[Clover]

Hi
Does anyone know what's up with my potatoes?

They were all looking extremely healthy (9 varieties), although a couple started to get some yellow leaves. 

I earthed about half of them up and the next day several had black drooping leaves especially in the centres.

The discoloration isn't mottled - it's whole leaves, not like blight.

I don't think it's what I've planted them in, as all three beds had different treatments, so far one had shop bought compost, one had my own and one had nothing at all.  there are a few miniature rogue potatoes in my compost which I've missed and I'm picking them out as they appear but they didn't go in all the beds so I'm thinking it can't be a disease.  The potatoes are good, certified ones from Alan Romans.

There aren't any suspicious insects on the leaves, just a few ants.

I'm racking my brains?!?  And here's a theory - the ones I didn't earth up aren't doing it and they were mainly smaller.  It's been extremely dry for two weeks at least and I didn't water at all until yesterday.  Could it be that as the plants have got bigger and the haulms have taken over from the potato seed they cannot photosynthesize because of the lack of moisture?

I just don't know - brown or yellow I could understand, but black seems very dramatic?!

[DD.]

Hi Clover & welcome to the forums, sorry your first post is a sad tale.

If it's not frost, it could be potato blackleg. Yellowing leaves are an early sign of it.

http://www.rhs.org.uk/advicesearch/Profile.aspx?pid=223

[Clover]

Thanks DD, but it really doesn't look like Blackleg to me because the stems don't appear affected at all.

I did consider frost, but I'm told there hasn't been any - I seem to remember reading a discussion here about the possibility of frost if the forecast indicates 6 degrees or so at night because it's measured at head height not ground.

BTW, it's also fresh ground retrieved from weeds.  Shouldn't think it's been used for spuds for some years.

So, it has been as low as 7 or 8 at night - could that be it?  If so I'll go and fleece them up.

[DD.]

Wouldn't worry at those temps. It's only a proper frost that'll get them.

We'll have to think on!

[Salmo]

There was a frost on Saturday night that blackened the tips of potatoes here.

[lucywil]

There was a frost on Saturday night that blackened the tips of potatoes here.

didn't touch mine

[DD.]

Wouldn't dare!!

[lucywil]

Wouldn't dare!!

  you been talking to my husband?!!!

[Iain@JBA]

Sounds like frost damage to me.

[Clover]

Thanks everyone.

Since you all mentioned frost again, I've been rethinking it and you could well be right.

Maybe it's a combo of conditions; dehydration followed by frost - the yellow leaved ones aren't the ones that necessarily turned black and drooped.

Another reason I'd dismissed it was that no other potatoes on the allotments appear to be suffering, but my plot is in a dip or hollow for some reason - micro-climate maybe?

Didn't see them yesterday so God knows how bad they are now, but is there anything I can do to save them?  Should I pull off the badly affected parts or pull the whole plant before it rots, or what? (Edit: found my answer online - so no need to answer - thanks)

I can fleece for a couple of weeks in case of further damage.