US-1284, SCS rootstocks

[vnomonee]

I just received two trees that I ordered in the winter for spring shipping from a nursey in Florida 

Has anyone heard of these rootstocks?






Some searching online I found that
The Meiwa is grafted on SCS = Sun Chu Sha mandarin
Are kumquats commonly grafted to mandarins or is the acronym for something else?
It isn't a hybrid with poncirus so I'm not really interested in propagating it. 

The Xie Shan is grafted to US-1284= Citrus reticulata Ninkat x P. trifoliata "Gotha Road" a vigorous poncirus type.

I am going to let a bud of the US-1284 grow out and either root it or graft it to my outdoors poncirus (or both!). It seems hardy to 5f /-15c from what I've been reading. 

[kumin]

US-1284: Fruit length is 4.3 cm, diameter is 5.3 cm. This selection was developed by Kim Bowman as part of a large effort to develop Citrus rootstocks with less vulnerability to HLB.

US-1279, US-1281, and US-1282 developed during the same time period are 100% zygotic in seed production.

List of leaf images including US-1284:
https://rhq.3e4.myftpupload.com/wp-content/uploads/2020/03/Visual-guide-to-USDA-citrus-rootstocks.pdf


List of seed production characteristics:
https://rhq.3e4.myftpupload.com/wp-content/uploads/2020/03/Nursery-characteristics-of-USDA-citrus-rootstocks.pdf

More info:
https://crec.ifas.ufl.edu/extension/citrus_rootstock/tables.html

[Millet]

Sun Chu Sha (SCS) is a mandarin type that has been considered promising as a rootstock in Florida, but testing in California gave disappointing results.  Yields have been lower than trees on Carrizo, but produces a tree about as large as Carrizo.  SCS is susceptible to Phytophthora and citrus nematodes,  but tolerant to CTV.  Its main strength is that it is tolerant to calcareous soils. There is probably little reason to use this rootstock except on calcareous soils.  Info. taken from the Citrus Production Manual.

[citrange]

As you are in zone 7A I presume these will be kept as potted plants.
There is very little relevance in the published information which applies to potted plants.
All the research is directed to commercial growers of in-ground trees.
Tree size will depend to a great extent on pot size.
Cold-hardiness of rootstock doesn't matter if in winter-heated conditions.
HLB and some other insect-borne diseases won't occur.
Soil pH is controlled by whatever planting medium used.
The one thing I find important - unless you are really careful with watering and drainage - is rootstock susceptibility to phytophthora root rot.

[vnomonee]

Thanks all for the info/resources. Seems like a strange choice for the rootstock on the kumquat even for Florida considering the rain and humidity adds potential for rotting, phytophthora looks serious. Perhaps they were out of everything else and that is what they grafted the meiwa to. I will definitely be grafting that over eventually to a pot friendly rootstock. The US-1284 supposedly increases fruit yield up to 2.4x over other rootstocks per one of the published articles I read, but as mentioned the results of the studies don't directly translate to potted citrus   

[Citradia]

As a native Floridian from a citrus producing county, I can say that in FL, rain and humidity are not a problem. The roots will not rot because of rain there. It’s sand. The ground will not hold water unless you happen to live in a very rare muck basin area. I lived in one; one foot below the sand there was thick white clay that you could ball up into a ball and bounce it on our driveway. This was our front yard that flooded in  heavy rains. Our back yard was higher scrub country with sugar sand that held no water. We planted the citrus in the back where wild citrus and palmetto bushes grew naturally.

[vnomonee]

US-1284 on own roots. My graft to poncirus started to grow and then the whole graft died so I only have this plant (plus the rootstock on my potted satsuma). Will test hardiness. No clue what fruit will taste like 😋