On 08/05/20 09:24, Chris Hogg wrote:
On Fri, 8 May 2020 08:55:54 +0100, Jeff Layman
wrote:

SOT because these were bought, not grown.

I buy Maris Piper a lot because I find them very reliable and they are a
very good all-round potato. Last week, however, a 2.5kg pack was of very
poor quality, with just about all the potatoes showing many of the grey
and brown marks seen he

https://ibb.co/PQBL0zz

What causes this? I've seen it intermittently over the years in many
varieties. Looking at images on the internet suggests it could be
cold/frost damage, but surely potato storage is pretty carefully
controlled, and in particular this winter has been on the mild side.
Also, why is it in discrete, although variably-sized, patches throughout
the potato? Why does the colour vary from grey to brown? If it was frost
damage, surely the whole of one side would show it, rather than bits
here and there.

Unfortunately, I can't remember where these potatoes were grown, as I
threw away the bag they came in. Possibly Lincolnshire, as lots of our
spuds are grown there, but I can't be sure.

Heaven forbid that I should offer any advice on growing veg, but I did
find this https://tinyurl.com/ycdud3vq

I'd wondered about bruising, and had seen pics on other sites, but they
didn't seem quite right. The pic you linked to also didn't seem quite
the same as what i had, but it led me to look again. The picture at
https://extension.colostate.edu/topic-areas/agriculture/blackspot-bruise-in-potatoes-5-612/
shows the sort of damage much closer to mine.

So I guess it was down to bruising caused by rough handling of that
batch of spuds!

--

Jeff