Potatoes in chip at Dawson Creek

This is my second year working with potatoes in wood chips.  Last year, I had imperfectly controlled fecue sod which I put about 3 inches of chips on top of, then a 1 inch layer of soil, laid the potatoes on the soil, and then covered with 5 or so inches of wood chips.  No hilling was done.  The yield I got was about 1:1, and the potatoes tended to be small.  I did very little watering.

Last year, I also had about 800 square feet of fescue sitting underneath black plastic.  It stayed that way until this spring.  I placed about 1 inch of soil on the suppressed (killed?) fescue, laid the potatoes on top, and then added about 2 inches of wood chips.  Other spots gardened last year, got variations on this recipe so that I have about 1200 square feet in potatoes and used 140 pounds of seed potatoes.

Early on, I caught unconvered potatoes probably from the work of bambi.  But, we also get a lot of wind and some strong rains, which probably uncovered their share of potatoes as well.  So, I kept covering them.  Not all locations where a potato was laid on soil, have now shown a plant starting at the surface of the wood chips in the vicinity of that potato on the soil.  Some locations now have plants about 12 inch tall (we have had almost 2 weeks of on and off rain showers).

A couple of days ago I made a half hearted attempt to start hilling with a small pile of wood chips near this 800 square foot strip.  It was apparent to me, this pile of wood chips was nowhere near enough.  Today, I filled the box (just to top of box, not overfull) of a Toyota Tundra with wood chips, and I have done maybe 5-6 feet at the one end.  I am using a trenching shovel to direct the wood chips between potato plants.  As some of the potato plants are just starting to break through, I ambeing careful in not burying those ones.  I suspect it could take 4 more loads of wood chips to hill all of this strip.  The taller plants are at the 2 ends, and there is about 20 feet near the centre that is abotu 2 weeks behind (because it was too wet to plant).

Hi Gordon,

I think with a bit of tweeking, your system could be very productive, not just in growing potatoes, but also prepairing ground for other crops.

Do you have acces to: free horse manure, free cardboard, old hay or straw, more wood chips, and availability to purchase or make mushroom spawn?

If you could lay down up to a 4 inch layer of composted horse manure, putting the potatoes nestled down into that maunure, then lay cardboard strips on all the pathways, leaving only about a six inch strip open where the potatoes are planted; then put your mushroom spawn on the wet cardboard after wetting it down; next, layer your hay and straw over everything, between 2 and 4 inches if possible; then up to 8 inches of wood chips.

This will provide ample nutrients to grow your potatoes, while holding in moistre, and growing your biological diversity. It will also provide and extra crop of mushrooms in the fall and or following spring, that will keep producing if you add more woodchip mulch as needed. The mushrooms quickly make mushroom compost, building your organic matter and humus, while feeding the soil biology. After the spring planted potatoes are done, a short season crop of squash or cucumbers could potentially be grown if time allows.

They type of potato variety you choose will depend on how it grows, so make sure you choose a determinant, fast maturing variety. The thick mulch layer allows for much early planting, letting the potatoes emerge as things warm up. The determinate potato variety will help with the short norther season, and to reduce the need for hilling. Fingerling and smaller varieties of fast maturing potatoes planted early, could help make double cropping more feasible with other short season plants like some varieties of cucumber or zucchini. Not sure how long your season is, but with the right varieties, and container planting starts for your second crop, a second crop may be possible with a little leg work figuring things out.

If your woodchips are mostly hardwood, King Stropheria spawn will be the best options for a mushroom crop, and if its most coniferous softwood chips, Blewit spawn is the best option.

I realize the initial set up is 4 times more work, but it will save you from doing that work again for about three years, while in that time frame, you grow three times more food that could be very aboundant in low maintenance production.

Food for thought!

Hi R.Steele.

I am hoping this is a method to deal with my 42 or 43 year old fescue pasture (well, there is white, red and alsike clover and alfalfa in there too, but it is mostly fescue - ignoring "weeds" of which there are many kinds).  I may need other methods as well.  I also have 7 squash plots in the pasture this year.  I scalped off about 2x2 foot chunks of "sod", added some soil on top of the clay soil, and then planted two squash seeds at each corner of the "open area" in that inch or so of soil.  One of the 7 squash plots, either had no germination or if there was germination the plant died from lack of water (no water over 3 days).  So, I added 8 new squash seeds there, but there probably isn't time for that to mature.  It just happened to be the location that tends to be the wettest of the 7.  Later on, I placed a single Cornus Kousa (Satomi) seed in the centre of each plot, which may germinate next spring.  If it does, I will have to scalp other places for squash to start.  

