The Tropical Fruit Forum

I had the premium Yuzu from Japan and candied the peel. When I looked up the process of candying citrus peel it often said to boil the peel to remove the bitter flavor. Because I've heard sometimes that Yuzu peel is not bitter, I did not do this, as I wanted to not lose any flavor by boiling them. But the result of the Yuzu candied peel still tastes bitter. It might be less than most other citrus, I can't compare as I've only candied Yuzu for now.

Was your Yuzu fresh and the peel tender? To use the Yuzu peel, the Yuzu should be fresh and the peel bright yellow-orange in color.
If you bought your Yuzu from a market, outside of Japan, it may have been picked unripe and greenish in color.

At its best, Yuzu zest does have a tiny bit of bitterness, but less than lemon peel.

One of the historic Japanese Citrus varieties ( sorry can't think which ) is said to have been grown from a fruit found on the beach several hundred years ago.

That would be Natsu mikan (meaning "summer mandarin orange", though despite the name, closer to being grapefruit-like rather than mandarin orange). I have actually picked off the tree and tasted one (which I described in another thread). I do not believe this variety has any ancestry from unusual citrus species though.

Something I had overlooked in a different thread.

This may not be completely correct, but from what I understand C. ryukuensis is kind of like a purer ancestor of C. tachibana.
In any case, they are probably very closely related.

Is Taiwan far enough off-shore to be genetically isolated?

I think it would be very difficult for species from the mainland to reach Taiwan by natural means, perhaps not impossible. Most likely any original citrus species that were brought to Taiwan were brought there by humans - the Chinese. (With the exception of C. tachibana which was probably indigenous to either Taiwan or Southern Japan, or perhaps both)

The island of Taiwan is 160 km (about 100 miles) away from mainland China. And probably most of the citrus types did not even exist on the coast of China in that area before the Chinese civilization came, with the exception of kumquat.

There are about one thousand endemic plant species in Taiwan, meaning they exist only on Taiwan, not the mainland. So this would seem to indicate some degree of natural genetic isolation.

According to one ancient text, mandarin oranges could be found growing in the wild on the island of Hainan by around the year 1000 AD, though it is unlikely the species originated there. (Edward H. Schafer, Shore of Pearls: Hainan Island in Early Times, University of California Press, Berkeley, 1970 )
They probably escaped into the wild from human cultivation.



Forestry Bureau held a "Return of the Nansho Daidai Sour Orange" event at the hiking trail entrance of the Daping Forest Road of Jiali Mountain in Nanzhuang Township, Miaoli County. Planting of the Nansho Daidai Sour Orange took place at the event, where it was also pledged that this citrus species will be brought back to its place of origin (this citrus, named after Nanzhuang, is an endemic plant of Taiwan and is now on the verge of extinction in the wild). It is the hope that this act can help restore the forest ecosystem in the foothills of Taiwan and promote the development of green economy in the mountain village communities.

The Nansho Daidai Sour Orange (Citrus taiwanica Tanaka & Shimada) is a citrus species in the Rutaceae family endemic to Taiwan. It was first documented that the plant was discovered in 1926 by Japanese botanists in Miaoli's Nanzhuang Hongmaoguan, present-day Penglai Village in Nanzhuang Township, and was therefore named "Nansho Daidai Sour Orange." However, with the development and utilization of the foothill forests, the Nansho Daidai Sour Orange almost become extinct in its original discovery site, and it has been listed in the IUCN Red List as a Critically Endangered species due to its rarity.

The Penglai region in Nanzhuang is the traditional living area of the Saisiyat people. According to Gen Chih-You, a Saisiyat elder, the Saisiyat name for Nansho Daidai Sour Orange is gadayou (meaning "food prepared by mother"). The citrus has been an important plant for the Saisiyat since ancient times, since the fruit is both a snack and also has medicinal and ceremonial applications. Elder Gen recalled that when he was a child, whenever he had a cold, the family elders would grind dried Nansho Daidai Sour Orange into a powder for him to take as medicine. It was a must-have plant for general healthcare used by every Saisiyat family in the early years when medical treatment was not readily available.
According to the Forestry Bureau, the fruits and leaves of the Nansho Daidai Sour Orange have a strong fragrance, while the juice has a distinctive sour taste and a slight bitterness. The fruit's unique flavor makes it very suitable for processing and consumption. Furthermore, the wood of the orange tree is extremely fine in texture, and according to literature, it was considered the best wood for making pipes, knife handles, and other delicate wooden tools in the early days.

