[SnooziSuzi]

Every year when I harvest my potatoes they are covered in various degrees of scab.

An allotment neighbour of mine says it's caused by rainwater on the potatoes which is why he only waters from the mains water 

My allotment is much further down a slight slope than his, and the whole allotments are built on an old ash pit where the ash from the coke fires was dumped years ago.  the area was covered over with a thin layer of soil (a couple of feet thick in rare places, a foot or less in most) and was turned over to allotments.

I heard that an acid soil will cause scab, so I am wondering if there is anything I can do to lessen it in my soil and is the rainwater theory plausible?

[Nikkithefoot]

I guess if it was rainwater that caused scab then the commercial growers would have a major problem!!

I am led to believe its the ash that can cause the scab. I once put a row of spuds through where I'd had a bonfire and the scabby spuds were where the bonfire had been.

[SnooziSuzi]

I think that sounds like the best answer Nikki,   I think maybe for next year and every year after I'll dig out as much of it as I can from the bed they're going into and replace with manure; the spuds'll love that!

[daisy1990]

some types of potato are more resistant to scab than others, so it may be worth while getting seed potatoes from a different type?

[DD.]

I heard that an acid soil will cause scab?

It's quite the opposite, it's worse on alkaline soil, which is why you should avoid growing where you'ce had heavily limed brassicas the previous year.

The RHS have a good fact sheet on it.

http://apps.rhs.org.uk/advicesearch/Profile.aspx?pid=230

[sunshineband]

Strange idea about the rain water, surely?

Does he cover his crop to prevent it getting any rain d'you know?

[DD.]

Some of the OB's really do have strange ideas. Make you wonder where they get it from!

[sunshineband]

I reckon it's like a sort of initiation test .......

...... or maybe a competition amonst them as to who can get the new guys to do the silliest thing 

Some previous threads have had some really whacky things in them