather conditions are right.

Leave the remaining spuds in the ground to keep growing, but any sign of speckled browning on the leaves, pull up the plant and dispose of safely (burn, hot compost, seal in rubbish bag or bury at least 2ft under).

You should also mound up the earth around your potato plants to stop any floating spores from getting down into the tubers. With enough earth between any spores and tubers, the spores should die, or at least give the tubers time to grow bigger with skin tough enough to resist being infected.

Any spuds dug up, although seeming blight free, are fine to eat, but should not be used for seed potatoes next season. Buy a virus resistant strain and practice crop rotation if possible.

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