Photo: SoraNews24

Pandemic hits sweet potatoes in Japan; prices rise

By SoraNews24

Autumn is the time in Japan where people young and old enjoy the wholesome taste of a sweet potato. Eaten straight from a stone grill or processed into a Starbucks Frappuccino, they are a hearty treat whose taste embodies the season.

However, this year a “foot rot of sweet potato” pandemic has been sweeping the nation. Despite sweet potatoes having no feet to speak of, the parasitic fungus that causes this disease first damages the leaves and stems of the plants, depriving them of nutrients and stunting their growth, but can also progress into the potato itself.

This year 22 prefectures have reported foot rot and the chain of supply has already been experiencing the effects of it. The Kawasaki Nikko Hotel Pastry Shop was all set to make some very special Mont Blanc pastries made with premium naruto kintoki sweet potatoes from Tokushima Prefecture. However, due to the disease, the hotel could not get as many Naruto Kintoki potatoes as they initially wanted.


Supermarkets are currently reporting a 20 percent reduction in sweet potato stock and in some cases prices have gone up by 20 percent. This is because over the year, about 70 percent of farms in Japan have reported cases of foot rot that have affected their supply.

Even farms that haven’t been affected are taking preventative measures that also affect yield. Much like it was during the COVID-19 pandemic, social distancing is being advised for all potatoes in the field. Seed rows are being planted about 10 centimeters further apart than previous seasons in order to avoid transmission of foot rot between potatoes. Unfortunately this also creates less space to grow potatoes and thus fewer delicious Mont Blancs.

▼ News report on the pandemic and its effect on Mont Blancs and prices

China has also been hit with foot rot of sweet potato epidemics in the past year and researchers there are currently racing to decode the fungus’ genome to help find ways to combat it. In the meantime, we’ll have to protect these versatile tubers by relying on conventional control measures such as distancing, maintaining a healthy environment, and putting tiny masks on all the potatoes.

That last one probably won’t help at all, but why can’t we at least have a little fun during all these non-stop problems?

Source: Nippon TV News 24APS Publications

Read more stories from SoraNews24.

-- Typhoon Lionrock delays production of Calbee potato chips

-- “Demon manju”: A low-prep recipe for a delicious regional snack made from sweet potato

-- Falling into the sweet life with Japanese convenience stores’ new sweet potato sweets【Taste test】

© SoraNews24

©2022 GPlusMedia Inc.

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 relying on conventional control measures such as ... maintaining a healthy environment,

Good luck with that. Japan uses some of the highest levels of agrochemicals per hectare in the world.

3 ( +9 / -6 )

If you didn’t catch the obvious, additional advertising plug in the first paragraph, here’s a link: -

“a wholesome taste of a sweet potato….processed into a Starbucks Frappuccino,… a hearty treat whose taste embodies the season” -

8 ( +8 / -0 )

Foul things. Next to Brussels sprouts in their evil effects. If the wife comes back from shopping with them, I’m buying a canary in a cage.

-10 ( +2 / -12 )

-This is what happens when you are not vaccinated.

0 ( +3 / -3 )

Besides ruining the insides, I wonder if this also causes the brown streaks on the skins on the ones that can be sold. The yakimo I have seen look terrible this year. Perhaps too long in the cooker?

0 ( +1 / -1 )

Satsumaimo, Kaki, Daikon, and Yuzu. Things I really do not need to buy but always have a lot of. Yuzu, I have a tree outside my house and use them in beverages as well as make Yuzuburo for my family and give lots to my chonaikai. Kaki, Daikon and Satsumaimo I usually receive people all around my neighborhood and usually never buy these things in the winter time. Sometimes we also receive Kare, Tai, and Buri from Local fishermen. Fall and winter are my two favorite seasons. A another reason why where I live is my favorite place in Japan.

1 ( +4 / -3 )

That would be terrible for me. I eat sweet potatoes all the time. Baked, boiled or in pies. Plus they are cheap as heck here. I never pay more than 200 yen/kilo

0 ( +2 / -2 )

I forgot about sweet potatoes fries and pancakes

0 ( +2 / -2 )

Monsanto will benefit financially whilst ruining another natural food.

Fungus probably feeds on the fertilizer

-1 ( +3 / -4 )

Sweet potatoes are traditional street food often available near temples and at festivals. Some supermarkets cook them outside, either selling them to passers-by, or you take them inside to pay for them. They retain heat very well, so they will still be warm when you get home, even if you have to cross Tokyo, and you can eat the lot, skin and all. As a vegan I'm not the biggest fan of Japanese cuisine, but sweet potatoes are absolutely delicious and very healthy.

