By Scott Aker
Special to The Washington Post
Thursday, July 9, 2009
Q: I admire the tall and slender Italian cypress, though when I found one for sale recently it was a dull bluish color with ugly leaves. I wonder whether there are other evergreen trees with the same desired shape. Also, when I was in Vancouver, B.C., I saw evergreen trees whose foliage was almost fanlike. I wonder what they are and whether I can use them in Northern Virginia.
A: I'm not sure what you saw in Vancouver. It could have been a Port Orford cedar, and, unfortunately, they do not do well in our hot summers.
It sounds as though you are looking for an evergreen conifer with bright green foliage that is very narrow and upright. An Italian cypress would fit that bill, but it is not hardy here. Common juniper is hardy, and Hibernica is narrow and upright. California incense-cedar would be another good choice, with its wonderfully fragrant foliage. You might try Red Star (also known as Rubicon) Atlantic white cedar. It develops a purple-red hue in winter and nice, soft foliage if you don't like the needle-sharp foliage of the common juniper.
Is it necessary to rake or blow the fall leaves that drop on our ivy beds? Our trees are oak and cherry.
Considering ivy's invasive nature in our woodlands, I can tell you that it is unnecessary to rake leaves off your ground cover. Even more-desirable ground covers can be left unraked, unless the leaves are unusually deep. These plants are naturally adapted to woodlands and cope nicely with an autumn blanket of leaves, which they are able to grow through in spring.
When I prune my Viburnum carlesii, a fine, gritty dustlike substance filters out of the leaves, covers my arms and gets in my eyes. What is this material, and does it serve some botanical purpose?
The gritty dust may be the remnants of a scale infestation, possibly of a species called the lintneri scurfy scale. This insect is also seen on dogwoods and lilacs.
Although they reproduce rapidly, they do little damage because they are so small. They are usually present briefly before predatory insects consume them. The fact that the scale covers are loose indicates that they are from an infestation that has run its course.
Scott Aker is a horticulturist at the U.S. National Arboretum.