US-802 citrumelo

[Perplexed]

Citrus grandis 'Siamese' X Poncirus trifoliata 'Gotha Road' https://citrusvariety.ucr.edu/crc4266

When used as a rootstock it makes a vigorous tree and extremely large tree. I see that it's crossed with Siamese pummelo, which could either be the acidless version or the other siamese pomelo, as they have two accessions of siamese pomelo. It would be interesting to use this in crosses instead of dunstan since it may carry acidless in the gene pool if it uses the siamese acidless pomelo 🤔

[mikkel]

looking at these pictures I had the idea it might be a polyploid.
https://idtools.org/citrus_id/index.cfm?packageID=1179&entityID=8884
I have a polyploid citrumelo chance seedling that grows like crazy. Even in my climate.

Anyway, if 802 is from Siamese Sweet, it sounds interesting for breeding. But I rather suspect that it is a standard Siamese offspring (but that's just an idea I had when I read about it on the internet).

Probably hard to get? or can you order it from UCR?

[Perplexed]

Hard to get, not listed as available from UCR. I have a tree I bought from a nursery that is actually using this as the rootstock, but the tree is a Trifoliate+Satsuma. Not gonna decapitate it for US 802.

[caladri]

No viable buds on the rootstock which you could bud onto something else?

[a_Vivaldi]

Perplexed, I have a satsuma from the same nursery I suspect, as it's on US-802. This spring the rootstock put out two strong suckers. I'm either going to let them grow and fruit, or take material and graft that into something else. Either way, I'm thinking I'll have some US-802 fruit to test in a few years.

[caladri]

CCPP has US-802 as VI 1499, and should have budwood available at some point in the not-too-distant future, albeit not available for ordering as-yet.

[a_Vivaldi]

The pumelo parent on this one sure comes through in terms of growth habit and vigor. Last year I put in a satsuma on a US-802 rootstock. This year, given that this is a fairly unknown trifoliate hybrid as far as fruit and seed are concerned, I decided to let two suckers grow. One I grafted ichang papeda to, the other I let grow.

It grew.

Can I say, waterspout?


I tipped it right at 6 ft to encourage branching.


The four branches were initially well shaped, but have started leaning a lot more than I'd like. Still, 20 in. ain't bad on something that already shot up 6 ft in one summer. And it's still just August, so I can expect a bit more growth I think (I really hope I get some more stem thickening, trying to be really hands off with the support and just use the bar minimum to ensure I don't lose the whole thing to some wind or snow).


The crotch section looked really weak for the first few months, but it's thickened up a lot since and I think it'll be alright. Crazy to think that the big ol' green thing, now the thickest of the plant's three trunks, didn't even exist six months ago.


The locals carefully guarding it.


Ichang papeda graft looking happy.


The satsuma probably feels like there's been an invasion of privacy. Despite that, it's managed to grow a bit itself and has held onto its first fruit.

[a_Vivaldi]

Update on the US-802

We've been below freezing for about two days now, maybe a little more, and have had a low of 10 F (6 F in exposed parts of my yard). This photo was taken this morning while temperatures were still well below freezing. Aside from a little winter yellowing, the leaves of US-802 appear unfazed and undamaged. In contrast, Dunstan is showing severe leave curing and will probably defoliate. US-1516 looks good too, but it's hard to tell since deer ate almost all the leaves off them for some reason.

I suspect US-802 is in fact quite hardy.

[Wahl]

That is a amazing. Did you cover it or heat it in anyway? I need to try one here, do you know where I could get one?

[a_Vivaldi]

That is a amazing. Did you cover it or heat it in anyway? I need to try one here, do you know where I could get one?

The bottom portion is covered with a single layer of tarp, mostly just for wind protection for the satsuma that's down there. In some of my earlier posts you can find a picture of the whole plant to see what I mean. But the whole top half of this one was completely exposed. It's far to tall, and thorny, for me to try and protect.

