Camellias at Bay Laurel Nursery and within the Santa Clara Valley are now blooming, and those that bloom later will continue for a month or so. It is unfortunate that the flowers are so abundant while weather conditions are so conducive to proliferation of camellia petal blight, which is the most common disease among camellias. This fungal pathogen enjoys cool damp weather and readily infects wet camellia flowers.

Camellia flowers that have been infected with petal blight quickly turn brown and either disintegrate or fall to the ground somewhat intact but "mushy." Discoloration typically begins at the centers of the flowers and spreads outward. White and pale pink flowers are most susceptible.

There is no remedy for camellia petal blight, but sanitation may minimize continued infection. Rotting or fallen flowers and petals should be removed and disposed of where fungal spores cannot become airborne. This material can be buried or placed in trash bags, but should not be incorporated into compost.

If mulch is used around camellias, it should be replaced at least annually and should be about four inches deep to prevent spores within the soil from escaping.

Because most cultivars of camellia produce more floral buds than they can sustain, abscission of a few or many of these buds is normal. However, minimal irrigation of young plants or superfluous irrigation of any camellia may cause excessive abscission and subsequent diminishment of bloom. Occasionally, rapid and extreme decrease of humidity within a normally humid garden can also cause excessive abscission.

Camellias can be pruned in summer, but should ideally be pruned immediately after bloom.

The first new vegetative growth to emerge will be directly behind fading blooms, but growth from lower buds will be stimulated by removal of distal (tip) portions of stems.

Tree of the Week:
Norway spruce

The tallest, largest and oldest trees on the planet are native to California. Australian botanists claim to have found a Eucalyptus nicholii that is taller than the tallest coastal redwood and larger than the largest giant sequoia, but have somehow misplaced it. Banyan trees of India propagate vegetatively and perpetually from trees that grew from seeds that may have geminated thousands of years ago and possibly before the oldest bristlecone pines were born. Perhaps they learned how to do this from older and more experienced coastal redwood, creosote bush, yucca or other native Californian species.

One of the few things that are not found in California is the "most secluded tree." I doubt many Californians are disappointed that California lacks an area devoid of trees that is as vast as Antarctica, where the world's most secluded tree resides. This solitary Norway spruce, Picea abies, was planted at an Antarctic research station because it is one of the few species that is resilient to the climactic conditions that have maintained the vast desolation.

Ironically, Norway spruce is not so well adapted to the minimal humidity and warm summer weather of the Santa Clara Valley. Many older trees exhibit damage incurred during smoggier and consequently more stressful times. The "straight species" can become taller than 100 feet in a more comfortable climate but is much shorter and very rarely seen locally.

Almost all local Norway spruce are rounded and bushy dwarf cultivars that are limited to less than 4 feet tall. "Pendula" may eventually sprawl as wide as 10 feet. The most popular cultivar, "Nidiformis," which is known as the bird's nest spruce, is typically less than 2 feet tall and twice as wide. Because they are so compact, dwarf Norway spruce can live in containers for many years. Aphids may be problematic.

Horticulturist Tony Tomeo can be contacted at 408.358.2574 or at LGHORTICULTURE@aol.com.