White potato stem - fungus?

[Cutecumber]

I am assuming I have some kind of fungus on the stems of a couple of potatoes.

It is around the soil level but is not affecting all stems in the pot - yet! It is white, powdery (similar to powdery mildew, but thicker) and when wiped you can see the stems have been eroded underneath. The stems are still strong and the fungus does not go far down below the soil level. My tubers are not nearly ready, otherwise I'd tip the whole lot out.

I've never seen this before - I've had black stem rot, but this ain't it.

It has been incredibly wet and windy for two weeks here, and I wonder if something has been rained or blown in. I have been topping up with compost, but other pots which I have also been topping up are so far unaffected.

So far, I have washed the stems, pulled off lowest leaves and given a seaweed boost.

Any ideas as to what it is, whether the tubers will be affected, and if there might be an organic solution?

Many thanks.

[Alice]

I think this problem came up last year Cutecumber. If I remember correctly the answer was really nothing to worry too much about. You could try a search on the Vine or wait and see what others say. Good luck with your potatoes. I think you've done all you can do. I do hope your potatoes will be fine.

[rustylady]

Potatoes do much better in open ground than they do in pots. I do appreciate that many people only have space for pots (live in cities, no gardens, no allotments etc), but if you're growing in pots you really do have to be careful to get the watering and humidity right, otherwise you will get all sorts of fungus/mildew problems. Are your potato pots in a greenhouse or outside, Cutecumber?

[Cutecumber]

Thanks.

My potatoes are in large pots outside. I've done them for years in this way and this is the first time I have had a problem. The weather has been "interesting" this spring.

For comparison, when I planted some in the ground, the slugs massacred the top growth. The potatoes were much bigger than I get in pots, but fewer. Oh, and I couldn't find them! lol!

I guess I'll wait and see what happens - it's not getting worse.