Black Spud Confusion —

Back in 2010 I posted here about the black potato "Négresse" which I grow every year. The article kicked off some speculation about naming confusion between Négresse, the very similar Congo, and a third potato, Vitelotte...

Well grown examples (if I do say so myself) of the blue-black fleshed potatoes Congo(left) and Négresse.

Having grown Congo and Négresse together for a couple of years now, I can confidently say that they are not the same variety. Appearance, eating qualities, and resistance to tuber blight are similar, but...

—Négresse has a squarer shape than Congo (most obvious on fully mature tubers).
—Négresse tuberises slightly earlier (or at least gives more crop by early July when mine were killed by blight last year).
—Their foliage is noticeably different.
—Négresse has a shorter dormancy period.

I have said previously that I suspected Negresse was truly day-length sensitive (like oca); the plants will continue to grow without naturally dying back, until the first frost. Actually I now realise that very small tubers are formed by mid summer, so the plant is not day length sensitive. But they do need a very long growing season to reach the size of those in the top photo.

Here are my lazy beds in June last year, complete with authentic blight blackened foliage...

I was expecting to find no tubers at this time of year, but I was pleasantly surprised to find small tubers had already formed.

And then there is Vitelotte. Wikipedia says this is synonymous with Négresse. So do seed merchants Thompson and Morgan who are selling them as micropropagated mini tubers this year. Others say they are clearly different, so who knows. I certainly get larger tubers than those shown on the T & M site.

Changing the subject, an annoying problem with all these black potatoes is finding the well camouflaged tubers in the soil at harvest time. Missed tubers result in persistent volunteers which can be real pests amongst a following crop. No such problem with this new (as yet unnamed) variety...

...which has spectacularly prominent fluorescent pink skin and flesh!

Sunglasses not included.

More Mashua

Last winter I wrote (here) about the Mashua variety pilifera, and mentioned collecting its true seed. For whatever reason, that seed didn't germinated, but my post did result in a generous offer from Mybighair; wildling tubers seeded from his Ken Aslet, a day-length neutral form, arrived in the mail. Back in April I got tired of waiting for Spring, so between downpours, I planted the tubers in the cold, nutrient depleted mud, then retired indoors for the rest of the year, leaving the mashua to sink or swim. Literally.

Here is the resulting crop from "Son of Ken 1" lifted yesterday:

The four plants have all demonstrated fairly early tuberisation, acceptable flavour (to me), and exhibit varying degrees of the characteristic stripes of the parent. Diversity is good.

The fact they survived this year's hellish weather and waterlogged soil is not just good, it's amazing.

Some tubers are faciated, a condition which can result in larger, albeit strangely shaped tubers, and the genetic disturbance may sometimes be passed to the next generation, so I will replant next year. I don't pretend to understand what's going on with the genetics - I simply plant, observe, and select.

I grew "Son of Ken 1, 2, 3, & 4" right next to the Pilfera, hoping to collect seed from crossing, and I did see some flowers forming in early autumn, but if they survived long enough to be pollinated before being battered to the ground by rain or hail, they were probably ripped away by the regular gales we've suffered this year. So no seed.

Anyway, Pilifera cropped well again, though several young plants vanished during the so called spring, probably raided by desperate rabbits. Here are some of the best tubers from the surviving plants:

Mashua is said to be pest-free, but there is one significant exception; the plants suffered a massive attack from cabbage white caterpillars in August.

I picked about half a bucketful by hand, but the foliage was already badly stripped. Notwithstanding this, the plants made a good recovery. Perhaps Mashua would be a useful decoy crop alongside (or amongst) brassicas.

I've also noticed that many of the harvested tubers are spoiled by these strange brown fringed splits forming round the eyes. I'm guessing this could be caused by over-rapid swelling from high soil moisture levels i.e. growing in mud.

Possibly the staining is the concentration of chemical defences migrating to the vulnerable exposed surfaces.

Another observation is that the underground tubers are ignored, or perhaps more accurately avoided, by voles. There are voles aplenty here, and the oca are taking a bashing, but not a nibble on the Mashua. Maybe the voles are spoiled for choice with all the oca about, or perhaps they agree with a proportion folk who find the taste of mashua to be repulsive. I am not one of them, and when other crops fail, it seems there is mashua to eat.

Love it or loathe it, if you have tasted mashua, you can contribute to an edibility survey over at Radix.

Damn climate change! Next year: build windbreaks, dig drains, collect mashua seed. Wish I hadn't burnt those hydrocarbons now!

Breaking New Ground for Tuber Planting — The Celtic 'Lazy Bed' Adapted

Since the move, I have access to ample land, but none of it has seen recent cultivation. In fact the soil is compacted, stoney, and seems to contain very little organic matter below the top four inches. It would be heavy work for a spade, and the area too great.  Other methods are urgently needed if I'm to catch the planting season.

The 'lazy bed' method was used historically in Ireland and the West Highlands to grow potatoes on unpromising land. Its advantages include minimal disturbance to soil fauna, conservation of soil humus, and most importantly, economy of effort.

I started by mowing the area to be used for the bed. This is not absolutely essential, but the resulting short vegetation will be more reliably killed off by the lazy bed technique. My Simon Fairlie Austrian scythe did the job in a couple of minutes...

Next, mark out the bed with lines. I'm opting for three foot wide.
Rake the grass cuttings onto the bed area, and simply drop the seed tubers in place...

Add any available organic matter (traditionally seaweed, but in this case rotted hay) evenly over the bed area...

Now, make a vertical cut in the turf one foot out from the bed-edge. I used a wooden batten as a straight-edge.

Then the one-foot strip is is turned over onto the bed to bury the tubers. This involves a lot of bending if you use a spade, but is very quick and painless with a digging hoe (Azada)...

Two chops with a digging hoe to undercut the turf...

... and follow through with a deft upward hoik...

... assisting the turf into place with the boot.

It's important to maintain a hinge of turf at the fold point, otherwise weeds will not be smothered.

Repeat the turf-folding on the other side of the bed...

...and finally, add loose soil from the bottom of the trenches to the centre of the bed. A long-handled Irish shovel makes easy work of this...

Whew. All done in two hours.

The second bed is quicker since one edge is already cut.

Some weeds will inevitably grow through, so this technique is most suited  to crops with vigorous foliage giving good smother characteristics — main-crop potatoes, oca, yacon ... I'll see what else I can get away with.  Anything to avoid digging. Any surviving perennial weeds will be forked out at harvest time, leaving clear ground for overwinter crops.

There's more on the use of authentic lazy beds (including demonstrating their advantages in poorly drained soil) over at Connemara croft.

Update (Above) Oca plants in early summer. Extra mowings have been added to the surface of the beds to suppress weeds until the crop canopy closes over.

By late June, blight has finished the potatoes, so I'm lifting some. Turf incorporated in the bed has not fully decayed yet, making it difficult to dig, or prepare for a following crop.

The Oca crop in the shot is now giving full weed suppression...

...and once winter frost has killed back the oca foliage, the few remaining perennial weeds are visible.

When the crops are lifted in early January, the soil is clean and friable with just a few weed roots to pick out, and I'm glad to say, lots of earthworms. 

A quick rake over and this will be ready for planting garlic or early spring crops.

Really, this ground should be double dug at some point, but the lazybed method is very effective as an initial sod breaking technique to get the space productive with a minimum amount of labour.