Fruit in Korea

I never reported back on my trip to Korea, mostly, I guess, because I hadn't reported back on anything here in months until very recently. But rest assured that I did go, and I did come back, and I did eat fruit while I was there.

Most of what I encountered was not overly exotic, although I did get to try the bokbunja that was recommended in the comments. This is a wine made from Rubus coreanus the Korean black raspberry. It was tasted about like what you'd expect from a black raspberry wine, but with a more substantial kick than I'd anticipated. (Of course, it was followed immediately by a couple of beers at a noraebang, so that might have had something to do with it). I thought it was pretty good. Apparently it also helps with impotence and sexual stamina, though neither was really an issue on this trip.

We also had hallabong, a relatively expensive but very tasty citrus fruit grown primarily on Jeju Island. It's vaguely tangelo-like, released from a Japanese breeding program in the 1970's (they called it Dekopon, but the Korean ones are named for a mountain on Jeju). I've seen a couple variations, so I'm not 100% confident in the pedigree, but the most probable seems to be:

Hallabong = Kiyomi x Ponkan
Kiyomi = Miyagawa x Trovita
Miyagawa = Citrus unshiu
Trovita = Citrus sinensis
Ponkan = Citrus reticulata

(Citrus unshiu x Citrus sinensis) x Citrus reticulata.

(For those unfamiliar with the Latin binomials, sinensis is the sweet orange, reticulata is mandarin/tangerine, and unshiu is the satsuma or mikan.

Anyway, very good. Unfortunately, I didn't get any pictures of it.

I did however get pictures of jujube (from a street market in Suwon):


And some asian pears, apples, and kumquats:

(I don't know what variety of apples they were, but it seemed to be the same variety everywhere. I had one and it was pretty uninspiring).

And some strawberries (there's also a few oranges and melons hiding in there):

(This seemed to be the only way strawberries were sold in Korea–in big styrofoam boxes. I think these were mostly 'Chandler', but I could be wrong (I'm pretty sure at least the ones I ate were). There were a couple of flats that might have been 'Camarosa' or something like that. They were even more shameless than US strawberry packers in hiding the bad fruit under the good, probably because in an opaque container it's easier to hide).

Also, though not a fruit, I also sampled bundagi, silkworm larvae:

(I sampled some of these later, cooked not fresh, and wasn't too impressed, though my cousin told me the ones we had were not especially good ones...)

It's not as far north, but...

...it's a heck of a lot colder than London:

Don's Cold Hardy Citrus

Granted, they're not looking at grapefruit, but I'm duly impressed with anybody who can get an edible Poncirus hybrid. A very cool site, and a good resource for those interested in breeding cold-hardy citrus.

The site is set up in reverse blog fashion, with the new stuff on the bottom, which I find unreasonably distracting and odd.

(Todd Wert, a friend of mine from grad school, pointed this page out to me).

Also, here's a fun-looking citrus page in German, one of the users' pages from the forum page.

Anyone know of any more northerly grapefruits?

From the Home Citrus Growers site I recently discovered:

World's Northernmost Fruiting Grapefruit? (Home Citrus Growers)

Anybody know of anything further north than London (there's a claim for Porlock, but if you're going to make fruiting a criterion I think you have to actually ripen the fruit)? Really I think the UK is probably the only place with a shot at growing it this far north. I've seen some kind of citrus growing in a greenhouse in Iceland (I can't recall what it was) but I think to count it really has to be outdoors...where's the challenge in growing it in a greenhouse...even if it is an immensely cool greenhouse heated only by infernal depths of the earth.

Bizzarria!

It's not hard to see why they named it "Bizzarria":

The Bizzarria Story (Home Citrus Growers)

I've seen a number chimeral citrus specimens before, but I've never seen the Bizzarria before. Apparently it's a graft hybrid of a sour orange and a citron. (Another much less spectacular citrus graft hybrid, Citrus neo-aurantium, can be seen here.).

This reminds me a little bit of the account of the "Sweet and Sour" apple in Apples of New York. Described as a probable graft hybrid, this apple had ridged fruit, with the ribs green and the space in between yellow. When eaten, the flesh in the green areas is tart and acidic, while that beneath the yellow skin is sweet and sub-acid.

Update: The more I poke around, the more I realize that the Home Citrus Growers website is pretty nifty as a whole. I'll add a link in the sidebar, too.