Unfortunately, I haven't seen it come up at any of the usual sources. I chanced to get this one as a rootstock for a satsuma I bought from Just Fruits and Exotics and decided to let a waterspout grow. I'm hopping it'll fruit this year, both because no one seems to know what the fruit is even like with this variety, and because then I'll have seeds (which should be mostly or entirely nucellar). And of course I'm hoping to use to pollen, so I need it to bloom for that.

[bussone]

US-1516 looks good too, but it's hard to tell since deer ate almost all the leaves off them for some reason.

The answer to the question: "Will deer eat it?"

Is "Yes."

[a_Vivaldi]

US-1516 looks good too, but it's hard to tell since deer ate almost all the leaves off them for some reason.

The answer to the question: "Will deer eat it?"

Is "Yes."

...but only the US-1516 for some reason. I have two of them, both completely leafless. None of the other citrus have been touched. So strange.

[Till]

The fruits of US-802 seem to be sour. See https://idtools.org/citrus_id/index.cfm?packageID=1179&entityID=8884
A cross between Siamese Sweet and Poncirus is supposed to be about half as sour as Poncirus what would still be sour. So I do not clearly see whether US-802 comes from Siamese Sweet pumelo or just Siamese pumelo. An additional problem is that idtools.org has always only very limited taste descriptions. They state for example for Morton just "sour". "Sweet-sour" would be much more appropriate. If US-802 is sweet-sour then it could well come from Siamese Sweet.
I wonder, however, that official descriptions of the rootstock only state that it comes from "Siamese pumelo" and never say "Siamese Sweet".
UCR Riverside differentiates between Siamese Sweet and Siamese. Cf. https://citrusvariety.ucr.edu/citrus-varieties/alphabetical-order#s

[Mulberry0126]

I'm not sure how useful this is, but looing at the chemical composition of US-802, it lacks β-Pinene (pine-like taste) which US-942 contains in much greater quantities; it has similar amounts of α-Pinene though. It also contains more β-Myrcene, o-Cymene and other chemicals which can contribute to sweet, earthy, spicy, minty, woody, and carrot-like tastes. I'm curious how all of this actually factors into the flavor. I'm no expert on volatiles so perhaps someone with more knowledge can better interpret these results.

https://www.mdpi.com/2079-7737/10/12/1285

[SoCal2warm]

I'm not sure how useful this is, but looing at the chemical composition of US-802, it lacks β-Pinene (pine-like taste) which US-942 contains in much greater quantities; it has similar amounts of α-Pinene though. It also contains more β-Myrcene, o-Cymene and other chemicals which can contribute to sweet, earthy, spicy, minty, woody, and carrot-like tastes. I'm curious how all of this actually factors into the flavor. I'm no expert on volatiles so perhaps someone with more knowledge can better interpret these results.

Unfortunately it is probably not very useful. That terpene profile analysis probably gives some limited idea of what sort of direction in aroma those fruits have, rather than being an indicator of how good or acceptable their flavor and taste might be.

Myrcene is a very dry "woody" smell, almost "floral" in a certain sort of subtle way, that is reminiscent of the peel smell of grapefruit, before it has been cut. I do not mean that it really smells like grapefruit, but rather its smell is reminiscent of a component in the smell of grapefruit or pomelo - a part that goes into composing the overall fragrance.
cymene does not really smell that good, in my opinion. It's sort of like a very "flat", "oxidized", sour and inferior version of limonene (and sort of half between the feel of D-limonene and L-limonene). Caryophyllene oxide is a spicy warm virginiana cedar cigar box - more in the direction of dry wood shavings - incense smell.
Many of these poncirus hybrids probably do smell fragrant, but in a more woody, floral and perfumed sort of way more so than an aroma that brings to mind edible citrus. And many of them do also have a slightly "skunky" smell (but not in a terrible way).
When you think of terpenes, think of patchouli, strong hops that go into beer, or cannabis smoke, those type of smells. So these poncirus hybrids will be higher in that type of smell than ordinary edible citrus.

