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Journal American Rhododendron Society

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Dr. Glen Jamieson ars.editor@gmail.com


Volume 41, Number 2
Spring 1987

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The Vineland Connection: Parts 2 & 3
A. W. Smith
Horticultural Research Institute
Vineland Station, Ontario, Canada

The Vineland Connection: Part 1 appeared in the ARS Journal, Vol. 40:4, Fall 1986.

Part 2
        The second phase of deciduous azalea breeding at the Horticultural Research Institute of Ontario involved using R. atlanticum as a seed parent. The objectives were to develop stoloniferous plants similar to R. atlanticum, retain fragrance and glaucous leaves, and also produce coloured flowers. R. atlanticum produces white flowers with yellow marking, and has a hardiness rating of -20F to -25F. The use of R. atlanticum as a parent could contribute to extra hardiness in azalea hybrids.
        Using Weldon Delp's method of accelerated growing (ARS Journal Vol. 39:2, Spring 1985), I have been able to flower the F2 generation (R. atlanticum x various Knaphill hybrids) in three years. Seed was sown October first and many plants produced flowering buds within 12 months and bloomed the following spring.
        The F1 generation produced a balanced population of seedlings with little variation in plant habit. The plants that flowered first produced many whites that were of little value. However, as the season progressed some interesting colours appeared. If you like soft yellows and pastel pinks, these hybrids can be easily appreciated. Truss types varied from loose to compact. Some of the less compact forms have an airy grace that would be well suited for the woodlot area. Most of the hybrids retain the pleasing fragrance of R. atlanticum.

        The F2 generation has produced a large segregation of characteristics that have not been fully evaluated at this time. These plants can be divided into four categories:
  (A)  Short and very stoloniferous; no bud set
  (B)  Medium height and stoloniferous; some buds
  (C)  Medium height and little stoloniferous habit; some buds
  (D)  Tall, Knaphill type with buds; no stoloniferous features.
        The flowering characteristics also showed a large variance. Some trusses were flat and others were completely ball-shaped and curving back to the stem. Some trusses had too many florets and appear misshapen. Perhaps the most unusual feature of the F2 generation was the occurrence of an orange coloured hybrid with seven lobes to the floret. Several hybrids have attractive fall foliage. It will be interesting to evaluate the short stoloniferous plants as they mature.

F-2 Hybrid azalea
F-2 Hybrid azalea
Photo by A.W. Smith

        Very few hybrids of the F1 or F2 generation retained the glaucous leaves of R. atlanticum. Perhaps the F3 or F4 generation will produce this trait.

Part 3
        'Calsap' is an example of a hybrid that is hardier than either of its parents. Milton Mitchner of Franklin, Pennsylvania, is the breeder of this fine hybrid. Large plants were on display at the 1986 Great Lakes Chapter show in Cleveland, Ohio, and were much admired by all visitors.

R. 'Calsap'
'Calsap'
Photo by A.W. Smith

        The recent registration of 'Calsap' has been long overdue (ARS Journal Vol. 40:4, Fall 1986). It has won top awards at rhododendron flower shows in the USA and Canada. The registered hardiness rating of -25°C is conservative as Weldon Delp of Harrisville, Pennsylvania, claims it bloomed after -31°F in his woodlot area. This hardiness is enough by itself to warrant attention by rhododendron plant breeders. The striking blotch seems to be a dominant characteristic which is revealed in its new progeny.
        I was fortunate to receive pollen of 'Calsap' from Weldon Delp. After using this in various crosses, some attractive progenies have been obtained at the Horticultural Research Institute of Ontario.
        Needless to say 'Vinecrest' and 'Golden Pheasant' have been crossed with 'Calsap'. I believe that hardy yellows with purple or red blotches will develop in the near future. Thanks again "Mitch" for a fine hybrid!

R. 'Ben Mosley' x R. 'Calsap'
'Ben Mosley' x 'Calsap'
Photo by A.W. Smith

A.W. Smith, Horticultural Technician, has spent much of his life in the pursuit of better rhododendrons and azaleas for cold climates.


Volume 41, Number 2
Spring 1987

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