As of last fall, I had 41 loads of wood chips on my property.  I am working away at the oldest drop of wood chips I have, which is now 2 years old.  I have asked the various people chipping wood, if they would drop again here this year.  I should soon have a 52 hp tractor with FEL, which will speed up chip work.  I have no animals on the property (my fence isn't fit for cows, let alone other things).  I do have a neighbour who has a lot of cows and horses; but I haven't talked to him about things like manure.  Dawson Creek has a few stores that sell things in big cardboard boxes, I haven't asked about getting cardboard yet.  On the way to town, there are a dozen or so BIG square bales of what I assume is pea straw, just piled haphazardly.  They might be available.  There are probably people with old hay or straw.  I have no idea if anybody in the area has mushroom spawn.

The wood chips were mostly derived from the local power utility doing maintenance on power line right of way.  So, they are mostly aspen, willow and poplar; with  some other stuff in it.  There might be some conifer wood in there.  I really don't call aspen or poplar a hardwood; but there might be some birch in there.  I doubt there is anything like oak in it, and I don't know if anyone other than me has planted walnut up here.

Your lasagne seems to have more in common with what I did last year.  Well, except that my soil is about 50% peat moss, 25% commercial "soil" and 25% composted sheep manure.  My soil was 1 inch thick, and you are talking significantly more than that.

None of the potatoes were cut to make more seed.  They were all entire potatoes set on the soil.

What I am hoping for, is that over 2 or 3 years, the potato roots may break up the fescue sod, so that there is "communication" between the top of the fescue, and the clay soil the fescue sod is sitting on.

While I have a dugout at the top of the property (about 1/4 mile away), the closest lawn hydrant is broken and I need to replace it.  The pipe is 9 feet down, so a significant amount of digging is needed.  I was hoping to set up a beaver dam analog a little downhilll, which may impound some water over the course of the spring.  Being leaky by design, I don't know how long into the season that water might last.

I an at 56N, my season is pretty short.  It seems to be quite a bit longer than when I moved here in 1975, I think it was described as something like 89 frost free days back then.  Last fall, my first frost was a killing frost; and it was early.

I sourced most of my potatoes from a local Hutterite colony.  They were only described as white or red.  Another of the plots, has some potatoes that are described as originating in the Ukraine or a particular one from Alberta.  I also obtained some true potato seed from Oikos, and that is in a cold frame nearby.  I have been trying to keep the 2 inch pots with the TPS damp, but so far no sign of germination from the TPS.  I built 4 cold frames this year, all are 3'x6' in size.  Three of them have a short side that is 11 inch tall, and the other is 22 inch tall on the short side.  The second day they were in the field, strong winds wrecked the 7kg automatic openers I had on them.  I just recently received a 60kg and a 100kg opener (from Vent-L in Russian Federation) so I am hoping to put them on after the hilling is finished.

I had no idea about yields, and I still have little experience of yields.  But, if I get about 1 pound per square foot, that is apparently consistent with reasonable commercial scale operation.  I think I need to get to about 1 acre of land for potatoes, which means being able to cure and store about 20 tonne of potato.  But that won't be this year.

Oh well, break is over.  Time to get back to work.    I'll take my phone/camera with me, for some pictures.

Last year, it seemed like the top inch of chips became dry, and pretty much everything below that was saturated in water.  And the chips tend to become a light grey in colour, which means a lot of incoming insolation is reflected off (and that the potatoes get light from 2 different directions to drive photosynthesis).

This water saturated layer is insulated from the air temperature and the surface temperature of the chips, by the dry layer on top.  So the temperature of the potatoes and root system should be much cooler.  Which apparently is something potatoes want.

So, my potato strip today had about 2 inches of wood chips on top, so maybe 1 inch of saturated chips.  After hilling, I should have another 3 (or more) inches of chips.  So my saturated thickness should go from about 1 inch to 4 or more inches.

