Reasons why a potato plant would go flop

[Millymollymandy]

I'm baffled here. Had two 2nd early plants go all sickly and yellowing and droopy whilst the rest of them look fine. It's not blight or colorado beetle or dryness (if they are dry so are the rest).

So I dug them up to see what critters must be eating the roots but nothing! I've even got enough healthy looking spuds for the two of us for dinner tonight - obviously these 2nd earlies need several more weeks but the biggest spud was about 3 inches long and there are several 2 inch long ones and no signs of any nasties whatsoever!

So why did they go flop?

[Odsox]

Are the stems black where they come out of the soil ?
If yes, then it's black leg which is caused by diseased seed and nothing that you have done wrong.
The others should be OK if that's the case.

If not ... I haven't a clue.

[Millymollymandy]

I didn't notice but I'll go and have a look now. I thought that was a turkey disease though?

[Millymollymandy]

Nope, nothing black or untoward, perfectly healthy looking stems and roots!

Guess it'll remain one of life's little mysteries. Anyway I have some nice spuds for my dins along with about 15 peas and about 6 rather small broad beans. But I won't go hungry as most of my dins is mange tout.

[Millymollymandy]

Another one is doing it too - I wonder if it is the variety of spud because these are the freebies given out by the garden centre which are never well known (in France) varieties - wonder if they are more trial type varieties? I never see the ones they've given out free in previous years suddenly joining the ranks of the known varities at the same garden centre!

[Merry]

I was interested to read this thread because I`ve got one or two plants in each row of spuds going yellow and keeling over. No sign of disease or beasties and when I dug one up yesterday I found eight dinky little spuds - not nearly big enough but looking healthy.
Dunno what it is - none of my allotment neighbours are having the problem.

[Gem]

This may sound a bit foolish to a more seasoned potato grower but its not something simple like insufficient water?..

[Durgan]

This may sound a bit foolish to a more seasoned potato grower but its not something simple like insufficient water?..

Highly likely.

[Millymollymandy]

No, mine are always on the dry side but even when they've been really dry they've never done that. It wouldn't make sense as they are all watered the same amount. The ones on either side are green and healthy then suddenly one will go yellow and limp. The spuds are perfectly healthy underneath!

[MKG]

It sounds almost as if something has convinced those particular plants that they've reached full maturity.

Mike

[Millymollymandy]

Well it wasn't me cos the spuds whilst edible need to grow a bit bigger yet.

[Ratsny]

My husband is doing research on this at Lincoln University in NZ...
There is a new disease (going global ) that is transported by an insect called a psyllid (kind of like and aphid) that is attacking potatoes and same type plants (eg toms). It causes die back and makes the tubers inedible. If unsure, take a slice of the potato and fry it in oil - if it comes up stripey then it is likely to be this disease.
DeanO's research is exploring the use of beneficial bugs to combat the psyllid.
Because we don't want to spray we are growing lots of buckwheat and phacaelia to attract parasitic wasps and ladybirds. And by the looks of it we will never be rid of buckwheat and phacaelia!!! So far our potatoes are ok and we have lots of bees, ladybirds and little cute wasps hanging around.
Good luck with this - it's pretty gutting when your harvest goes kaput.
If anyone knows how to get the black seed covering off buckwheat without a fancy machine I'd be interested!

[Millymollymandy]

That's all we need, another pest to attack spuds and toms - as if blight and Colorado beetle weren't enough!

Thanks for the info Ratsny but mine are edible so I don't think it is that.

[Durgan]

No, mine are always on the dry side but even when they've been really dry they've never done that. It wouldn't make sense as they are all watered the same amount. The ones on either side are green and healthy then suddenly one will go yellow and limp. The spuds are perfectly healthy underneath!

Several years ago I had four very health potato plants in a small area. One day one went limp and I was astonished. Digging down into the soil I found the roots were bone dry. I tried to revive by heavy watering. The plant did not revive. The other three plants appeared healthy and normal.

This limp appearance appeared almost before my eyes, and the suddenness of the circumstance was truly astonishing. Watering heavily hilled potato plants is a problematic business, since it is highly unlikely that any moisture gets to the area of the roots where it is needed.

[Millymollymandy]

That's why I haven't earthed them up this year but planted them deep the same way as you have. It's so much easier to water and do Colorado Beetle inspection.