It is the same every single year. I dig up a handsome harvest of maincrop spuds, and nearly all of them look like they’ve developed a nasty case of acne.
I dream of smooth-skinned, downy-cheeked potatoes: I fantasise about peachy skins free of crater-like blemishes and crusty patches. But I have to make do with these.
It’s not the end of the world, I know. You can peel the blighters, and they taste the same: this is a disease that’s only skin-deep.
But I like my spuds unpeeled: not only do you keep all those nutrients that would otherwise end up in the compost bin, and you also save yourself a shedload of work.
However, scab is a potato disease I have had to learn to live with. It’s a bacterial, or sometimes fungal infection which lives in the soil and gets under the skins of your developing spuds during the summer, causing them to break out in cracks and pustules. It makes you wish you could get in there and rub some Clearasil on (not that you’d want to eat them afterwards, I suppose).
The trouble is that scab is mainly caused by dry conditions as the tubers are forming: and since they’re generally forming in summer, that’s most years, then. This year my potato crop has been particularly water-starved after that six weeks or so we had completely without rain. But in truth, no year when you’re gardening in the south-east is exactly waterlogged – even the gloomy summers of ’07, ’08 and, largely, ’09 (remember them?) were mostly cloudy and dull in my corner of the country rather than actually soggy.
Potatoes need epic amounts of water in the soil if they’re to do well. The RHS recommends an eye-watering 20 litres per square yard – that’s about 15 trips with the watering can for each of my 3.5 sq yd veg beds. And I’ve had five beds of potatoes in this year. To be honest, if I’d tried that I’d have been doing nothing but watering all summer long.
There’s always drip watering – these days there are dripper systems you can attach to a water butt, so if you chose one of the bigger sizes - 350 litres looks pretty good to me – you’d have a few days at least between refills. And plenty of organic matter such as well-rotted farmyard manure, dug into the soil before planting, not only feeds the spuds but also holds water into the soil, so what you put there, stays there for your potatoes to benefit.
But in fact what most of us end up doing is just putting up with a bit of scab. You can minimise the damage; alkaline soils make potatoes very prone to scab, so if you’ve limed your brassicas to avoid clubroot, don’t grow potatoes there the following year.
Of course, you can always move house. It’s a bit of a drastic solution but it does neatly sidestep a few problems. In my case, I’ve swapped the drought-stricken south-east for the notoriously damp south-west. However, it’s not always that simple, and though I may have acquired soil which promises to be a watering-can free zone, I have somehow overlooked the fact that it happens to be in a former chalk quarry. Which means alkaline soil. Which means…. scab.
You see? There really is no getting away from it. However I do have one last weapon in my armoury: there are potato varieties which are known for their resistance. They include some of my all-time favourites. ‘Arran Pilot’, ‘King Edward’ (not normally known for its disease resistance) and ‘Pentland Javelin’ are all on the list. If you want to find more I suggest you visit the rather wonderful British Potato Varieties Database, which lets you search for varieties by size, colour, and disease resistance. I found the variety in the picture, ‘Blue Danube’, rates a rather miserable 3/9 for scab resistance: that explains a lot. It also explains why, even though it’s wonderfully blight resistant – best of the lot this year – it’s not making it back onto my list of spuds I want to grow again. The search for good skin continues.
