Potato scab

[Henwoman]

Unfortunately, I seem to have scab on some, but not all, of my potatoes this year. They are Charlottes which I planted on 3 April. Any ideas about what to do to avoid it next year. This is a potato bed where I always grow them. I know I should rotate beds, but never have and have never had problems previously. Help please!

[Annpan]

scab is caused by a fungus I think so I would guess it stays in the soil and so rotating is probably a good idea anyway.

My expert book says to dig in compost but don't lime.

I know it is unsightly but it can be peeled off and the flesh is fine (I know not great for new potatoes but still)

[Millymollymandy]

There's another thread about scab running at the moment - it's caused by being too dry. Mine always have scab to a lesser or greater degree so the answer is to get seep hoses on your potatoes as soon as you've finished earthing up and peg them along the top of the ridge so the water seeps down right to the roots. If you don't get enough rain it's practically impossible to wet something that's been earthed up when the moisture needs to be a good 8-12" down.

[Odsox]

The traditional way to prevent scab was to fill the trenches with fresh grass cuttings when you plant them, and then earth up as normal. That way you keep moisture right where it's needed.

[pumpy]

Potato scab is generally caused by a combination of dryness & too much lime content in the soil. Maybe a good dollop of peat-based compost would do the trick next year?

[Millymollymandy]

I don't think there's much lime in the soil in Brittany as it tends towards the acidic although mine is neutral. I reckon for Henwoman it's the drought although she lives in a much wetter part of Brittany than me which is why I have it all the time (even a bit with the seep hoses!) and she's never had it before!