My first picture is of the west end of my strip, where my tallest plant is.


Technically, I haven't hilled this plant anywhere near enough.  But, it ispossible that there are potatoe plants not yet breaking through the surface, and I have just raised that surface all over.

My second picture is a little east, about where I was about to start hilling at that time.


Does the inclusion of images work, I am trying something different than times before?

Preview does not download and show the images, so I still don't know if this will work.

Nope, no images.  Do it the old way.

Again, preview doesn't help.

So, one "full size" pickup load of wood chips did about 200-250 square feet of hilling and about 5 hours (with breaks).  There is a learning curve to everything, so times will come down.  I can't see the "deliver" of wood chips to where I need to use them taking less time, until I get my tractor.

The strip is about 10 feet wide (that was the width of the plastic sheet I had on the field last year).  Working from the side where the truck is, I can easily throw a shovel full of soil with a trenching shovel (this is only about 5 inches wide, but the blade is over 1 foot long) fairly accurately 6 feet or maybe 7 feet.  So, you can get chips to slide up next to the potato plant on the side you are throwing from, and you can do almost that good on the two sides.  But, you cannot get to the back side very well.  This is at 6 or so feet away.  If you are working closer, you can throw from either side a bit, to get nearly all the way around.  Some potato leaves and stems get covered in the process.  Sometimes it is easy to shake them loose, sometime not.

I think for doing the "far side", I will try filling my wheelbarrow with chips, to reduce how much walking I am doing.

Whether I am working with a pickup truck, or a tractor, it is about 6 feet wide and my strips are 10 feet wide.  So there is a lot of wasted space to this.  I suppose once the tractor is here, a person could plant stuff in the area between where the tractor tires will go, which will reduce wasted space.

I haven't looked to see if anyone makes equipment for hilling potatoes in wood chips.  I think if I am going to get to 1 acre of potatoes, I will need to do something.

My guess is some kind of hopper bottom container to put the wood chips in, and underneath that a moving conveyor that is about 4-5 inches wide.  It needs to be able to extend to 10 feet (well, probably 12 feet, since I am not driving on the edge of the strip).  Maybe a joystick is used to control the conveyor?  A person probably wants to be able to control conveyor speed (higher speeds are more material, but it also pushes it forward more - slow speed should fall almost straight down).  Alton Brown always liked multi-taskers on the Food Network, so maybe this is the same machine that places the potatoes on the soil in the spring time?

I've no idea about harvesting potatoes at this point.

I would guess there is some optimal thickness of wood chips.  One of my plots did not place wood chips everywhere this year.  Basically there was a dollop of wood chips where a potato was placed and nothing elsewhere.  That plot is doing lousy at this point.  So, that is less than optimal.  There are too many weeds there, so if nothing significant happens, I will put clear plastic over it and bake it for the rest of the summer and kill some of the weeds.  Clear plastic.  I don't know how I got talked into black plastic, as I can distinctly remember some guy on US public television (Victory Garden?) a _looong_ time ago talking about solarizing soil with clear plastic.

If I put black plastic on the ground, very little light gets to the plants underneath.  The plastic itself heats up, but being black (probably from carbon black mixed into the plastic), it is probably pretty good at radiating heat.  And so things really shouldn't heat up much under the plastic.  With clear plastic, it is nearly transparent in the visible range, so most of the energy makes it through the plastic and is absorbed by the plants/soil/... that is underneath.  Much of that absorbed radiation, is re-emitted as heat (infrared), and the plastic is probably close to opaque for those wavelengths.  So, the heat builds up under the plastic.  We should be able to get things hot enough to sterilize the soil (that is what I had seen on national public television with solarizing soil).

But, I have deer problems.  Deer being white tail deer, mule deer and moose.  None of those animals clips and files their fingernails, and when they walk across the plastic they cut holes in it.

With black plastic, patching a hole such that the black plastic still mostly covers the hole, results in little change in effectiveness.  And it probably doesn't matter if the patch is clear or coloured, or even what colour.  Black would be the best, but electrical tape would be a poor choice for a black patch.

With clear plastic, any hole provides a means of escape for the heat buildup under the plastic.  So patching a hole has to be 100% patched, and it must be transparent.

