JARS v49n1 - Hybridizing for Superior and Unique Azaleas

Hybridizing for Superior and Unique Azaleas
Ivan and Robertha Arneson
Canby, Oregon
in collaboration with
Adele Jones
Lake Oswego, Oregon

Route 99E, south of Portland, runs along the wooded banks of the Willamette River, then cuts away from the water towards the rural community of Canby. If you drive this way in the spring, just before reaching the town, you'll see the green landscape give way to a display of brilliant color: reds, pinks, yellows, oranges, whites. These colorful fields mark the entrance to Ivan and Robertha Arneson's nursery. This first glance encompasses just a small part of the acres of hybrid deciduous azaleas that the Arnesons grow and have developed over the years.

The Arnesons' story began when Ivan and Robertha met while attending teacher's college in Monmouth, Ore. After graduating in 1935, Robertha taught school in a two-room country school near Astoria, on the Oregon coast, while Ivan taught in a country school not too far from his hometown of Canby. After two years, he began teaching in the same school in Canby that he had attended in both grade and high school. When the Arnesons married on June 3, 1938, Robertha taught for one more year and then substituted in the Canby schools for five years.

While he was growing up, Ivan worked for farmers and nurserymen in the Canby area. In 1937, one of these nurserymen, who also had become a fishing partner, planned to retire. Since Ivan had his summers free to work, Ivan approached his friend with the idea of growing fruit trees. His friend offered to help Ivan get started and turn over to Ivan some of his customers. Thus the Arneson nursery began with 10,000 prune trees. Ivan continued teaching until 1946 while getting the nursery established. He then gradually expanded the nursery to a full line of fruit trees. As time went by, he added fruit tree rootstock, shade and flowering trees and shrubs, including rhododendrons. In 1950, the Arnesons bought a 24-acre farm, later adding four and a half acres, which is the present nursery location.
Azaleas entered the Arnesons' story in 1950 when they bought their first Mollis azalea liners. Each year they bought more from various sources. Wade Robbins, who lived on Beavercreek Road in Oregon City, had the best ones at that time, azaleas with brighter colors and good flowers. Ivan picked out and bought the best in Robbins' field for his stock plants, especially several good reds.
In the late forties, John Henny, who lived in nearby Brooks, Ore., visited Exbury Gardens in England. Upon his return, Henny, one of the founding members of the American Rhododendron Society, gave a slide program in Canby, which the Arnesons attended. This was the start of their interest in Exbury azaleas. Henny imported a group of Exbury Gardens' best named varieties, and as soon as they bloomed he cross-pollinated them. By 1956, he had liners available that the Arnesons bought and continued buying for several years.
From the mid-fifties on, Ivan and Robertha began an extensive collection of named Exbury and Mollis azaleas (and some seedlings) from a number of sources. Wade Robbins and John Henny were two major plant suppliers. They also acquired plants from other growers in Oregon: E. J. Kraus, Corvallis, retired professor at Oregon State University; P. H. "Jock" Brydon, Salem, an importer of English azaleas and a founding member of the American Rhododendron Society; Comerford Nursery, Salem, which took over from Brydon. Some sources from out of state were A. R. Hineman, Milton, Wash., another English azalea importer; and Layritz Nurseries, Victoria, B.C., Canada.
The Arneson hybridization program began in 1959. They evaluated the flowers in each set of seedlings they had purchased and labeled and saved the best. This might mean saving only between one and five plants from a cross, although in one cross they saved 15. They then crossed these best plants with a good named azalea or sometimes crossed two named azaleas. The Arnesons' garden began with their collection of named azaleas and all the best of the seedlings they had saved to watch. Each year they added more "best" seedlings to their "watch" garden.

Ivan recalls that John Henny told them to cross only named azaleas, or perhaps to cross a named azalea with a seedling, but not to cross a seedling with a seedling. The Arnesons followed this rule for a while, and then as their judgment and the quality of their seedlings developed they began to cross seedling with seedling. They made many crosses, and as these came into bloom they carefully evaluated them to determine which were the best crosses. This enabled them to choose the seedlings to use for further hybridizing. The Arnesons state their theory thus, "Use the best from each generation to get better."
By the 1980s, Ivan and Robertha were making about 100 crosses a year and selling up to 20,000 plants a year. This large quantity, of course, gave them an increasing chance to select better and better seedlings. They now have collected about 1,500 plants in their garden from all the best ones they've saved in over 35 years of watching and hybridizing.
Just how did the Arnesons develop those bright, clear-colored flowers we see in their nursery? Both Ivan and Robertha had definite goals they were working towards. One goal was to develop intense colors, especially good reds. In the early years, as their liners came into bloom, they selected a large-flowered light red Mollis from Art Wright, Sr.'s seedlings and crossed it with the best red from Wade Robbins. Each year as seedlings bloomed, they saved the best of each lot and planted them in the watch garden. They crossed these with the best from the stock plants and added them to the best of each generation. In 1990, the Arnesons named their best red Mollis 'Robbins Flame'.
Producing a good red flower was not the Arnesons only interest. They tell of another named hybrid that began with some Mollis seed ('C. B. Van Nes' x 'Koster's Brilliant Red'), obtained from retired Oregon State University professor E. J. Kraus. Professor Kraus had a diverse collection of deciduous azaleas from many sources and had made quite a few crosses. When the Mollis seed bloomed, all the plants were various shades of red except one with variegated flowers that had a red bud opening to a red edged flower with a yellow center. Ivan and Robertha crossed this variegated plant with several reds resulting in more plants with variegated flowers. They then planted some open pollinated seed from the original variegated plant. All the seedlings were pinkish except one that was orange-red, opening to orange to yellow-orange. The bees did an admirable job in this case, because this plant was good enough to name: 'Arneson Gem'. The leaf shows some Exbury characteristics.

