Anyone dealt with fusarium in potatoes?

I've harvested four out of the six potato varieties we're growing this year. Last year, we lost about 35% of the Yukon Golds to fusarium, which is a sort of rot in the tubers and may or may not show obviously as a wilting of the above-ground portion of the plant. A section of the tuber, when it was at the worst, looked knobby or caved-in, and blackish. I just burned the affected tubers in a scrap fire.

I acquired all new seed potatoes, and relocated the spud planting area to the far opposite end of our bigger vegetable plot.  So this year, something more like about 5% of the Yukons seemed to have fusarium.

Anyhow, my Warbas and Nicolas, and German Butterballs all had some too, but a little less.  The Russets had virtually none.  I haven't harvested the Lindsers yet.

If you do have fusarium on your land or neighboring land, what kinds of practices have you found to keep your spuds from getting it?

As a side note (apart from the fusarium susceptibility), the Yukons do have very little tendency toward scabbing, unlike Russets, and that's definitely nice.

Fusarium dry rot is both seed and soil-borne and is present in most potato growing areas.
Spread is associated with damage through seed cutting, grading or harvesting.
Wounds created during these processes allow the Fusarium fungi to enter the tuber and spread.

Temperatures of 15 to 20°C and high relative humidity aid the growth of Fusarium dry rot.
Lower temperatures and humidity retard the fungus but dry rot development continues even at the lowest storage temperatures (4°C).

Seed tubers may be infected prior to shipment but not exhibit symptoms until during or after transit. Cultivars differ in their susceptibility to dry rot.

Fusarium species can survive in the soil for a long time as either survival spores or on decaying plant material.
Untreated wounds or cut seed are susceptible to soil-borne infection.
Soil attached to tubers at harvest will generally contain spores that can lead to infection during storage.

Techniques that can be used to minimize dry rot infection are:
For Pre-Planting;

Use clean seed.
Grade out infected tubers.
If cutting seed, sterilize the knife after every bin/box/bag to prevent spread to healthy tubers. Clean shed equipment.
Apply registered fungicides to cut seed. **(USDA recommendation)**
Maintain long crop rotations to prevent build up in the soil.
Bring tubers out of cool- storage and to room temperature slowly to minimize potential damage at planting.
Do not store cut seed for longer than 10 days and keep temperatures below 16°C.

At planting;

Plant when seed and soil temperatures are within 5°C of each other.
Plant seed in sufficiently moist soil to promote quick emergence and wound healing.
Avoid irrigation before emergence to prevent seed piece breakdown.

During the growing season;

Do not overwater.
Monitor and record areas of Fusarium wilt and be aware of these during harvest as they will have large amounts of spores.

At and during the harvesting;

Make sure tubers have good skin set before harvest.
Slow the harvester/grader speed to minimise damage.
Avoid harvesting in wet conditions.
Do not leave tubers in direct sunlight or at high temperatures.
Dry tubers as soon as possible after harvest to aid in soil removal from the tubers.
**((Apply post-harvest fungicides adequately. This is the usual rhetoric from the USDA and all other institutions))**

preparing for and during cool- storage;
Cure the seed appropriately before cool-storage. Maintain adequate airflow throughout the cool-storage to prevent carbon dioxide build-up.
Cool seed gradually to prevent condensation build-up on the seed surface.
Maintain and clean the shed and storage area regularly.
If rot occurs, separate infected seed from healthy seed.

Unfortunately if you have Fusarium disease, most likely it is in your soil and that would require either sterilization of the soil or use of a fungicide.
I have chosen to use heat to sterilize the infected soil. I can rebuild the soil faster than I can get rid of the "cide" residues and thus my land will stay healthy for my wife and our animals.
Since we do raised beds, sterilization of a single bed is acceptable and within the boundaries of possible.

Redhawk
(if you have other questions on Potato dry rot, don't hesitate to ask)

The general handling advice (for before & during planting, and pre-emergent) is good.  Thanks.

My first question might be about whether you know of an effective organic method of detering the fungus from infecting the planted seeds (assuming I've obtained clean seed)?  Lessening the effect on the developing spuds.  I have to take for granted that the fungus is already in my soil, as I know it also is in the gardens & farms in my vicinity.  

You say you're using heat.  Can you describe the heating method you're using, and maybe something about how many years you've gone this route and how it has turned out for you with Solanaceae?

I've been recording my results with different potato varieties, and seeming to find some are more resistant to fusarium infection.

What about acceptable "organic" fungicide types?  Or even brand names?  (Many of the U.S. brands are sold up here in Canada.)  Do you—or others reading this thread—consider fungicides, sold as acceptable for "organic", to be a problem in practice?

The thing is: fusarium is so widespread in North America and the world that I'd think many people doing permie or organic gardening/farming must be dealing with it.
http://www.discoverlife.org/nh/maps/Fungi/Ascomycota/Nectriaceae/Fusarium/map_of_Fusarium.jpg

I haven't had to deal with fusarium yet (it's my first year growing potatoes). But, it's a fungus, yes? Would interplanting something with antifungal properties help? In another thread (https://permies.com/t/70572/Permie-potato-beds#590668) Chris Knott mentioned interplanting

horseradish, which I have heard smells like sadness and death to potato predators, and garlic, because, well, garlic, as well as some French marigolds.  