It would be better if governments everywhere would look to establish deer populations where it isn't forest at 5 deer per square mile.  I only view about half of my farm (so 20 acres, or 1/32 of a square mile).  If I see a single deer on any given day, that is a data point of 32 deer per square mile.  The most I have seen on my farm is 11 in 1 day (352 deer per square mile), and my Mom once seen 15 (480 deer per square mile) in one day.  And I am about 1 mile south of Dawson Creek (population about 13,000).  I suppose a person should keep a diary of how many of these various kinds of deer one sees on every day.  I haven't started.

Where 5 per square mile comes from, is an estimate of deer population such that the biodiversity of the forest doesn't change because deer eat their favorite foods faster than they can be regenerated.  Or so I understand.

Hi Gorden,

It sounds like your busy and facing some challenges. For plastic to smother weeds, black is the best. The lack of light chokes them out, and the black color gets hot enough to cook them. The market gardeners I know, use heavy black trucking tarps, or plastic silage tubes, cut open to make a rectangle tarp. The silage tubes are heavy visqueen, that are black on one side, white on the other. This insures no light gets through, but also can be used black side up for heating up the soil, or white to reflect off the heat.

If you follow the strategy I layed out, in the first post, the heavy mulch will reduce the need for most, if not all irrigation. This will be critical for suppressing the weeds, and creating the fertility, to grow a continually good crop. You will also need to figure out what type of potatos will grow best in your area. Definitely look for short season determinate varieties that will finish up in your 89 day frost free window. Do some resurch, and find a good disease resistant variety. Your local agriculture extension should have some recommendations for varieties used in local organic production. That will get you pointed in the right direction. The beds can be built before last frost, and the potatoes planted, as they will be protected under the heavy mulch from damaging frost: they will also put out roots and creep up through the protected layers of the mulch, giving you earlier establishment. This is of course within reason, so a few weeks before last frost start building them.

They don't have commercial potato equipment for permaculture applications, from my understanding. So my best suggestion is find out the width of your tractor between the inside of your tires. If you can get a tractor with a wide spread thats good. 4 feet would be optimal. The distance between your tires will be your market bed width, and the width of your tires to drive straddled over the rows, will be the pathway width between rows. If your beds are 4 feet wide, plant your rows 2 ft apart, with 1 ft left on each side of the market row bed. This gives you a double row of potatos per market bed. This will allow you to spread your manure, plant your rows of potatos, lay down your wet cardboard, spread the mushroom spawn, layer the hay/straw, and add the woodchips using the tractor, without crushing your seed potatoes. So every 4 ft bed, will have a 1 ft path on each side, before the next 4 ft market bed. You won't need to do any weeding or hilling, just plant and harvest. The extra 1 foot of pathway between double rows, will alow you to walk or drive down the rows with your tractor if you need to spray or treat for pests. Once the potatoes get more mature, they will start to eventually fill in your pathways. Use string lines to help plant straight rows. I would recomend covering you path with at least 8 inches of chips too. The chips will probably spill in your pathways while your building your bed, so it shouldn't be to much trouble to add them there. They will keep the weeds out of the pathways, and help hold in valuable moisture.

Even though you dont consider willow and the others deciduous tree species you mentioned hardwoods, they are a hardwood, meaning use King Stropheria spawn on your cardboard layer. You could make a decent salary on just mushroom sales alone, after they get established, so in case of crop failer on potatoes, you have some income for your labors. With all that acerage your planting, mushroom sales in spring and fall harvests, could cover your time, fuel and seed costs at minimum. After a few years establishing, and with good marketing, King Stropheria mushrooms could be your main crop with all that acerage. So don't miss out on that opportunity, to profit on your efforts, while that mushroom mycelium is making your land extremely fertile. It really is almost necessary for that symbiosis, to creat low maintenance productivity, fertility, and be highly effective in all your efforts.

You can by mushroom spawn online, or over the phone. I think Fungi Perfection is a reputable company, but check out the competition, and see what works for you. You could set up a small bed, following the directions I layed out this summer, then next late winter, early spring when your making all your planting beds, use the old bed from this summer, as spawn on the cardboard layer for your new beds. It will save you money on spawn for establishing beds. Once the spawn gets established in your beds, it will stay there if you keep adding chips every couple of years.