The analysis also found the hybrid fruits were high in neohesperidin, which is the substance that causes grapefruits to have a bitter flavor. It is not desirable for edibility.

The paper does say this:

Although first-generation hybrids of Citrus with Poncirus typically have fruit with undesirable flavor, they may be suitable for the production of many secondary processed products with high value.

So the paper had nothing to do with evaluating the fruits for flavor or edibility.

[Mulberry0126]

I'm not sure how useful this is, but looing at the chemical composition of US-802, it lacks β-Pinene (pine-like taste) which US-942 contains in much greater quantities; it has similar amounts of α-Pinene though. It also contains more β-Myrcene, o-Cymene and other chemicals which can contribute to sweet, earthy, spicy, minty, woody, and carrot-like tastes. I'm curious how all of this actually factors into the flavor. I'm no expert on volatiles so perhaps someone with more knowledge can better interpret these results.

Unfortunately it is probably not very useful. That terpene profile analysis probably gives some limited idea of what sort of direction in aroma those fruits have, rather than being an indicator of how good or acceptable their flavor and taste might be.

Myrcene is a very dry "woody" smell, almost "floral" in a certain sort of subtle way, that is reminiscent of the peel smell of grapefruit, before it has been cut. I do not mean that it really smells like grapefruit, but rather its smell is reminiscent of a component in the smell of grapefruit or pomelo - a part that goes into composing the overall fragrance.
cymene does not really smell that good, in my opinion. It's sort of like a very "flat", "oxidized", sour and inferior version of limonene (and sort of half between the feel of D-limonene and L-limonene). Caryophyllene oxide is a spicy warm virginiana cedar cigar box - more in the direction of dry wood shavings - incense smell.
Many of these poncirus hybrids probably do smell fragrant, but in a more woody, floral and perfumed sort of way more so than an aroma that brings to mind edible citrus. And many of them do also have a slightly "skunky" smell (but not in a terrible way).
When you think of terpenes, think of patchouli, strong hops that go into beer, or cannabis smoke, those type of smells. So these poncirus hybrids will be higher in that type of smell than ordinary edible citrus.

The analysis also found the hybrid fruits were high in neohesperidin, which is the substance that causes grapefruits to have a bitter flavor. It is not desirable for edibility.

The paper does say this:

Although first-generation hybrids of Citrus with Poncirus typically have fruit with undesirable flavor, they may be suitable for the production of many secondary processed products with high value.

So the paper had nothing to do with evaluating the fruits for flavor or edibility.

Thank you, this is helpful information. It's probably not useful enough to study on its own, but it would be interesting to see these fruits evaluated for flavor alongside volatiles.

[a_Vivaldi]

Mulberry0126, in reference to our conversation.

[Mulberry0126]

Mulberry0126, in reference to our conversation.

Looks good to me! With the vigor this plant is displaying, I will be curious to see how long it takes to fruit after being grafted on a good-sized trifoliate rootstock.

[a_Vivaldi]

US-802 is putting on its second or third major flush of the summer. I've had a few new shoots break off unfortunately, which seems to be an issue with a lot of citrumelos (Dunstan does it the most so far). Despite that, and some pretty heavy pruning for scion wood and to clean up the structure, the tree is growing well.

A low of about 12 F this past winter did no harm at all, the plant didn't even defoliate. In contrast Dunstan had some twig die back and a lot of yellowing, some defoliation. So even though it's trifoliate x pumelo rather than trifoliate x grapefruit like Dunstan, it's considerably hardier.


Photographed from a ladder...


Pushing past 9 ft tall, was around 7 feet tall at the start of spring iirc. I expect to reach or pass 10 ft by the end of this year. Really hoping it fruits next year.


Some of the new growth that broke off. Given the tree's height, I don't tip the new growth like I do for other citruses that have breakage issues. Unfortunately, that can mean when the new growth does break off, I lose pretty significant amounts of growth.


Decent caliper, though maybe not as much as I'd expect given the plant's size.