The fruits were tested for the development of essential oil extraction, dessert-making, and tea and beverage preparation, all with amazing results. At the event, the Hsinchu Forest District Office presented a "pound cake with Nansho Daidai Sour Orange frosting" made using the juice and "Nansho Daidai Sour Orange peel nama chocolate" made using the orange peel syrup. The unique refreshing scent and tangy sweetness of the Nansho Daidai Sour Oranges greatly impressed the guests who tasted the delicious treats. It is hoped that the local tribal communities of Nanzhuang will create specialty products with Nansho Daidai Sour Oranges, as it would not only help with both species preservation and the economy, but also bring a wonderful flavor experience to the people of Taiwan.

"Return of the Nansho Daidai Sour Orange": Forestry Bureau Partners with the Saisiyat to Restore Taiwan's Endemic and Rare Plants
from Taiwan, January 29, 2021
https://www.forest.gov.tw/EN/forest-news/0067054

(It should of course be noted than Nansho daidai was already a cultivated variety in Japan in old times, before being found by the Japanese botanist growing in the wild in Taiwan. It was valued in Japan as an ornamental because the fruits continue to hang on the tree for a long time, sometimes up to several years)

I am not saying this is applicable to all climates, but from what I have seen in the climate where I am, from several Yuzu plants, maybe about 11.5 degrees F ( -11.35 degrees C) might be the limit of what Yuzu can survive, over consecutive years. At 14 degrees F ( -10 degrees C) it will suffer virtually no damage. Below that it will suffer some partial damage. The plant might be able to survive down to 10 or 11 degrees F with serious damage, but will not be able to sustain that year after year. Not in this climate. Maybe somewhere farther South in the U.S. with a longer and warmer growing season it might be able to recover and not slowly decline from that.

My Dunstan citrumelo appears to have more cold tolerance than my Yuzu and can survive better. The leaves will be more likely to fall off, but they can regrow easier. Yuzu does not regrow leaves as well. It's important that the Yuzu keeps its old leaves because it might only grow 30 or 40 percent the number of new leaves the following year as the number of old leaves on the tree. The leaves do appear to be able to recover from partial damage, and can regain some of their green coloration, but if damaged beyond a certain level, they will eventually fall off, often this may not become fully evident until later when things begin warming up.

I would like to point out that these numbers are really not exact, and are more based on my subjective impressions and instincts I have gathered from experiences, with several plants over several years. So I hope that just helps give some anecdotal idea, rather than being taken as exact reliable information.

The Ichangquat I have should be the same one as Ilya's, which for him has survived unprotected in zone 8a for 15 years or more (I don't know exactly when he got it). Which included temperatures down to -16°C I believe (3.2°F).

It seems the Ichangquat cultivar 6-7-2 is the one that is most cold hardy, while others aren't as much. Although the one we have in Europe is an F2 from 672, so I'm not sure how the US and EU versions of 672 would compare.

Yes, the seeds came from Ilya, but one thing to consider is that Ilya's tree is growing in a very protected spot on the inner corner of two high walls of his house. 
Another factor might be the climate. I suspect there may be something a little bit different about Europe (specifically France's) climate compared to the U.S. PNW. Although the PNW region and France are very similar, zone 8a in Europe may translate to more stable temperatures with fewer ups and downs than in the U.S. I am not sure. It seems many have had more success with varieties in zone 8a Europe than I have had with those varieties here.
Ilya also lives not too far from Paris, which might further be helping, preventing things from getting too cold.

What kind of temperatures did you have when your plants got wiped out?