I would recomend crop rotations if possible, and after you plant potatoes in a bed one year, do various types of summer and or winter squash the next year. This will let the bed rest from potential soil born pests. Once a bed has been established the previous year, all you need is a set up on the back of your tractor at 2 ft spacing, so in spring when your reestablishing a potato bed, it acts like a wedge or small plow, to move all the woodchips off to the side, just disturbing about 3 inches of the compost layer, so you can drop your potatoes on the mushroom compost in the little trenches, with perfect row spacing. Smooth it over with the bucket, add your new layer of woodchips to keep it at 8 inches, and your back in business for the year. The cardboard, hay/straw, and manure is only really needed the first year to help establish the mycelium, while fertilizing and suppressing established perennial weeds. Its critical to establishing a bed, but not needed to maintain it, since your not doing high intensity planting, giving your beds the rest of the season to rest, while the mycelium and established biome turn those woodchips into fertility. The manure the first, year helps jump start the soil biome biology, while providing immediate slow release fertility. Once the bed is established, the mycelium will constantly take those hardwood chips, and make mushroom compost, so you won't need much imput beyond adding more wood chips every two years. If a bed gets weedy, or stops producing mushrooms, then do the whole process over.

If you don't have access to hay for bed building, but you have feilds. Maybe someone will hay your feilds, and split the hay with you. Another option is put out an add on Craigslist, that you will haul away old hay or straw. You can also sometimes find people who will give it away, once it gets old. Or see if someone uses straw in their horese stalls, and will give away that straw filled manure. Free manure is also often available on Craigslist, and some places will even offer to load it for free. I would recomend windrow composting, if it needs more aging or pasteurization.

To keep your soil mineralized, many organic farmers will add pure, cheap, no additives, bulk sea salt, at 75 lbs per acre annualy. Personally I would do half that, twice a year in the wet seasons, just because its more gentle on the soil biology.

Those are my best suggestions, I hope it helps.

That method sounds and awful lot of work. I did potatoes in straw for one year, that was solid pottery clay about 1 inch of soil then 1 inch compost and then straw they did as well as the ones in soil except I lost 70% to voles.

An acre of potatoes should give you something like 5-8 ton of potatoes. that sounds an awful lot if you are not selling.

In general I plant my potatoes in Late April early May a month before last frost, we do them about 6 inches down and do NOT hill we are only growing early potatoes so they do not get big and push the soil up exposing themselves to greening. We've dug and sold 60kg from the gate so far and that took up a space about 60m square.

I've had good luck and bad luck with black plastic.  If nothing else, I want to try clear.  But, physics seems to indicate (at least to me) that the clear should let the underlying soil get hotter than with black.  I think the only thing that really gets hot with black plastic, is the plastic itself.

I have an Austrian scythe, a hay rack or two, and a baler that I made from 2x4 and plywood (modelled on the North Carolina pine straw baler).  I have some bales that I made by hand, and I have loose hay that is 2to 3 years old.  So of the land that I cut that hay from, is still not being used.  A problem with this hay "field", is the wild rose content.  Where I had cut it before, the roses are at least small.  Probably doesn't make a difference for starting a garden, but does for feed.

I once tried to make a sickle mower from a B&D hedge trimmer.  But, there was no ventilation and the B^D gave up the magic smoke and died.  I was thinking of removing it from the housing (so that I could add ventilation) and see about replacing the motor at some point.

I've seen the silage bags in fields, never looked at them close up.

In terms of that 89 day number, that was the length of the season when I first moved to Dawson Creek in 1975.  I think we were Zone 2 then.  We are at least Zone 3B now, and possibly Zone 4 now.  But few sources of information for growing season are updating their data.  So, on my TODO list is to get the weather data myself, and analyze it.

Back in that 1975 time frame, the "frost line" was said to be down 9 feet here.  I don't believe it gets anywhere near that far down now.

My neighbour with the cows just dropped by, they are going to be branding cows about half a mile away from us.  That might make a bit of noise (900 screaming cows).  He has some horses as well (100?).  Anyway, he said that if I wanted manure; he can drop some off.  He did tell me who owns the big square bales of rotten pea straw that is on the south edge of town.

