[Snoop]

This is my second year growing Dunluce. Last year I had an amazing crop, but not this time round. Flooding forced me to plant them this year in less than ideal conditions: very heavy, previously uncultivated but weed-covered clay soil, to which I added muck that could have done with another few months of ageing but it was all that was available. The Dunluce I've harvested so far have been small in size and very few in number, OK in flavour but a bit scabby. I could leave them longer but this is already significantly longer than I left them last year - by this time last year I was picking surprisingly sizeable pots, this year they're not even small egg size and some would barely classify as gobstoppers.

I don't mind about the scab so much (nothing a peeler can't handle and not every potato is affected) but I would like to increase the harvest of my other potato varieties. I've given all the potatoes (including the Dunluce) extra P and K as well as additional N. I've just bought some new granular fertiliser that contains N, P and K (weighted towards the K) and traces of sulphur, magnesium and boron too. But I was thinking that perhaps some calcium might help too. I have some ground hoof (it's the closest I can get to BFB),  but it sets the dogs on a digging campaign, so not a good idea I also have some calcium foliar spray that I've never used and was wondering whether this might be a goer of an idea. But there's something about using foliar sprays that leaves me a bit uncertain: do they really work, would it be good for potatoes and might it not cause fungal problems?

Does anyone have any views or other general advice?

[Markw]

Snoop this is the second year I have been using a biostimulant  leaf foliar spray, I have had no problems with it and it does improve velds, especially on the spuds, there are a few on the market at the moment, the one I use is also very good for bringing on young plants, the one I use is made from chicken manure. 

[Snoop]

Thanks, Markw. I'll get on the case later this week, after it's stopped raining (again).

[JayG]

Do you know which calcium salt your foliar spray contains Snoop?

If it's a carbonate, bicarbonate or slaked form it might not be a good idea to add it even to the leaves as any of those will raise the pH of the soil slightly when it gets washed in, which might make the scab problem worse.

This article explains some of the causes of scab, which in your case may have something to do with either a naturally high pH or possibly the not fully composted manure.

[Snoop]

Do you know which calcium salt your foliar spray contains Snoop?

Thanks for the reply, JayG. It's CaO (calcium oxide complexed with lignosulfonic acid). I bought it a couple of years ago, as I identified a calcium deficiency in my tomatoes. We had quite alcaline soil in my veg patch at that time (7-7.5, probably now remedied to an extent by lots of muck)  and I had wanted to buy agricultural gypsum but couldn't get it locally, so went with this liquid. However, I've never used it, as the following year I added wood ash (olive and almond) and have done so ever since. All the locals comment on how healthy my plants look, so wood ash it is. But I understand that ash can't be used with potatoes.

I don't know what the pH of the soil is where I'm growing them now. I imagine it's quite alkaline though. The article looks very interesting, thanks for the link.

[JayG]

Yes, wood ash is sometimes used as a substitute for lime, and contains other useful nutrients too, but as you say it's not a good idea to use it on spuds unless the soil is too acidic even for them.

Hard to imagine Spanish grown spuds having too much water  - hope they perform a bit better when it dries up a bit.