When Citrus Goes Feral

I've posted a few times in the past about the looming threat of citrus greening in the U.S. One of the biggest problems underlying this issue is the staggering quantity of abandoned citrus groves in Florida:

Abandoned Groves a Citrus Greening Threat (The Ledger, Lakeland, FL)

The groves serve as breeding grounds for the citrus psyllid, which transmits the bacterial disease. According to the article, a recent USDA survey calculated that there are 129,869 acres of abandoned citrus groves in Florida, roughly a fifth of the citrus acreage in Florida. That's 202 square miles!

Disease threats like this are hardly possible to eradicate even with careful management, and abandoned groves are everywhere in Florida. As I've mentioned before, the citrus industry in Florida hasn't been in great shape for a while, and greening isn't helping. And although the psyllid and greening are the current focus, feral groves are a ready reservoir for all kinds of pests and diseases.

But although a clear threat, abandoned groves in Florida also represent an opportunity. For one thing, they represent thousands of acres of quality agricultural land, sitting unused. This could be in the form of a new crop, or in rehabilitating the old. By virtue of being abandoned, these groves are basically "instant organic". Companies such as Uncle Matt's Organic have been rehabilitating some of these groves and producing organic citrus and citrus products. Because of the significant premium enjoyed by organics, these groves don't need to attain full commercial yields to be profitable, and a little regular maintenance can make a big difference in keeping diseases and pests from running wild.

(I met Uncle Matt last winter in Florida--he's a nice guy with a quality product. He's got a couple of short videos up about organic citrus growing, and I'm hoping for more in the future--the next one is supposed to be on disease control.)

Blogged with the Flock Browser

More David Karp, this time on citrus greening

Here--before I let another one slip by:

Deadly Pathogen Harms Florida Citrus Groves (New York Times)

I really shouldn't enjoy something so horrible and damaging, but I still kind of get a kick out of the name huanglongbing. I'm so easily amused.

This disease has been hovering on the margins for a while now, having been reported in Miami three years ago, and it was just a matter of time until the panic struck the industry in a big way. And with good reason--unlike citrus canker, which is mostly a cosmetic problem, greening truly ruins fruit and trees. Florida's citrus industry is in bad enough shape already--many growers have sold out to developers in recent years (one grower told me that his kids could work his groves for thirty more years and not make as much money as he could make selling the land, although that was three years ago, before real estate tanked).

This, to me, is a perfect case for transgenics. There are essentially no resistant cultivars, no real obvious cultural solutions (aside from the "plant 'em close together and get what you can before they all die method" which strikes me as dubious and inefficient, and the "plant 'em with guava" method, which seems unlikely but would have the nice side benefit of putting more guava on the market if it did.) Breeding citrus (as I've mentioned before) is not a simple or easy thing to do, and even if it was, varieties capable of truly replacing those currently in place in Florida are almost certainly a couple generations away. Assuming you could convince people to replant at all.

Asian citrus psyllid is knocking on California's door

And where they psyllid goes, so goes the huanglongbing:

Disease-carrying insect poses threat to citrus (San Diego Union-Tribune)

I'm going to be pretty bitter if California winds up with every citrus disease known to man when I had to leave my awesome potted mystery lemon behind to move here. (I did get a tangerine with the new house as a consolation prize, and some day, if they ever get around to ripening, I'll have 'Moro' blood oranges, too.)

One of life's great questions, answered.

I've been wondering about this for a long time:

Origin of 'orange' (Arizona Republic)

(I'm referring to the part about oranges and not the bit about tipping or poisoning birds.)

Australian New Crops Newsletter

Just came across a collection of on-line issues of the Australian New Crops Newsletter, from 1994-2002. Lots of different crops are discussed as well as the practicalities of developing new crops, both as industries and as species.

Here are a few selected articles...I just glanced through and picked out a handful I thought might be relevant to my readers (most are quite brief):

Nashi Fruit (Pyrus pyrifolia)
The Trials of New Crop R&D: Getting the Germplasm
Longan (Euphoria longan)
Kakadu Plum (Terminalia ferdinandiaana)
Edible Indigenous Nuts of Papua New Guinea
Beach Plum (Prunus maritima)
Australian Native Citrus

'Eureka Seedless', a new seedless lemon

Our lemon tree has been incredibly productive this year, so we continually have a basket of lemons sitting in the kitchen and have been giving them away left and right as well, so I've had a fair amount of lemonade and lemon chicken these last few weeks. (I don't know what cultivar it is...a girl in a lab I taught gave it to me in a huge pot because she was moving). I don't see the seeds as a big issue, but people are kind of hyped up about this new seedless lemon, developed in Australia by folks whose plantings have just been completely wiped out by canker eradication (nice to see we don't have a monopoly on that here in Florida):

It's a lemon - without the pips (FreshPlaza)

Of course, seedless lemons aren't that new, really. There was an 'Armstrong Seedless' discovered in 1909, and roughly half a century earlier there was the 'Lisbon'. And the 'Nepali Oblong' probably predates both of them. Not to mention a handful of mystery lemons of undetermined cultivar hanging around, like this one.

