Oca Harvest? Wait for It, Wait for It...

These are my main 'eating crop' of Oca...

It's more than two weeks since frost killed off the top growth, and received wisdom says now is the best time to harvest for maximum yield.
They certainly look as if they've completely snuffed it — until, that is, the top layer of dead foliage is pulled back...

The stems underneath are still green and succulent.
And below ground, roots and subterranean stems are also alive and well, continuing to build tubers...

An interesting approach would be to try to enhance this self-protecting effect by using closer plant spacing. The resulting denser foliage might provide sacrificial protection against significant frost in much the same way as a covering of horticultural fleece.
Using raised beds, earthing up, and planting under suitable taller crops are also cultural methods that may give partial frost protection.

It's a gamble to wait too long, as I found to my cost in 2009, but the weather has been mild and as a result vermin have not been digging up the tubers much. The ten-day forecast shows no imminent frost that would spoil tubers close to the surface, so on balance, I think it's worth waiting to give those tubers the maximum time to bulk up.

Oca Breeder-Packs Up for Grabs!

I'd been planning to be able to send out small packs of true Oca seed (TOS) to any interested growers, but it turns out that TOS was the preferred high-protein snack of a particular ex-mouse, and my bountiful stock has been decimated (in the modern, not the relatively trivial Roman army sense).

So I'm doing the next best thing by offering packs of tubers suitable for breeding.

These consist of a range of tuber varieties that I can guarantee from previous experience contain the necessary potential flower power and variance to allow successful pollination. You will notice my careful use of the word 'potential'; any grower will still have to provide suitable conditions, have a climate that favours flowering, spend time and care pollinating, and additionally have fair luck to obtain simultaneous flowering of dissimilar flower forms. There are more full details of the process here.

I'm offering these free (postage costs appreciated), or for swaps. Stake your claim as a comment below (first come first served), and  send me an email (obtainable from my Blogger profile) with your postal details.

By the way, if you want tubers just to grow a crop, these are not necessarily the most productive varieties, and you will do better by obtaining tried-and-tested stock from Real Seeds.

Update 13/1/12. I've just sent out the packs. Here are the tubers sorted and ready to bag...

Everybody gets about nineteen varieties, one tuber of each. I've selected them from productive healthy plants, and have chosen the cleanest, best-shaped, unbranched tubers. They are not necessarily the largest, but there are no tiddlers either. Mid styled flowerers are in the majority, but there are definitely some of the other flower types in there.
Some of you are getting other seeds etc thrown in by arrangement. They are labeled separately.

The offer is now closed. Good luck for this year Oca breeders!

Assessing Some New Oca Varieties

Back in spring Frank Van Keirsbilck sent me a package of tubers to supplement my usual planting. These were grown from true seed, and thus relatively untested as productive varieties. Last week the weather was still holding frost-free and perfect for continued tuberisation, but I decided that lifting them early would be a good idea. They are going to be used solely for propagation material, so hanging on for maximum tuber size would be no advantage. In fact, lifting early would be better for identifying any less day-length-sensitive individuals. Also I was impatient.

This is "NZ003", his reference variety, which he also sent me, already showing a good yield...

The plants have been rigorously neglected all season as part of their selection process. They were planted in newly cleared ground, then left unweeded, unwatered and unattended.
By the way, if anyone doubts Oca's ability to outcompete weeds, have a look at this...

... Folding back the mass of foliage reveals completely clean soil.

Anyway, as would be expected there was a lot of variation in tuber appearance...

and also in productivity. A couple of plants expired during the growing season, some produced feeble crops, while others challenged the reference variety on productivity.  I've listed all the varieties, with their crop weight on this Google doc if you want to have a look at the details.

Of note would be 026 which produced this fasciated tuber...

...and 023, very productive, and many of whos tubers are characteristically elongated and possibly fasciated. This seems very interesting, and could be a route to increased tuber size.

