Dirty camellia leaves? It's probably 'sooty mold'
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Q: My camellia leaves look dirty, with a dark messy covering over the green. Any ideas?
A: Your camellia's probably covered with a fungal disease aptly called "sooty mold." The problem doesn't usually harm the plants, though it certainly looks unappealing. Sometimes, a large, old camellia appears blackened as if by smoke.
Sooty mold is caused when sucking insects attack the plant and excrete a sugary "honeydew," which falls onto leaf surfaces. The fungus grows in the honeydew, turning it black. (To see illustrations of this and confirm the diagnosis, check on the Web site for Washington State University Hortsense: pep.wsu.edu/hortsense ).
Check the plant for insect infestation. WSU recommends washing the leaves with a strong spray of water to remove the honeydew (before it's infected by the sooty mold). A thick coating of sooty mold may have to be hand-scrubbed (a soft brush works well). The fungus doesn't penetrate the leaf surface, so the leaf cleans off without residual internal damage. No fungicides are suggested for sooty mold, though a heavy infestation of aphids or scale can be treated by insecticidal soap.
If the plant occupies a prominent garden spot, cleaning it may make sense. For huge old plants soaring 20 feet into the air in shaded back gardens, coexistence with the sooty mold may be more appealing.
Having discussed a common camellia problem, I'm now inspired to cheer for these adaptable garden reliables. Camellias give Western Washington landscapes an exotic, Southern appeal and deserve greater appreciation and use. They offer year-round leaf beauty, with distinctly pointed shining green foliage. Once settled in the garden, after about 3 years of life, they handle summer drought well without requiring extra irrigation.
An established camellia is a fine "backbone" plant, with the bonus of elegant flowers from January through March and even into April. Flower arrangers appreciate the shapes and colors, from whites through deep rose.
Hybrid camellias enjoyed great garden popularity from the 1940s onward. Their distinctive character defines some landscapes in Southern California and the deep South. Large plants in Western Washington probably entered gardens in the 1950s when they were commonly planted as foundation shrubs (though they are unsuited for planting in front of windows, as many can easily exceed 20 feet in height when mature).
With more than 3,000 hybrids in cultivation, gardeners have ample choices for garden use. One of the loveliest of camellias, the hybrid 'Donation,' rightfully appears on this year's list of "2002 Great Plant Picks" for Western Washington. (The Web site for all the "Great Plant Picks" is www.greatplantpicks.org.)
A soft, agreeable pink, 'Donation' combines well with early white daffodils and later blue forget-me-nots. 'Donation' descends from Camellia x williamsii, and shares the trait of its parents in dropping flowers nicely off the bush once they've faded. The plant thus keeps a tidy appearance (unlike many relatives of Camellia japonica where old flowers dangle unless hand-pruned.)
Visit nurseries now to see and select camellias, because the long, cool spring we've had has allowed camellias to hold their blooms later than usual.
Camellias require well-drained soil and protection from direct, hot sun. Our mild winters and extended springs suit them perfectly. Many will bloom in light shade under limbed-up deciduous trees if the soil conditions include lots of organic amendments. They need cold protection and won't live through extremely severe winters. My mother, a Southern California native with a fancy for camellias, grew them in a heated greenhouse in Ohio. She invited the neighbors for coffee to celebrate one bloom at a time as the pampered plants defied winter and offered up 'Pink Perfection' and 'Debutante.'
Whether you love camellias for their family associations, or for their terrific water-wise landscape qualities, they're worth adding to the garden this spring.
Mary Robson is area horticulture agent for Washington State University/King County Cooperative Extension.