Still it's pretty cool.

New Seedless Mandarin Cultivar

The citrus breeding program Univeristy of California in Riverside has released a new seedless mandarin, 'Tango':

Ready to Taste Tangos (The Press-Enterprise)

"Breeding" here is used in the somewhat less strict sense, because there's no plant sex going on...'Tango' is the product of budwood irradiation, which is a fairly common way to induce genetic variation in citrus. (It's not clear to me what the starting genotype was...maybe 'W. Murcott').

Apparently the big improvement here is that the mandarin is truly seedless, not just self-infertile, and remains seedless even surrounded by lots of viable pollen sources.

Fighting Back Against Citrus Canker

Not so long I ago I discussed the losing battle against Citrus Canker here in Florida. This evening I stumbled across an article in the Sun-Sentinel (I think it's Ft. Lauderdale, but through the wonder of the internet there's no need to know) discussing genetic efforts to combat the disease. I don't know if this battle is winnable any time soon, but if it is, it'll probably be won by these people, the folks at the University of Florida research center in Lake Alfred.

I know there are elements out there who aren't going to be happy with any genetic engineering solution, but citrus is one place where standard breeding isn't an attractive option, given the difficulties involved. I have been critical from time to time of the mindset that seems to claim that genetic engineering is the solution to all our problems, and that breeding is an out-dated thing of the past. I think that oversells genetic engineering and undersells the power of breeding. But I think this is the sort of situation that genetic engineering was tailor-made for: not replacing breeding, but solving the specific problems that breeding can't readily solve. In sweet orange you have a crop where not only is it extremely difficult to even get hybrid seedlings, but also an extremely limited germplasm base without the resistance you need anyway. Sure one can, and should work to overcome these barriers and to improve the working material through hybridization with outside species, but that's a long, hard process, and this problem is here, now. And while the magic bullet approach of genetic engineering may not be a perfect solution, it's attainable in the short term.

Citrus Canker declares Victory in Florida?

Well, it looks like we've officially lost the battle against Citrus Canker here in Florida. It's been pretty much inevitable for a long while, but a combination of ignorance, indifference, and selfishness has made it happen that much sooner. And now it's pretty much an inevitability that it'll hit everywhere else capable of producing citrus in the U.S. If we can't keep it from coming over national borders, where we actually have Customs inspectors, there's no way it's going to stop at state borders or "quarantine zones".

The struggle is an old one. The pathogen, Xanthomonas axonopodis pv. citri, was first found in the U.S. after being discovered on imported Japanese seedlings (it's an Asian disease). It quickly spread throughout the southeast, but aggressive eradication procedures led to a declaration in 1933 that Florida was canker free. That stuck until 1986, when it was found again, south of Tampa. A zillion destroyed trees later, it was declared eradicated in 1994, only to resurface in 1995, in a residencial area near the Miami airport. A recurrence in the area near Tampa popped up in 1997, and both areas are now in an ever expanding state of quarantine. (Read more on Citrus Canker here, on APSNet).

The quarantine involves a severe regimen of destroying all citrus within a certain distance of the infected tree, and the latest outbreaks have resulted in the loss of 1.5 million commercial trees and 600,000 home trees. It is this last group that is the likely weak link. Commercial growers know the stakes, and while the loss of a million trees hurts, citrus canker as an endemic pathogen would hurt even more, both in terms of loss of saleable product, and the loss of markets that would follow. Many homeowners, however, fail to appreciate the implications of the outbreak, and there was often resistance to reporting cases and complying with the quarantine. The Miami outbreak, at least, was probably caused by the introduction of infected ornamental citrus in 1992 or 1993.

Now, after years of continually growing quarantine zones, it looks like we might be on the verge of giving up. The USDA is considering hitting the entire state with a canker quarantine, which would be a severe blow to an already struggling citrus industry, preventing them from shipping to a number of states and countries. The alternative is an expanded quarantine zone around infected trees. Realistically, though, this battle is probably over. Although juice citrus, the mainstay of the Florida industry, will be minimally impacted, this will severely damage the fresh fruit industry.