Well, it has stopped raining for a few hours, maybe I can do another load of wood chip hilling.

Keep up the good work Gordon, and you'll get these problems tackled! P.S. being in zone 2, I would definitely check to make sure King Stropheria mycelium is hardy enough to handle that. I know its prolific, and goes far north, but I'm not exactly sure how far north, without double checking.

Hope that helps!

Well, I have pretty much finished another pickup load of wood chips, and completed not quite another 20 feet of my strip of potatoes.

The first 20 feet I did was the most well developed, this second 20 feet was probably second best.  There is another 40 feet to go in this strip, and then 4 other areas which  will eventually need hilling.  Maybe.

The short ones in the first 20 feet, seem to have done quite a bit better since I added more wood chips everywhere.  The ones that did the least good, probably grew an inch in the last day or so.  The better ones maybe twice that much.  I suspect that by the time I finish the 80 feet, it might be time for more hilling at the first one.  I wonder if any of the locations where I am not seeing a plant, but there should be one, will respond?

The forecast shows rain tonight and rain tomorrow.

The last part of this 80 foot strip to do, is about 2 weeks behind because I thought it was too wet to plant.  With all this rain, I don't know.  We don't normally get rain like this.

The chips initially are a medium brown and are wet.  In an hour or so, they dry on the surface and become a significantly lighter brown.  I suppose in the days to come, they will bleach to a light grey.

I did see one mouse when I was hilling that first 20 feet, so it is possible that some of the potatoes near the edges of the strip have become lunch for mice.  I suppose voles is possible, as I think they look similar.  I once caught something mouse like in my mouse trap in the garage, and the vole description fit it better.

Some of my potatoes were planted by setting them onto inches deep soil based on peat moss, and then covered with a minimal layer of wood chips.  In quite a few cases, too minimal, as I was adding chips as I seen potatoes become visible.

Peat moss approximates a bunch of fine roots to me.  This bed of peat based soil, has an embarrassingly large number of weeds growing in it,all of which are contributing roots to the peat moss.  Today, I started harvesting potatoes from this planting.  While I sometimes found new potatoes near the surface, they seemed to be in the peat, as opposed to be in the wood chips.  So, I went out with a garden fork, and dug a little deeper.  And there are potatoes down in the peat moss, not remotely at the top.

So, it may be if you place potatoes on "soil" that is in some sense dense, and then cover with 4+ inches of wood chips (possibly adding more during the growing season if hilling seems to demand it); the potatoes do tend to develop in the wood chips, and not migrate down into the denser soil.  But, I never dug into the denser soil, so I could have a herd of 1 and 2 year old potatoes in the fescue sod.

My guess, is that in the absence of a density change/gradient; potatoes will form tubers at heights above, equal to and below the original "seed potato".  If the original planting location allows "above" to make sense.  But  if a sufficiently large density change (or gradient?)  exists, ordinary potatoes will tend to form tubers in the low density surface.

From reading about sweet potato, it will not do this.  Its tubers want to be below the "seed potato" (it has some other name for sweet potato).  I don't know about yam or other tubers.

I've been a little dismayed to see scabs on my potatoes as I am harvesting.  They planting in question was covered with black plastic last year, and before that was fescue sod for 40 years or so.  Some potatoes are nestled down into the fescue.  I haven't gone looking to see if any are down in the clay under the fescue sod.

Scab is apparently helped by high organic matter.  So that might be part of the reason I am seeing it.  This land has probably been fescue sod since WW-II (almost 75 years) or longer.  To walk on this pasture feels like walking on a mattress, there is so much thatch on the ground.  I suspect this is probably the first time potatoes have been grown here, so it is entirely possible my seed potatoes were infected.

I did run across a blurb, which suggests that compost tea might help in reducing scab.  I had been looking into fire blight a while ago, and suggestions seemed to be that a compost tea that was bacteria dominated; sprayed onto apple (pear, ...) trees early in the season might provide enough competition from good bacteria to keep that particular blight at bay.  Perhaps a similar approach works with potato scab?  I am seeing conflicting evidence about how rotation effects scab.

