Potatoes Update!

[robototitico]

Dear friends,

Having posted here some months ago seeking advice re growing potatoes in winter, I now have 6 large tubs, each containing 3 plants!! (I planted them in the beginning of september). They are mostly tall, healthy, and green.

One of them however seems to have developed a problem, on which I would like your advice.




If the above picture isnt appearing, click here: http://pg.photos.yahoo.com/ph/ptwrenn/detail?.dir=4833re2&.dnm=f587re2.jpg&.src=ph

[robototitico]

[manicscousers]

are they scale insects ?  don't know how to get rid, not had bad problems with them, maybe someone else will have more ideas  :D

[Merry Tiller]

One of them however seems to have developed a problem, on which I would like your advice.

Er, yes?

[robototitico]

As you can see in the picture, there are brown spots on the leaves of one of the plants.

[Merry Tiller]

Sorry, I'm not seeing a picture ???

[triffid]

We can't see the picture!

[robototitico]

for real? I put the image into my first post. Well I can see it anyway.

Here is a direct link http://pg.photos.yahoo.com/ph/ptwrenn/detail?.dir=4833re2&.dnm=f587re2.jpg&.src=ph

[triffid]

Ok...

Looks suspiciously like the beginnings of blight to me.

If it's scale insect (see manicscouser's post, above), you'll be able to pick/push them off with a fingernail -- they're a bit like tiny limpets.

But that picture looks more like blotches on the leaf itself. It wouldn't be surprising, given the amount of wet weather we've had.

See what Merry Tiller has to say...

[robototitico]

Thanks for your reply.

Is it contagious? Do I need to quarantine it. If it is blight what do I do?

[triffid]

If it's blight then yes, it is contagious (it was the reason for the Irish potato famine.)  :(
It's a fungal problem: it starts on the leaves, then rain/watering washes it down on to the soil where it attacks the spuds themselves, causing them to rot. 

Ok, that's the bad news.

Hopefully, your spuds have already formed (this depends on the variety you've planted: let us know that and we'll be a little wiser.)

If it's just a few leaves, start by picking them off (plus any that have fallen on to the soil). If it carries on getting worse, or if it's already all over the leaves, you'll need to cut all the haulms (stalks, leaves & all) down to the ground.

(I wouldn't compost the infected haulms, unless you have a very hot compost heap.)

Then, leave the spuds in the ground for at least three weeks so you don't infect them with spores when you harvest them.

[Merry Tiller]

Could be blight, hard to say. Are there similar blotches on the stems?

[philcooper]

The pictures are not very clear.

If it is scale insects they are raised and visble on one side of leaf only

If the drak spots go all the way through the leaf then it could be early blight - late blight produces yellowy brown markings

If it's just a few leaves, start by picking them off (plus any that have fallen on to the soil). If it carries on getting worse, or if it's already all over the leaves, you'll need to cut all the haulms (stalks, leaves & all) down to the ground.

(I wouldn't compost the infected haulms, unless you have a very hot compost heap.)

Then, leave the spuds in the ground for at least three weeks so you don't infect them with spores when you harvest them.

Early blight isn't much of a problem - I would leave them alone. If the blotches do get yellow surrounds then follow the above advice. But the need to leave the ground undisturbed for 3 weeks is to allow the blight spores to die. If not they may get on the tubers and cause tuber blight which will rot the tubers, if you try saving them. As you want new spuds then if you have no problems just lift and eat (if there are any tubers yet)

Phil

[robototitico]

Hopefully, your spuds have already formed (this depends on the variety you've planted: let us know that and we'll be a little wiser.)

They are Carlingford. The blotches are only on the leaves.

[triffid]

There you are, robo, lovely clear advice from phil (and a very sensible point about you wanting to munch your Carlingfords sooner rather than later!)

Enjoy 'em when you do!

Probably best to keep the blotchy bits out of your compost heap, though, just to be safe  :)

[robototitico]

Thank You All!!