And, sadly, the next big disease fight for the citrus industry is already looming. Citrus Greening (I like the Chinese name, Huanglongbing), a potentially more serious bacterial malady, was recently found in Florida, and has already spread to more than a dozen counties. This one at least requires an exotic insect vector (introduced to Florida already, sadly), so that at least gives us another link to attack. We'll see how this one plays out. I'm not terribly hopeful.

The Grapefruit Family Tree

I was going to post this in repsonse to Gregor Mendel's comment to the Google queries post, but it was sufficiently cool I thought it rated its own post:

The History of Red Grapefruit, courtesy of Texas A&M.

I thought the coolest part was the family tree at the top...I also liked the red/yellow chimera down at the bottom (In fact, I'm going to swipe that photo and make it the Image of the Day.)

A few things I noticed which relate to previous conversation:

Apparently mutation breeding in Texas was performed by irradiating 'Ruby Red', which produced the experimental line, A&I 1-48. A budsport of A&I 1-48 with darker red fruit became the commercially successful 'Rio Red'. I've heard that a lot of what is marketed as 'Ruby Red' these days is in fact 'Rio Red', but they use the other because of the better name recognition (I don't remember where I heard this, so I have no idea if it's true). It seems A&I 1-48 produced a variety of other red sports as well, though I don't know whether any have been released as cultivars...a further sport of 'Rio Red' was named and released as 'Texas Red'.

'Star Ruby' appears to be the seedless result of irradiating 'Hudson' budwood, so there's an example of mutation breeding successfully producing seedlessness in grapefruit, though it's still not a mandarin.

Attack of The Clones

Citrus crops have been with us for a very long time. No one knows for sure how long ago citrus began to be collected and cultivated in it's native range, Southeast Asia, but by the fourth century B.C. it had made its way to ancient Greece, where it was mentioned as a wedding gift of the gods. As any visit to a good-sized grocery store will tell you, there are a stunning array of citrus fruits out there: orange, lemons, limes, grapefruit, pummelos, mandarins,tangerines, tangelos, etc. There are even different cultivars of each of these, making for what seems like an amazing range of cultivated diversity.

Things are not entirely how they seem, though. First of all, there is a tendency to think of each of the different fruits as a different species, and taxonomists have been nice enough to oblige us with species names for each. Taxonomists are in the unenviable position of trying to impose simple distinctions on a system which is neither simple nor distinct, and in this case they create the illusion of many different species, where, in fact, there are basically only four which account for everything you'll ever see in the grocery store: the pummelo, mandarin, citron, and lime. Virtually all the rest are hybrids between these four, some of ancient, probably natural, origin, and some more recent. Here are a few common hybrids:

Lemon = (Lime x Citron)
Sweet Orange = (Pummelo x Mandarin)
Grapefruit = (Sweet Orange x Pummelo)
Tangelo = (Grapefruit x Mandarin)
Temple Orange = (Mandarin x Sweet Orange)
Tahiti Lime = (either Lime x Citron or Lime x Lemon)
Chinese Lemon = (Mandarin x Lime)

You might think that all this intercrossing would quickly result in a wide spectrum of different citrus fruits, rather than these few categories, and you'd probably be right, except for one weird quirk of citrus: it virtually never forms hybrids. Most of these species produce seeds which are what is called "nucellar", which means that rather than hybrid plants, the seeds produce clones of the female (sometimes many, many clones per seed...they're polyembryonic, too). These hybrids are the very rare exception, not the rule.

If you can't make new hybrids, generating new cultivars becomes very, very difficult. All you get is copies of the original. So virtually all new cultivars are the product of mutations.

Take grapefruit, for example: All grapefruits, everywhere, it is thought, come from a single hybridization between sweet orange (Citrus sinensis) and pummelo (Citrus grandis) in Barbados, some time around 1750. Every cultivar, from 'Ruby Red' to 'Marsh' to 'Thompson', is essentially the same genotype, and in fact are basically indistinguishable at the genetic level. When hybrids are made, they suffer so badly from inbreeding depression (after all, a cross between grapefruit cultivars is essentially a selfing) that the plants rarely survive long.

So breeding citrus has become a crazy mix of induced mutations, protoplast fusion, and embryo rescue. Anything to introduce a little genetic variation. And as the usual process of hybridization and selections is basically broken, things like transformation take on added importance for moving genes of interest into cultivated types.

Much of this work is going on at the Core Citrus Transformation Facility at the University of Florida research center at Lake Alfred. Steve Wagar also has a decent page on the various permutations of citrus, and the associated nomenclature.