Hanna Tokyo Pummelo

Citrus grandis (maxima) 'Hanna Tokyo'

Hardy to 10°F, -12°C 

There is one pummelo (pomelo, pommelo) that has been known to survive 0°F, -18°C degrees and come back. The Tokyo Pummelo, a.k.a. Hanna Pummelo, was brought back from Japan in the early 1980's by Dr. Wayne Hanna by way of seed. The mother plant was covered in snow and was full of fruit which caught his attention. He sent seed back to himself and planted it in his yard. Although a very vigorous grower it was set back some years ago after it froze back in 0°F, -18°C weather.

Fruit is the size of a grapefruit, mild flavor.

Sanford Curafora

(Poncirus x Orange) x mandarin?

1/4 poncirus, 1/4 orange, 1/2 mandarin
or 
1/4 poncirus 1/2 orange, 1/4 mandarin

(Citrus trifoliata x C. sinensis 'Ruby') 'Sanford' x C. reticulata?   


Hardy to 17°F, -8°C, or 10°F, -12°C 

Sanford Curafora  is a seedling of an open pollinated Sanford Citrange.  It was selected by Dr. Edwin Frey of Switzerland. The pollen parent is unknown, it is obviously a kind of mandarin, and Bernhard Voss has suggested it is a Clementine.  The whole habit of the plant is mandarin like. The leaves are thin, dark green and attractive, more long than broad and look like mandarin leaves, except for some bi- and trifoliate leaves that sometimes occur. Young growth is frost tolerant. 

Tree sets flowers abundantly, fruits should be thinned,  otherwise it will get only male flowers the next year. The flowers are very fragrant and look more like citrus flowers than Poncirus. The stamens stand free as in Poncirus. They have a lot of pollen and also plenty of nectar.  Perhaps self incompatible, but will set seed with other pollen, indicating perhaps male parent was Clementine. Fruit is  juicy, sweet and with good Clementine aroma. Peel-ability varies. No Poncirus taste. Fruit are late ripening, as late as March, but may be picked as early as December in warmer climates. Similar information plus photographs [1] 

Clementine is either a tangor (orange x mandarin) or  mandarin [2]
When grafted in August, or later, first growths are flowers.  Plants are slow growers.

More comments from May 14, 2014 [3]

Cold Hardiness Table

After a severe winter with a low of 6 F, -14.4 C, Eyeckr reported on the condition of his plants.[1]  This table is derived from his report.  Many thanks for this invaluable information.

3/27/17:
After an extended warm period which saw some citrus setting out new growth, the temperature dropped to 21 F on 3/16/17.  Most citrus saw death of older leaves, in an erratic pattern.  In semi order of hardiness, from high to low.

LEAVES RETAINED:
MIC
Taichang Lemon
Clem-Yuz 2-2
Calamandarin
Nippon Orangequat
Morton
Ventura Lemandarin
Changsha
Thomasville Citrangequat

MIXED:
Juanita
Sunki Kat Mandarin
Ci Clem 10 Golden Lime
SRA 92

LEAVES LOST:
Kimbrough
Taiwanica
Shekwasha
Panzarella Orange
Clemnule
Sancitchang
Ujukitsu
Glen Citrangedin
Hanna Tokyo Pummelo

These results indicate that the plants which remained dormant longest are the most resistant to damage.

Varieties not included here are those that are deciduous or semi-deciduous

And finally,
Comparing Yuzu with Ichang papeda, Yuzu is hardier, Ichang had stem die back and is less vigorous.
These are just basic observations based on small numbers of plants and limited cultural conditions.  Other years/conditions might yield different results.


Extensive list of cold tolerant citrus  Poncirus  data is wrong

US 852

A cross between Changsha mandarin and Poncirus 

1/2 Poncirus, 1/2 Mandarin

Citrus reticulata 'Changsha' x C. trifoliata 'English Large Flowered'

Crosses between mandarins (satsumas) and hardy oranges are called citrandarins.  Citrandarins are some of the hardiest 50% crosses because of the cold tolerance of the mandarin, and Changsha is one of the most cold tolerant of all mandarins.

It was developed as a citrus rootstock.  Patented and released in 1999.  It is Phytophthora resistant, Nematode resistant, and has superior yield when compared to most other rootstocks.

It has fewer seeds per fruit than is desired for a rootstock and about half the seed is zygotic, i. e., does not come true. [1]
Fewer seeds per fruit and zygotic nature of some seedlings have piqued the interest of people looking to grow more cold tolerant citrus. 

A zygotic seedling or mutation of US 852 growing in Northern Virginia [2]  withstood 0°F, -18°C [3], it died to the ground in the severe winter of 2014-2015, it did resprout from the roots.  There was one several years old in Philadelphia, and at least one is grew in New Jersey.  The Northern Virginia tree has almost no Poncirus bitterness [5]

Seedlings of US 852 or from a similar cross [8] are growing in Europe, labeled HRS 899 [6][7]  They have been labeled HRS 899 a, b, c, etc.  They have varying degrees of hardiness, leaf shape, and taste.

Leaves are attractive, shape is distinctive, center leaflet has a longer center than other trifoliate hybrids.   Leaves are also thicker than most citrus and have crenulate margins.

Some spines are long, over 4"or 10 cm in length, but thinner than Poncirus. 

Picked first fruit in November 2016.  Fruit were puberlulent (faint fuzz) from Poncirus parent.  High sugars and high acidity, pronounced bitterness from Poncirus.  When diluted and sweetened like lemons are able to make a pleasant tasting  'ade'.   Brix 14, sour similar to lemon.