014 and 008 yielded beautiful clean tubers...

This last one is not one of Frank's. It's grown from slips taken from the pink striped tuber that I got from Joel Carbonnel. Strangely the tubers are neither striped nor pink, but show varied colouration, and tiny flecks of purple at the ends of some eyes. It seems as if there is some instability going on, so this could be  one for development. In any case it's a good cropper.

Meanwhile my main bed of 'eating' varieties was frosted back the other night, so they'll be ready to lift in time for Christmas.

Grand Theft Oca !

Yesterday this tray contained about 700 true Oca seeds, ...

... the culmination of a season's painstaking hand-pollination and collection. Today it contains two seeds and a few shriveled seed capsules.
They were undergoing their final drying, sitting 'safely' on a table in my work room.  I was planning to offer most of them for distribution or swapping.
Given that there were no signs of breaking and entry, and that no-one in the house has a history of sleepwalking, I was left with the possibility of...  ...Hmmm, there had been rumours of a mouse in the house for a while now.  It didn't seem very likely that it could have climbed the stairs, then the smooth painted steel table, ignored rows of farinaceous delicacies such as dried heritage peas and assorted tubers without giving them a nibble, then polishing off all those seeds in one sitting.
But there was no other possibility,  so it's a job for Little Nipper and a tahini-smeared raisin. The penalty for this crime is death!

Bingo. One rather well-fed mouse! I did seriously consider an autopsy to recover the stolen goods, but I think they would already be mouse droppings by now.

He did leave two seeds, and there are a few more from a final batch of pods yet to ripen, so I'm not quite wiped out, but this is still a massively disappointing setback,

...and another lesson learned.

November is Tuber Time

Most conventional vegetable crops are on the wane by now, but the short days mean only one thing for Oca...

...make tubers, and make 'em fast! These stem-borne Oca tubers are getting noticeably bigger every day, and I've no doubt that those underground are similarly ascendant.  In fact, in places I can see the soil surface starting to heave upwards from the pressure of the swelling crop.

A hands-and-knees survey of the plot discovers plenty more underground action. This is the Ulluco doing its best to tuberise...

...and doing better than last year, when they were already frosted by now.

Chinese artichokes tubers are also bulking up. These are from the plants used as ground cover under climbing beans in the 'root crops as ground cover trial'.

And scraping around the base of a Yacon in the 'Not the Three Sisters' bed reveals sizable storage tubers.

All this bodes well for bumper crops. But of course, a frost could easily put a damper on that.

Unfortunately someone else has noticed all this underground fodder. This is a large excavation on one side of the 'All-Tuber Polyculture Mound'...

Oca, Chi-chokes, and bits of Yacon are scattered around. Rats could be the culprits, although a lot of the uncovered tubers have not been eaten. Then again maybe it's a fox. Anyway, the damage has put a halt to a lot of the plants in the mound.

Grrrrr!

Saving True Oca Seed — It's in the Bag!

My previous attempts at collecting Oca seed have been frustrated by circumstances, but I've finally made the vital step in oca one-upmanship. And here's the proof...

... several tiny seeds safely retained in their capture-bag, along with their spent seed pods. So why it it so tricky?

Well, firstly Oca is an outbreeder; you will need to have multiple varieties (the more the better) for a good chance of compatible flower-types occurring simultaneously (flowering is sporadic). Grow them mixed closely together to improve chances of natural pollination.

Wait for (or perhaps try to induce) flowering. This can happen anytime during the growing season, but seems to be linked to available moisture or (my theory) high air humidity, as I've noticed that flowering reliably occurs whenever there is dew in the mornings. It would be interesting to confirm this using a misting system, but anyway, flowering seems far more common in wetter parts of the world, and definitely does not happen during hot dry weather.

Next, you need to be able to identify the three flower types, and understand the legitimate pollination combinations. There is a good explanation of this from Rhizowen, but here it is in very simple terms.
It's all about the pointy bits in the middle of the flower (I did say it would be simple!).

