New, improved dogwoods add strength and variety to beauty
Breeders have jumped in to create anthracnose-resistant cultivars.
Special to The Seattle Times
Local news partner - Plant Talk
Valerie Easton writes in her blog about gardens and the people who make them.
WHAT IS IT about dogwoods? Their subtle flowers dominate the city scene in springtime, from the groves of Cornus 'Eddie's White Wonder' in the Olympic Sculpture Park to the dogwoods lining Roy Street on Queen Anne Hill. Their bloom is neatly sandwiched between ornamental cherries in early spring, and summer-flowering trees like magnolias and crape myrtle.
I grew up in dogwood heaven in Lake Forest Park, where our native dogwood (Cornus nuttallii) formed a blooming understory to all the firs and cedars. This tall Pacific dogwood with exquisitely simple, cream-colored flowers is native from British Columbia to the mountains of Southern California. By the late 1970s, native dogwoods began to show signs of the fungal disease anthracnose, a scourge that disfigured and decimated these beauties over the next decades.
Breeders have jumped in to create anthracnose-resistant cultivars, often with C. nuttallii as one of the parents. I find it comforting that our native dogwood's genetic material lives on in trees like C. 'Eddie's White Wonder,' a cross between the Pacific dogwood and C. Florida, the Eastern dogwood. The result is a smaller, profusely flowering tree that is proving to be disease resistant.
There are so many new dogwoods hitting the market, many with variegated leaves, that I can't keep them straight. White, gold and yellow variegation, even tricolor leaves, are showing up. Why are breeders spending time and money to develop more and more kinds of dogwoods?
I asked Gary Handy, of Handy Nursery Company in Boring, Ore., where they've been playing around with dogwood genetics since the 1950s. Handy is a big fan of Asian, or Korean, dogwoods (Cornus kousa) because they are highly, highly resistant to anthracnose as well as powdery mildew. "Cornus kousa bloom later in the spring, and for four or five weeks. You get big, showy fruit in summer and good fall color. And as the tree ages, it has winter interest, too, with patchy, flaking bark," says Handy.
Breeders are selecting for trees with full, overlapping bracts. The flower on a dogwood is just the little reproductive part in the middle of the bracts, which we think of as the flowers. Handy suggests we should keep an eye out for the new "super-hybrid" Cornus 'Venus' with bracts seven to eight inches across. In late May, the tree is covered in blooms as big as the palm of your hand, creating a fluttering, white-hanky effect. 'Venus' is part of the Stellar series of dogwoods bred by Rutgers University for disease resistance and flower power.
And which of the variegated cultivars does Handy recommend? "C. kousa 'Wolf Eyes' is the most popular in the Northwest, where it does really well," says Handy. 'Wolf Eyes' is small, shrubby and likes shade, where it will light up a dark corner with its white-splashed leaves. The flowers are pale green and the fruits bright red and raspberry-like.
Dogwoods sporting gold and yellow variegated leaves warm up the garden on overcast days. The award-winning C. kousa 'Summer Gold' is probably easiest to find in the nurseries; Handy also recommends the cultivar 'Celestial Shadow' for the rich yellow of its variegation and 'Gold Star' for its spreading, open shape.
The innovation continues apace. Breeders are working on dogwoods with weeping shapes, yellow fruit and purple leaves. "Who knows what'll be on the market next," Handy says. "A weeping, pink, variegated dogwood?"
Valerie Easton is a Seattle freelance writer. Check out her blog at www.valeaston.com.