[brownp]

I returned from my holidays today and visited my allotment to find my main crop in a sorry state.
Most plants are either completely dead above ground or wilting badly with discoloured leaves
I dug up two plants - 1 dead and one yellowed. The tubers are covered in brown craters - they don't look appetising. I've cut one open - it seems to have only affected the surface.
Does anyone know what it is? Should I harvest them all now or can I leave them for a few days. Finally - are they ok to eat?
thanks
Phil

[mumofstig]

Are the craters just rough pitted areas on the surface?...If so it is scab and can just be scraped, or peeled off. It's a common thing, and nothing to worry about.

It's very difficult to be sure without seeing a pic of them though

[brownp]

Thanks for that - I've looked at other pics - i think it is scab.
Phil

[MoreWhisky]

An old boy on our site has told me scab on spuds is caused by using tap water to water them.

I dont know if this is true or not tho, anybody know for certain?

[mumofstig]

You can get scab without using tap water, whether it would cause it or not....dunno

[Mash Mad]

sounds like scab. it can be caused by not giving your potatoes enough water i suffered a bit this year and come to think about it i did'nt really start watering daliy until later on in the year.

i gave them 2 watering can fulls a day when they were bigger but i suppose i should of given them one when they were smaller.

next year im going to pay more attention to them.

just peel of the scab and they will be fine to eat   

[loam ranger]

Scab is sometimes caused by alkaline soil ie liming the plot before pots are planted. some of my spuds have scab on them  I spread lime on the bed where the potatoes are growing :
Geoff

[Wombat18]

Some people recommend a sulphur treatment to reduce scab.  It's fairly expensive for something that's just cosmetic, however.

[WirralWally]

Scab is just an infection on the skin of the potatoes and it will not normally have any effect on the flesh.
There are two types of scab. Common scab and powdery scab.
They can be caused during both extremely wet and extremely dry conditions.
Certain varieties of potato are resistant to one or both types of scab.
Trying to prevent it is a work of art (coupled with a large dose of good luck).

There is a wealth of information available on the ‘net concerning the causes and prevention of potato scab. If you can understand and follow all the guidelines then you may achieve some degree of success.
If you are misguided enough to think that the solution is to do with the use of tap water or limited to the level of lime in the soil then you’ll be sadly disappointed.
Potato growers have tried and failed to eradicate scab for a long time.

My advice to you is to research the subject; take onboard the advice that appears sensible, and hope for the best.

For certain you need to practice crop rotation; maintain an even moisture level; regulate the soil acidity; ensure that any manure used is well decomposed; and, very importantly, only grow varieties that show good scab resistance.

If you do find a way of getting rid of potato scab completely then you should share the secret with the rest of us and, maybe, we could patent it.