It went down to almost 12 degrees F, maybe only 14 degrees F (let's say -11 degrees C ),  buried in a foot of snow.
This was preceded by a clear sunny day. Perhaps the sun is a little bit more intense here than in Europe, and that is enough to warm the leaves too much, maybe reducing the level of protective dormancy? The latitude on the planet is not much different (47 degrees north here compared to 48.8 in Paris, which could still make some significant difference), but perhaps the skies here can get a little bit more clear sometimes than in Europe during the winter. I am not sure, it is very likely I am just overthinking this.

Some varieties that seem like they may be able to make it here gradually decline year after year until they finally die.

I tasted the Morton citrange and Thomasville citrangequat that Jim VH grew. (We think it is a Morton citrange because the fruit strongly resembles it and does not resemble any of the other hardy citrus varieties we are aware of, and the nursery where the tree was bought used to sell Morton citrange and we believe there could have been a mix-up) 
The Morton citrange looks like a delicious orange, few seeds, but has a terrible poncirus taste inside that makes it completely inedible, to me in my personal opinion.
The Thomasville citrangequat was completely edible, in my personal opinion, with little bitterness and barely any detectable poncirus off-flavor. The flavor was rather lime and calamondin-like, but a little inferior in flavor to a regular lime.

I think Citrangeremos are hybrids between Eremocitrus x Citrange.

Let me first say I am not expert in this specific area, but from what information I have found, I believe that Citrus glauca is only about equal in cold tolerance to Satsuma mandarin. (Even though Satsuma mandarin can be rather cold tolerant in some situations)
This makes me skeptical that Eremo- hybrids with ordinary citrus fruit species could be as cold tolerant as claimed.

I do know that Citrus glauca is very drought tolerant, so that might potentially resist desiccating cold winter winds, and perhaps it enables the root systems to sprout back.

Of course, the person who made the opening post lives in climate zone 8b, so I am sure all sorts of only marginal hardy citrus varieties could survive there. Even a Satsuma mandarin might perhaps survive for him if planted in a protected spot. If he lived in 8a, it would be very much more difficult, and zone 7 nearly impossible.

It should also be noted that there is a big difference between zone 8 in the US South versus zone 8 in Europe. (Given the same climate zone number, I think the South is easier to grow in most years, due to the longer growing season and greater warmth)

I thought that sudachi is significantly less cold hardy than yuzu? Still better than most citrus, but closer to the level of a satsuma?

From my testing 2 hours north of jim VH, it seems like Sudachi has close to the same level of absolute cold tolerance. But Yuzu is a more vigorous grower and can more easily recover from damage. The Sudachi and most of the Yuzu plants finally died after being exposed to a brief temperature drop to 9 °F, even though the rest of the winter wasn't that cold. They had previously survived a quick drop down to between 12 and 14° a previous winter, with only slight to moderate damage.

Two small updates

One of the Yuzu bushes that I thought was killed seems to be sprouting a few tiny leaflets from its base, right above the graft line.

A seedling that I grew from US-852 citrandarin (poncirus x Changsha) seems to be sprouting up from the ground. I had presumed it was killed back to the ground by the winter, but it is possible my gardener carelessly wacked it down. It is planted in a shady colder part of the yard where hardy citrus has not seemed to do well.

It does appear that I see some green at the very base of one of the Ichang papeda plants, close to the ground. I don't know if it will be able to grow out.

If it's that tall, it should be producing blooms by now. My guess is it's a combination of both being a seedling tree (by that I mean growing on its own roots, no dwarfing effect from being on grafted rootstock) and the climate (recovering after the winter making it more reluctant to bloom).

It did not do well for me in the US Pacific Northwest, zone 8a. It was obviously less cold tolerant than Yuzu. It was almost completely killed, but managed to hang on to life for three years, slowly declining until it finally died. After the first winter it lost all its leaves, and I could later see the next two Spring seasons that the plant was trying to bud out leaf growth in two areas, but the plant was just not successful, and so the plant began declining since it was not able to grow out any leaves.

I would guess this might be a variety fit for a protected spot in zone 8b, or might be useful for further breeding purposes.

It might be able to survive in a protected spot in zone 8a in the US South. I don't know.

Why would my 5 ft tall Seville sour orange tree have fruit that won’t ripen after a year and a half?

This is not unusual if the tree is still small, and especially if it is in a Northern climate with a shorter growing season.