This strip of potatoes I am working on, is nominally 800 square feet.  I have probably harvested 13-14%.  At either end of the strip, are red potatoes.  In the centre are white potatoes.  Some of the white potatoes were planted about 2 weeks after the other, because the ground was too wet.  In the red potatoes, it is looking like about a 4:1 yield.  I need 3:1 to be able to plant the increased area available next spring.  Or buy more seed potatoes.

I suppose another source of this scab bacteria, is the seed bed.  Which is composed of mostly fescue grass (but there is clover, alfalfa, vetch, yarrow, goldenrod, dandelion and various other things in it).  So, perhaps this scab bacteria is in the fescue?  Another possibility, is that the bacteria is in the wood chips (which are nominally aspen, poplar and, but could include other things).

People talk about planting (potato) in wood chips and being able to pull the plant up from the wood chips with the tubers attached.  Not a chance here.  There is so much mycellium in these wood chips, there are mostly glued together.  And at the edges of the plot, living hay is trying to encroach on this land, and it is terribly hard to just pull the wood chips away.

I gather that late harvest potatoes can have new potatoes forming at heights of 6 or more inches above the seed potato (should it have been started from a seed potato).  For all other varieties, the new potatoes are expected to form at a height about the same as the seed potato.

There was a thread by someone on a UBC Botanical thing, which had no comments from anyone.  But, he planted (I believe 2010) potatoes in a narrow/steep trench about 8 inches deep.  And he covered the seed potatoes with enough soil that they were covered, not fill the trench.  At some point, the potatoes grew tall enough that they were out of the trench, at which point he filled the trench with soil (probably loose).  And when the potato plants got a little taller, he put mulch on top.  His potatoes formed outside of the trench, in the mulch.  Or that is how I read it.  So, the stolons from near the base of the potato plant came up the trench walls, because the trench itself was dense soil, and the soil filling the trench was loose, so this was the "easy" path.  And then once out of the trench, the easy path was to sit on top of the soil and under the mulch.  And so, most of his potatoes were on top of the soil.

My ground is covered in thick thatch.  I put a little bit of soil, on top of the thatch.  And set the potatoes onto the soil.  And then covered (with not enough) wood chips.  So, I am seeing some potatoes in the wood chips, but mostly close to the ground, some potatoes are nestled into the fescue thatch, and then a few seem to be "in the thatch".  Close to the border, I am sometimes finding potatoes "in the hay" trying to infiltrate the potato bed (and in the wood chips at the same time).  In the bulk of the planting, I am finding the odd potato with no apparent scab, some with lots and all in between.  A given plant can have scabbed and (possibly) non-scabbed potatoes.  But, what seems to be happening, is that these potatoes that are very close to the edge, tend to be scab free.  Or maybe I am just imaging this?

But it sort of points to the wood chips, as being the source of the scab.  And this might be just because of the woods present.  I suppose another possibility is that the scab was brought in by the earthworms?

While the accepted prescription is to rotate crops, I've seen enough reports that say that for scab problems you probably don't gain anything by rotation.  Grow resistant potatoes.  Acidify your soil.  A hint that compost tea might help (I expect the bacteria dominated ones).

I read a note by a person in Zone 5, about putting fairly think hay mulch over a potato patch for winter, and then removing it come spring.  And someone in Zone 4 writing in to comment, saying he/she had been doing that.  Well, I am borderline 3b/4a  I think (no new data).  So, perhaps I can try putting hay over half of this strip when it is ready for winter?  There are some discard potatoes mixed in with the wood chips which have been pulled aside, and I suspect there could be some hidden potatoes in the fescue thatch.  So, if a bit of hay on top of the wood chips pulled back over top helps; that would be nice to know.

This year is 800 square feet of potatoes in this one strip.  Next spring, I should have another 800 square foot strip and a third strip of about 1000 square feet.  I don't mind that I am harvesting by hand this year, but it would be nice to find some other way next year.  And the end goal is to have about 1 acre in potatoes.

Another thing, this year we had a very anomalous first frost.  On August 8/9, we had a killing frost (-5C).  So, all the exposed potato plants were killed, and the plants usually put up new stalks and leaves from the reserves under ground.  Here at the end of September, I am harvesting them.

Happy harvesting!