Sweet potatoes, botanically unrelated to the spud, once exotic, are now becoming very popular in the UK, with organic ones on sale in supermarkets and slips of multiple varieties available from seed companies. You can grow your own in a tub of compost on a balcony (in the UK or Japan). They can be diced and used to sweeten dishes and store for longer in the cupboard than spuds, making them a useful store cupboard staple.

Fungal diseases come and go, and can be exacerbated by the weather. We should not be worrying about rots or blights in the way we have done about covid. GMO is certainly not the only solution. It can however inform and speed up a natural breeding programme by suggesting the best crosses to try.

0 ( +2 / -2 )

Good thing I personally hate sweet potatoes and would only eat them if I was starving. Chestnuts are a much better winter staple imo.

0 ( +3 / -3 )

Our first Halloween here, we mistakenly gave out full-sized candy bars to the local children and junior high students. In the recent years, roasting 200+ of these became a much more economical and healthy alternative than wasn’t frowned upon by the local elders.

0 ( +1 / -1 )

Hope it doesn't reach here. We grow them every year (Bein Haruka and Naruto Kintoki this year). They are pretty low maintenance while growing and produce a big harvest on a small patch of land. The kids have fun digging them up too.

0 ( +1 / -1 )

ahh sweet potatoes.......where it's highly against the neighborhood rules to have your tv up a fraction above hearing level but perfectly ok for vans (that no one seems to actually go to) to blare ok "YAAAAAAKIIIIIIIIIMOOOOOOOOO" at all times of the day

0 ( +1 / -1 )

Well, it's a good thing I don't like sweet potatoes very much!

-1 ( +2 / -3 )

Its not possible to be a vegan by the way

-4 ( +1 / -5 )

Yuck. A poor person's potato, anyway.

-2 ( +1 / -3 )

Its not possible to be a vegan by the way

Indeed. Without supplements, malnutrition and a deficiency of essential amino acids is a distinct possibility.

0 ( +2 / -2 )

And where does the protien come from originally anyway.

Kill the fish and take the animal poop and bones feed it to the plants and then eat the vegetables .

No animal products there.

Don't accidentally inhale a bug .

1 ( +3 / -2 )

No problem, never liked it

-2 ( +0 / -2 )

my favorite is chicken droppings which has less smell.

lol I had a bagful that the rain got into. The nice, easy-to-handle, not-smelly pellets turned into a thick gooey paste that most definitely does not have less smell. Mixed into the soil it's not so bad, but what's in the bag is .... baaaad. Keep yer powder dry!

No fish or animal bones on my veggies. Lots of pooh, though; chicken, cow and bat, mostly.

I accidentally dug up one of my neighbour's sweet potatoes the other day - it had burrowed onto my side of the border between our allotments, and I didn't see it until my spade hit it. No sign of any disease, it was a perfectly good sweet potato apart from the spade-cut.

0 ( +0 / -0 )

I grew Satoimo this year instead of sweet potato in my garden. Had a bumper crop too. I tried growing sweet potato last year and they all rotted away. I normally see sweet potato for sale near the entrance of the Yaoko or Belc I shop at and rarely do I see people buying them.

0 ( +0 / -0 )

Never learned the conclusion to this story @cleo 4:47pm: Did you have to say “I yam sorry.” to the neighbor?

@cleo 4:47pm: “I accidentally dug up one of my neighbour's sweet potatoes the other day - it had burrowed onto my side of the border between our allotments, and I didn't see it until my spade hit it.” -

0 ( +0 / -0 )

Love the Japanese countryside. Most neighbors are friendly and accommodating. Particularly, those with gardens and the pet-lovers. Always something to talk about.

0 ( +0 / -0 )

*Did you have to say “I yam sorry.” to the neighbor?*

lol The neighbour was nowhere to be seen, so I took the two bits of potato home and Mr. Cleo added them to that evening's menu - the spade cut meant that they wouldn't have kept very long.

Next time I saw the neighbour, I explained what had happened and she apologised for her potato invading my allotment!

Japanese on one side, English on the other...lots of sumimasens and sorrys all round!

when I buy chicken droppings I buy from a local farmer

You're lucky, I have to rely on the local garden centre. The empty bags get spread between the rows, to keep the weeds down.

Invalid CSRF

1 ( +1 / -0 )

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