potato question: leaves turning yellow

Hi all,

this is the first year I have potatoes planted (in pots), and they were doing quite oke (except for the enormous number of snails that are eating the leaves). The last few days however, a few of the plants is doing less good; leaves are turning yellow (and than brown, and...)
Because we're having higher temps lately, combined with rainshowers, I looked up pictures of potato disease (phytophtora), but it does not look like that (phew! ).
The soil isn't particularly dry or wet, so that should not be the problem either.
So I'm guessing it must be caused by a lack of something in the soil they're in. Do you think it would help to just ad some compost? Or should I give something specific? I remember having read somewhere that potatoes need potassium, but I'm not sure.
Other plants (same variety, same soil, just a tiny different location in the garden) are still doing ok... so maybe it's not the soil after all...

Anyway, I could use some input here! Help!
These are still healthy:

And this one is not:

Interesting. I had 3 plants in the same MM soil - 1 per s/f. All started out healthy. The one on the left is super healthy, the middle one is yellowy looking and dieing back, and the other one was so far gone I already pulled it out - and got a few potatoes too. The taters were healthy.

I did not know if I had mounded the dirt too high or what. The one of the left was always taller than the others.

I will be interested to see if anyone has any answers to this.

You can see them here - left, middle and right:

While I'm no potato expert, my experience so far is that potatoes are about ready when the plant turns yellow and starts to die back.

I'm no expert, either, but I know that potatoes are heavy feeders. You might add some quick-fertilizer such as fish emulsion and see if the color perks up, and if so then add some more compost. But it would seem if that were the problem, then all of your potatoes would be having problems unless you didn't blend the compost well throughout your mix.

Did you plant certified seed potatoes? Potatoes from the grocery store can carry diseases.

Have they bloomed yet? When potatoes bloom they are making tubers. If yours have already bloomed, then as Donna said it could be they are dying naturally and it's nearly time to harvest. Mine don't usually look like yours, though, when they are naturally dying before harvest. Mine start having gradual color changes through all the leaves, not just leaves at the bottom turning all yellow.

I would immediately isolate this plant from your others in case it is a blight of some sort.

Thanks for the answers; no, they haven't bloomed yet, our season is just starting here. I was hoping they would, though
they are certified seed potatoes, from a very very early variety (harvestable after 90 days, it says...)
I'm gonna try some extra compost, I figure that won't hurt anyway.

I can personally attest to the fact that without blooming and with the leaves dying, there can be tubers. I pulled out the smallest, sickliest plant 2 months after planting. Never had flowers and just died back. I got a few small potatoes from that one - very good too. So no matter what - it may not be a total loss.

And these were not seed potatoes, just potatoes from the pantry

Nice to know that, if the extra compost doesn't work, I may still have some potatoes...
I'll keep you posted!

Ok, an update on my yellow potatoes:

Alle the pots were given some extra compost, since that wouldn't hurt them anyway.
I removed most of the sorry looking leaves, but not all because some plants would not have any left if I did. I mean, they do need the leaves to survive.

I moved a few pots to another location in the garden, because the pots that were standing there were still doing fine. The moved ones did get by a little, although they're still a bit sad looking after having lost a lot of leaves and some stalks.

The ones that I left in the same location did get a bit better, but we've had a lot of rain and hard winds lately, so they're still not looking great. So today I sacrificed one of the pots, to see what was happening below the soil.

It turns out the soil in the bottom of the pots was too wet after all. Although the top half was fairly loose and dry, in the bottom is was really wet. So I harvested the potatoes from that pot, about 8 oz of cute small potatoes, coming from 2 seedpotatoes. Not much, but there were about 12 tiny ones too, still far too small to use, so I guess I'll be getting more from the other pots later.

And ofcourse I'm gonna taste the ones I got from this pot tonight... looking forward to that!

I noticed today that my potatoes have begun to bloom....what say you, SFGers, do I pinch the blooms, or let it go? The plants are about 80cm/2-1/2 feet tall, and extremely healthy-looking, with thick stems and lots of leaves.

Delay things, or let nature run its course early?

Lafee,
I remembered reading about taking the buds off to cause them to grow more tubers. I found the thread and am posting it here Potato Thread
I havent seen any blooms on my potatoes but I do plan on taking the blossoms off. I figure I have to get more than I got last year and my row garden. Im ok with experimenting. I might leave one plant to bloom and others nip.
Hope this helps
Ha-v-v

Some people say removing the blooms diverts more energy into producing tubers. I've never bothered with it and I raise plenty of potatoes. I can't imagine the flowers would divert that much energy unless they form the "tomtatoe" fruits that look like small green tomatoes - Yukon Gold do that fairly often and I had some do that this year. I remove those so no one eats them by mistake - they are poisonous.

Mine are over two feet tall and trying to bloom (I *want* another riser!!) but I have been nipping off the buds. No idea if it makes a difference.

Ha-v-v, I hope you leave one as an experiment. I'd like to know if it really makes a difference. (I'd try it on my own but my husband dug them all on Saturday. We don't normally harvest this early but the heat index here hit 107 and that pretty much finished the plants.)

Our harvest from our row garden wasn't as much as we'd hoped - a five-gallon bucket full plus about a fourth of another one - but we had such extensive vole damage from earlier in the spring we were just happy that they left us any at all.

We are going to try growing a fall crop.

Ander I will do that, They have no blossoms at the moment. I love experimenting I potatoes in a 10 inch box and in a faux sfg bed (no sides built up).
Im so excited with all the planting and waiting to harvest for all of us
Ha-v-v

Well, we built another riser with 2x12 lumber. Now just have to wait for a late evening after the bees have gone home to try to slip it over the plants without crushing anything. Think I may try to sort of wrap the plants gently in a tarp to hold the stems together and away from the edges until we get it into place.

Megan wrote:Well, we built another riser with 2x12 lumber. Now just have to wait for a late evening after the bees have gone home to try to slip it over the plants without crushing anything. Think I may try to sort of wrap the plants gently in a tarp to hold the stems together and away from the edges until we get it into place.

I am so jealous. I need one more riser too, but it will have to wait for the next go round. I have an idea for easy store risers too, made of PVC and weed cloth. Have to play with it for awhile and see if it is workable.

Chopper wrote:

Megan wrote:Well, we built another riser with 2x12 lumber. Now just have to wait for a late evening after the bees have gone home to try to slip it over the plants without crushing anything. Think I may try to sort of wrap the plants gently in a tarp to hold the stems together and away from the edges until we get it into place.

I am so jealous. I need one more riser too, but it will have to wait for the next go round. I have an idea for easy store risers too, made of PVC and weed cloth. Have to play with it for awhile and see if it is workable.

We just finished installing it (at about 10 pm!) Filling it with straw/etc will have to wait for tomorrow, though. The trick with the plastic worked well. (I would have taken pictures, but much too dark!)