Horseradish and garlic both have antifungul properties, yes? Maybe they would help? Though, I might be little worried about the horseradish taking over--I hear the stuff likes to take over and is hard to eradicate...

Nicole Alderman wrote:I haven't had to deal with fusarium yet (it's my first year growing potatoes). But, it's a fungus, yes? Would interplanting something with antifungal properties help? In another thread (https://permies.com/t/70572/Permie-potato-beds#590668) Chris Knott mentioned interplanting

horseradish, which I have heard smells like sadness and death to potato predators, and garlic, because, well, garlic, as well as some French marigolds.  

Horseradish and garlic both have antifungal properties, yes? Maybe they would help? Though, I might be little worried about the horseradish taking over--I hear the stuff likes to take over and is hard to eradicate...

Thanks for the post, Nicole.  I've been growing my own organic spuds for well over 20 years.  I've dealt with scab (which tends to develop in spuds grown in soil that is not acid enough).  Fusarium is a relatively new problem for me, though I've recently talked with a commerclal organic grower very near me who's been dealing with it lately, too.

Some kind of intercropping might work... not garlic, though.  One by one, most of the garlic growers in my region have been eliminated from growing it, because another fungus has been destroying their garlic crops.  I had to throw in the towel on garlic about four years ago in our gardens.  Now I trade raspberries for garlic every year.

I guess what I need is advice from someone who's actually been dealing with fusarium, specifically—and been successful with that.

Just adding some additional info to this thread.  First, a reminder that Fusarium dry rot and Fusarium wilt are generally caused by two different species of Fusaria---the first more commonly associated with Fusarium sambucinum and the second being caused more commonly by Fusarium oxysporum.  Some general control measures may affect both, but just a cautionary note that this is not always the case.

Although it's a long haul project, I would encourage noting, in the spring after storage, the "best" looking tubers to use for your garden for that coming year.  Although potatoes are clonal, there is still some genetic variation that likely exists between some of the tubers and by saving the best ones for planting as seed, you may be selecting those that resist the disease better as a consequence.  In addition to possibly improving the genetics of your stock this way, you may also be fortuitously selecting for beneficial microbes on your potatoes that are assisting in fending off attack by Fusaria and other pathogenic fungi.  But also, as you noted, if you are able to find some local potato breeding program that has already made selections for higher resistance to these diseases, that may be a good source as well for new tuber stocks.  Note:  Often the breeding programs will have these stocks but they will not be offered commercially.  Sometimes this is due to the fact that these higher resistance lines don't have the marketing characteristics that the public has come to enjoy....tuber size, roundness, plumpness, etc....so they keep them as breeding material but are not released for marketing.  Doesn't mean that they might not be just what you are looking for and they might not be able to help you in your garden program.

Finally, ... some "light reading" below.  A few selections of information from Wiki and elsewhere regarding Fusarium and the beneficial fungi and bacteria that aid in controlling Fusarium diseases in potato:

https://en.wikipedia.org/wiki/Fusarium_dry_rot
https://en.wikipedia.org/wiki/Fusarium_wilt
https://www.omicsonline.org/open-access/biosuppression-of-fusarium-wilt-disease-in-potato-using-nonpathogenicpotatoassociated-fungi-2157-7471-1000347.pdf
http://jcp.modares.ac.ir/article_620_1d026aafc40ca79db0164e10b412e1b9.pdf
http://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO.1997.87.2.177

Hope there is something of use here.

I like to learn about any fungicide that has been approved for Organic use, many times you will discover that there are not good components in them.
There are several organic certified fungicides though and those should be used sparingly since fungicide use is a lot like antibiotic use, the more you use them, the less effective they become.

Soil fortification is a much better long term solution and this protocol should be used in conjunction with infected organic matter removal/ sterilization efforts for best control.

John brought up a bevy of good ideas/ techniques and reference materials for you.

The ways I've delt with this issue on our farm are; heat sterilization, I literally dig out the bed and put the soil on trays in a wood fired 55 gal. drum oven, this oven is one barrel to hold soil to be sterilized and one barrel to have the fire in, it works great but takes about 20 25 inch long pieces of wood (oak and hickory are what grows on our land so that is what I use). Once the wood is used up (each piece is approx. 20" x 5" x 5") the soil has reached a peak temp of around 750 degrees f and an average of 500 degrees f for 3 hours. I let that cool then bag it until I have all the soil from the potato bed treated, then I place it back in the bed once the new liner is in place to prevent cross contamination from outside soil. The other method I've used is to build a new bed, line it with hardware cloth then a layer of semi-permeable membrane (a special landscape fabric that is tightly woven cotton) and fill that just prior to planting with a good potting mix.
Both of these methods work well for us. Fungicides also work but you still have to do a lot of work to really contain the disease like cleaning up burning or transporting away the infected materials, etc. When I use fire sterilization the infected materials are incinerated as the soil is heated.
Heat treated soil has to become soil again since you created dirt, for that I brew up compost teas and inoculate with fungi spore slurries prior to planting time (about a month ahead).

Redhawk