The most cold-hardy selection tested to date, experts say
Writer: Robert Burns, 903-834-6191, firstname.lastname@example.org
COLLEGE STATION – Satsuma Arctic Frost has been named a Texas Superstar plant by Texas A&M AgriLife Research and Texas A&M AgriLife Extension Service horticulturists.
Arctic Frost is the most cold-hardy satsuma hybrid tested so far, having survived temperatures as low as 9 degrees at the Texas A&M Research and Extension Center test site near Overton, said Dr. Brent Pemberton, AgriLife Research horticulturist and chair of the Texas Superstar executive board, Overton.
The board has named other cold-hardy satsuma mandarins as Superstars: Satsuma Miho and Seto in 2010, and Orange Frost in 2014.
Most citrus are easily damaged by the cold, and can only be grown in tropical and subtropical areas, said David Rodriguez, Texas A&M AgriLife Extension Service agent for horticulture in Bexar County and member of the Texas Superstar selection board.
“Moreover, many of the cold-hardy varieties also have a poorer quality fruit,” Rodriguez said. “However, mandarins and Changsha mandarin crosses have more cold hardiness but better quality fruit.”
Because many satsuma mandarin varieties do well under Texas conditions, they were promoted as a group in 1993, but Miho was the first individual plant selected, Rodriguez said.
“Personally, I promote satsumas around Father’s Day as they make great gifts – you know: a sweet, not sour, citrus for a sweet dad,” Rodriguez said.
They also make great Christmas gifts, he said.
All the satsuma crosses are the work of Dr. Ying Doon Moy, who was born in a small village in south China but immigrated to the U.S. in 1978, said Rodriguez.
Moy found a position as a plant breeder with the San Antonio Botanical Garden in 1980, where until he retired in 1999, and developed more than 150 new varieties of papaya, ginger, esperanza, rose, hibiscus and citrus, Rodriguez said.
In 1997, Moy and Dr. Jerry Parsons, a now-retired AgriLife Extension horticulture specialist, began collaborating to hybridize various satsuma mandarins with winter hardy Changsha tangerines, a citrus variety long cultivated in China. Changsha is one of the most cold-hardy citruses grown there. It produces edible but extremely seedy fruit.
“The goal was to produce a satsuma hybrid with enhanced cold hardiness, as well as a high-quality fruit with a low seed count, and they succeeded,” Rodriguez said.
To make the hybrids, Moy removed the Changsha plants’ flower anthers, applied satsuma pollen, then extracted and nurtured the sexually produced embryo from the Changsha seed.
Seedlings that were viable were planted in containers and allowed to develop and mature for five to seven years, he said.
From the most successful cold-hardy crosses, Orange Frost and Arctic Frost were selected and propagated, Rodriguez said.
In 2005, Parsons and Dr. Larry Stein, AgriLife Extension horticulturist at Uvalde, asexually propagated all of the crosses by rooting cuttings from the original seedlings, Rodriguez said. By 2007, they had plants growing in 10-gallon containers, and proceeded to make trial plantings at Uvalde and Overton to test for cold hardiness in unprotected field settings. Both varieties were made available to commercial growers about two years ago.
“Arctic Frost grows to become a relatively tall tree with white flowers that give off a heady orange fragrance,” Rodriguez said. Come late fall or early winter, Arctic frost produces fruit that is juicy, nearly seedless and easy to peel. It will grow 8 to 12 feet tall in the ground or 6 feet tall as a patio container plant in about five to six years.
“When planting in the ground, protection from cold by wrapping with frost cloth for the first year or two is recommended,” Pemberton said. “A site protected from the north wind will also help with winter survival.”
“The fruit peel and flesh is brightly orange colored, retaining that characteristic from its Changsha tangerine parentage,” Stein said. “The taste is sweet and tart, presenting a true citrus flavor that is missing in varieties that are sweet but bland.”
Rodriguez noted that as opposed to other satsumas, which are grafted to another variety rootstock, Arctic Frost is grown from its own rootstock.
“So if they get nipped back from a hard winter, they do not produce shoots from below the graft,” Rodriguez said. “Folks that have concerns about the cold might do well to size up the tree with a well-defined root system and strong top canopy for three years as a patio plant before transplanting to the ground.”
Texas Superstar is a registered trademark owned by AgriLife Research, a state agency that is part of the Texas A&M University System. More information about the Texas Superstar program, including retail outlets where Superstar varieties may be purchased, can be found at http://texassuperstar.com/.
Along with Pemberton, Stein and Rodriguez, other Texas Superstar board members include Dr. Cynthia McKenney, Texas Tech University, Lubbock; Dr. Mike Arnold, AgriLife Research, College Station; Dr. Dan Lineberger, AgriLife Research, College Station; and Dr. Tim Davis, AgriLife Research, College Station.