In this Oca flower, the longest pointy bits are pale yellow, while the shorter ones are dark yellow...

...so this is 'long-styled'. The pale yellow parts are female, while the darker yellow are male, producing pollen.

So what would you call this one where the pale yellow parts are shorter than the others?

...yup, short-styled.

And to make the full set, here is the mid-styled model...

Now comes the tricky bit. Flowers of the same type cannot pollinate each other, and even if you have two different types of flower, the pollen must come from the specific length of male pointy bit that matches the length of the female pointy bit being pollinated. Phew, that's the end of the technical bit.

Actually it's not strictly necessary to know all that, unless you plan to do the pollination manually. If you have bees, hoverflies, or other natural pollinators, you can just sit back and wait for the next stage. However, I have obtained higher levels of success from manual pollination (5 to 7 seeds from each flower compared with 1 to 3 when leaving it to nature).

If you take the route of manual pollination, you will need to attend to your plants during the early afternoon when the flowers are most likely to be open.

This year I have marked all of the manually pollinated flowers with brightly coloured electrical tape so that they don't get lost in the still-expanding mass of foliage.
After a week or two, it's possible to differentiate between fertilised and unfertilised pods. The photo below shows one of each; the top one is swollen, and looks like it has a full compliment of seed inside. The lower one is limp, and will soon drop from the plant, confirming that it has not been fertilised.

At this stage it's okay to leave fertile pods, safely highlighted with coloured tape, on the plant to mature. But this is not the time to go on holiday to Marbella for a fortnight. It's necessary to check every couple of days for a change in appearance in the pods; they take on a more muscular appearance, sometimes puckering up their nose ready to explosively discharge their seed. This one is ready to pop at any time...

At this point I add polythene catch bags...

...and with luck, after a day or two the pods will have blown apart, shooting their tiny brown seeds into the corners of the bags...

I'm getting a few more every day, so if the weather holds I should be well provided with seed for a mass sowing and selection next year.

Out of interest, not all Oca flowers conform to one of the three regulation patterns; here's a double flower that's never going to get pollinated naturally...

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Wildlife in the Oca, Friend or Foe?

I was initially alarmed by this chap...

...(and several of his mates) browsing amongst my Oca. I watched for a few minutes, and noted that they left the Oca plants untouched, but laid waste to surrounding weeds - a situation that suited me fine. Obviously they qualified as good-guys, and there would be no need for a messy manual squashing session.
It seems it's the caterpillar of the Cinnabar moth. Some research revealed that they are used as a biological control of their favorite food plants, ragwort and groundsel. Apparently after consuming all available ragwort and groundsel in the area, they may become cannibalistic. I do appreciate workmen that tidy up afterwards!

With some Oca flowering, I've been scrutinising stylar arrangements...

... and have noticed a lot of these tiny thrips or thunderbugs in the flowers. They suck sap from plant cells, and are considered a pest. It's possible that they could spread viruses, but on the other hand they may provide some pollination even though they seem disinclined to fly much between flowers. On balance I prefer to leave them be.

These hoverflies are much more energetic pollen stirrers ...

... and given the compatible flower types available at the moment, I'd better start keeping my eyes peeled for fertile seed pods.

Surely this will be the year!

Main Oca Bed 2011 — If It Ain't Broke...

Last year's growing arrangement of Oca with cordon tomatoes was hard to fault, so I've just tweaked it slightly to optimise spacing and make it easier to manage this time round. Oh, and it's beetroot instead of lettuce for the quick-growing edge crop.

Here is Oca 'Dark pink', not yet at the sprawling stage, growing strongly between tomato 'OSU Blue', despite being subject to a medley of drought, high wind, downpours and hailstorms since planting out.

26/6/11

Observant readers might notice that there is incomplete fruit set on the tomato. I'm pretty sure this is due to the very dry conditions earlier in the season rather than any affect from the oca foliage covering the lower trusses.