The Arnesons also obtained some liners from Kraus of a pink seedling x 'Seville' (orange). The seedlings varied from pink to orange and shades in between. Ivan and Robertha selected the best pink one and crossed it with 'Cecile'. They selected the best plant from this cross and gave it the code name CSC1. They also selected the best orange seedling, crossed it with 'Gibraltar' and selected the best plant from this cross. Its code name was CS4G1. The Arnesons have used these two plants as parents for several generations of hybridizing with various other seedlings.
After Kraus died, his collection of azaleas went to various locations. Dr. Robert Ticknor, also of Oregon State University, brought some to the Willamette Experiment Station to watch. The Arnesons obtained several of these plants from Dr. Ticknor. They selected an azalea labeled 35-18 which they crossed with their good orange Exburys and saved the best seven. They again crossed these seven with their best orange Exburys. One plant they named 'Big Punkin'.
Ivan and Robertha became interested in getting better red Exburys. They had some named plants from England such as: 'Royal Lodge', 'Fireball', 'Corringe', 'Knighthood' and 'Renne'. However, these were either small flowered or an orange-red color. They bought liners from John Henny of 'Gibraltar' x 'Favor Major'. They saved the best 15: orange, orange-red and especially the reddest. These they crossed with the named azaleas. In the next generation, one seedling was larger, quite red, and held up well in the sun without fading. They continued to cross the best and reddest plants resulting in a bigger percentage of redder ones in each generation.
Then they added an Ilam hybrid seedling to their hybridizing mixture. Art Wright, Sr., grew this plant from seed sent by John Yates of New Zealand to Howard Slonecker. Wright named the seedling 'Red Hot'; later Slonecker registered it as 'Wallowa Red'. With this addition, the Arnesons finally developed crosses with practically all good reds. They named two: 'Molalla Red' (['Gibraltar' x 'Favor Major'] x 'Wallowa Red' lineage) ¹ and 'Red Sunset' (syn. 'Arneson Red').

A white good enough to name began with a flat of 'Basilisk' x self from John Henny. One seedling was especially nice. This one, when crossed with 'Ballerina', showed some fine white flowers. They made this cross over again for years and finally found a seedling to name: 'Mount Rainier'.
John Henny sold the Arnesons flats of a number of crosses and after saving the best plants and crossing them with the best plants from other sources for several generations, Ivan and Robertha produced more azaleas worthy of naming. Some of the Arnesons' named azaleas with Henny crosses in their ancestry are: 'Orange Splendor' (['Gibraltar' x 'Favor Major'] x CS4G1 lineage) ² ; 'Rose Ruffles' ('Gallipoli' x 'Cecile' lineage) ³ ; 'Canby' (['Gallipoli' x 'Cecile'] x CSC1 lineage) ⁴ ; 'Twinkie' ('Knap Hill Yellow' x 'Klondyke' lineage). ⁵
Another interest of the Arnesons has been to produce petaloid doubles with a larger flower. Every time they found a good flower that was even partly double, they saved it and started to hybridize for a larger-flowered double (corolla 3" to 4" in width). After much hybridizing over a number of years, they have named five: 'Fluffy', 'Frilly Lemon', 'Raspberry Delight', 'Soft Echo' and 'Cascade Pink' (partly double). They are now able to make crosses that produce quite a few doubles.
With the advent of tissue culture technology, the Arnesons have been able to see many of their named hybrids become commercially available. They began working with Bruce Briggs in the early 1980s and now have 15 in production. The first Arneson azaleas available in tissue culture were: 'Red Sunset' (syn. 'Arneson Red'), 'Rose Ruffles', 'Cascade Pink' and 'Fluffy'.
A glowing yellow azalea, named 'Nifty Fifty' (see cover), is currently in production and honors the 50th anniversary of the American Rhododendron Society. This azalea resulted from a cross made in 1977 of a yellow seedling x ('Knap Hill Yellow' x 'Klondyke'). A committee from the Portland Chapter has chosen this azalea along with a specially selected rhododendron, to be introduced at the ARS 50th Celebration Convention, May 1995, Portland, Ore.
What is next? There are still many plants in the Arnesons' watch garden. Ivan and Robertha are working towards selecting a dark, clear red azalea. Over the years, Ivan has set aside a collection of dwarf and semi-dwarf plants for observation. He's found that out of a thousand seedlings grown on in the fields, a few appeared to be dwarfs. These dwarfs he's tested in various ways: by growing them on and using them for hybridizing. He's discovered that some are merely poor plants or runts and these soon die. Others, however, maintain their dwarf traits when hybridized and are healthy, good flowering plants. With the scarcity of dwarf plants in the deciduous azalea world, these plants with their small size and small flowers seem to have good potential for landscaping today's smaller garden spaces. Each year the process of growing and developing superior and unique hybrid azaleas continues at the Arneson garden and nursery.

Adele Jones is a former editor of the Journal and a member of the ARS 50th Celebration Convention Committee.

Registered parentage for the following:
¹ "Molalla Red' {[('Gibraltar' x 'Favor Major') x ('Gibraltar x 'Favor Major')] x 'Wallowa Red'}
² 'Orange Splendour' {('Gibraltar' x 'Favor Major') x [(Unknown x 'Seville') x 'Gibraltar']}
³ 'Rose Ruffles' {[('Gallipoli' x 'Cecile') x 'Pink Delight'] x [('Gallipoli' x 'Cecile') x 'Pink Delight']}
⁴ 'Canby' {('Gallipoli' x 'Cecile') x [(pink sdlg x 'Seville') x 'Cecile']}
⁵ 'Twinkie' (yellow Knap Hill sdlg of unknown parentage x 'Klondyke')