The bed's timetable in detail:-

13th April. Cleared the preceding green manure crop (grazing rye). Tops hoed off with an azada, and removed, roots left in situ. Not dug.

14th April. Beetroot (plugs, sown 15th March) were planted out.
The tiny plants are just visible in rows 9" from the bed edge (centre foreground bed)...

I could have planted out the Oca at the same time, but last year they got a bit of frost damage around now, so no need to rush things as they are happily growing away in Root trainers at this point.

9th May. Oca and tomatoes finally get planted out. The Root trainer method seems like a success, and I'm sure this will give them a better start than using pots.

Tomatoes planted, Oca laid ready to plant, beetroot doing well...

That's Cheltenham Greentop on the left, and 'White' on the right.

The tomato supports are on 16" spacing, with 24" between the staggered rows. Incidentally this assumes using the UK conventional cordon growing method (side-shooting, and deleafing lower part of stem). If you use the American cage method I'd go for much wider spacing.

5th June. Full ground cover from the  Oca between the tomatoes, and beet down the edges (beetroot now being harvested).

10th June. Tomatoes are starting to crop. (Below) This is Katja, a Siberian variety, surprisingly the first to ripen. Thanks to Søren of Toad's Garden for the seed.

31st June. Oca stems over-reach themselves and collapse down at this time of year. This, along with deleafing the lower part of the tomato cordons improves ventilation and light access. The dappled shade from the tomatoes is enjoyed by the Oca, reducing stress in hot weather.

8th August. Tomatoes in full production.

1st October. Tomatoes on the wane, Oca ascendance.

4th December, tomatoes removed after the first light frost.

Tubers are swelling!

Harvest still to come!

Not the Three Sisters...

... not the traditional corn/climbing beans/squash polyculture, but a wilder and woolier version with slightly more obstreperous contenders. The Three Hooligans might be a more accurate name for what I have in mind.

Infant hooligans on planting out day (25th May)

'Hooligan 1' is Yacon,  Fiorella,  a Czech-bred quick maturing variety which I grew last year. I can confirm that it does indeed get a move on, and makes tubers long before standard Yacon. Each plant is liable to reach 8ft high by 9ft wide by the end of the season, and produce 10 to 15 pounds of edible tubers.

'Hooligan 2' is the Hog Peanut or Talet (Amphicarpaea bracteata). I don't have any previous experience of growing this, but it's reputation as a rampant reprobate proceeds it. I'm looking forward to trying the beans which form below ground. Thanks to Rhizowen for the seed, who was also thoughtful enough to provide the required specific inoculant to permit nitrogen fixing on the plant's roots.

'Hooligan 3' is admittedly a corn, as in The Three Sisters system, but this is Hopi Blue — a robust and highly variable variety, displaying diverse foliage colour, number of tillers, and ultimate height. It's usually described as growing to about 2 m but I think that must be in its arid homeland, as I have experience of it growing to more like 3m. Almost certainly there are different strains, which also might explain this difference.

But for a successful polyculture, it's as much about how you plant as what you plant. Here's a view showing the planting layout...

That's a 5 ft wide bed. Hopi Blue are more widely spaced than usual to admit light to the Yacon which are planted on the centre of the bed at 4 ft spacing. Hog peanuts are between the Yacon, and should climb to the light. You'll also notice a couple of rows of onions in there. They were planted back in March and could be a mistake, but they were a bargain and you never know, if they get a move on they could form an extra output.

A couple of weeks later the plants have settled in...

9/6/11

... and are still well-behaved, but for how long?

10/7/11

27/9/11 Corn ripening. Flowers on the yacon are a sure sign that tubers are forming below ground. And...

... the hog peanuts are producing their tiny delicate flowers.


16/10/11. The corn is harvested...

...and the corn plants removed. The yacon are about 8ft high and steadily flowering.

More updates later.