Wednesday, March 11, 2015

Tree of the Season: Incense Cedar

The incense-cedar graces many Bay Area gardens with its shade, beauty, and intriguing fragrance. Calocedrus decurrens, its Latin name, means beautiful cedar. The striking contrast between the vibrant greens of its leaves and the trunk’s rich reds creates a pleasing aesthetic further enhanced by the relaxed elegance of the weeping foliage. The beauty of this tree is not confined to the realm of the visual. The incense-cedar gives off a distinctive fragrance that fills the air with a pungent aroma strongly reminiscent of grade-school classrooms and the unforgettable smell of the pencil sharpener. In my youth, and still largely today, pencils were made from the soft, and distinctively fragrant wood of Calocedrus decurrens. 

The incense-cedar is not a true cedar (thus the hyphen). The so-called “true cedars” are native to the Mediterranean and the Himalayas, and are members of the genus Cedrus. These include the majestic Deodora and Atlas cedars, as well as the famous Cedar of Lebanon.

The incense-cedar, which may live a thousand years and attain a height of 150 feet, is a true California native. It evolved in North America, and its current range extends from the Cascade Mountains in northern Oregon, through the Sierra Nevadas, down to the Sierra San Pedro Matir of Baja California. Throughout its range it has been important in the lives of Native Americans.  The Klamath tribe of Oregon wove its bark into baskets. The California Paiutes made infusions of its leaves for colds. The Round Valley tribe of Mendocino Country used leaflets as flavoring when leaching acorn meal. This species has provided Native Americans with food, shelter, clothing and music.  

The incense-cedar’s natural resistance to rot made it very useful both in antiquity and in modern times. Homebuilders use it for siding, decking, moulding, and interior paneling. Landscapers use its chips and bark for mulch. Its wood is made into furniture, shingles, and railway ties. Sawdust and wood scraps help fuel co-generation of electricity.

The softness of the wood and its resistance to splintering make the incense-cedar ideal for encasing pencil lead. However, these qualities also make the wood fragile and brittle, and potentially somewhat problematic as an urban landscape tree. When it grows as one trunk from a thick base to a single pyramid-shaped crown, the incense-cedar is relatively stable; it requires little work other than the periodic removal of deadwood. But if the trunk of the tree divides into multiple columns, or has large branches which turn up and rise parallel to the trunk, the tree has structural problems that make it vulnerable to column failure. After some recent winter storms, Brende & Lamb looked at many incense-cedars that had shed branches and sometimes entire columns. Most of the failed trees suffered from a malady of tree anatomy called included bark. This structural defect occurs when the bark at the crotch folds inward, and interrupts the continuity of the fibers supporting the columns.

Good pruning can ameliorate many structural problems. Co-dominant stems (more than one column of roughly the same diameter) are more likely to fail than trees with a single leading column. Sometimes reducing one of the competing leaders can minimize the hazard. If column removal is not advisable for aesthetic or functional reasons, it is often possible to cable the multiple stems together. However, individual trees are so unstable that removal is the safest alternative. Whatever you do, do not top these trees. Topping a cedar will eventually produce many unstable columns multiplying the risk and, ultimately, the expense of keeping the tree. Preventative medicine is almost always less expensive and more effective than later surgery. If you plant an incense-cedar, choose nursery stock with only one trunk and no crotches with included bark. Remember that a seedling cedar can grow to over a hundred feet and that tall trees may cause view concerns for yourself and your neighbors.

Calocedrus has graced the California landscape for almost 200 million years. With a little forethought and good pruning, it can continue to bless Bay Area gardens with the subtle fragrance of childhood. It takes a little effort to live at peace with this large California native, but its bounty of colors, shapes, and scents make that effort worthwhile.

If your trees and shrubs need a little TLC - call us to schedule a free estimate.

Blaine Brende & Joe Lamb
510-486-TREE (8733)

Monday, March 9, 2015

Tree of the Season: Japanese maple

Japanese maples have an elegance and sculptural quality that resembles dance. Careful study of their form, in any season, can call the viewer back to the natural world. In winter, the falling leaves raise the curtain on the form of the trunks, and put the dance on center stage. Winter rain intensifies the show by adding a sensuality to the movement of stem and bough, one that beckons to even the unpracticed eye. In spring, certain varieties of Japanese maples send out new leaves so bright a green they appear lit from within. In summer, upright cultivars that are well pruned have spaces between the branches, giving the canopy the appearance of being composed of many floating islands. And in fall, Japanese maples mark the change of season by turning colors ranging from yellow to scarlet, depending on the variety of maple; there are many varieties. 

Luckily, Japanese maples are relatively easy to grow, and relatively tough. In their long evolutionary dance–fossilized maple leaves date back over 60 million years–Japanese maples have developed the genetic information necessary to protect them against most common garden afflictions. They are, however, subject to verticillium wilt, a soil-borne fungal disease that can cause dieback, and sometimes death. There is no known cure for verticillium, but you can decrease the likelihood of your new maple getting the disease if you 1) don’t plant it in ground known to have verticillium, 2) make sure the soil around the tree is well drained so that the roots don’t remain soggy throughout the winter, and 3) protect the tree against environmental stresses by giving it summer water and keeping it well mulched. Maples can grow and remain healthy in gardens with a history of verticillium. If they are not stressed by soils too damp, too dry, or too compacted, some individual maples can thrive even though a near neighbor may die. It depends on the genetics of the individual. If your mature maple shows significant dieback, it may be fighting a case of verticillium. It is not necessarily a death sentence. Some trees succeed in fighting off the disease. You can help them recover by pruning out the deadwood and improving the soil environment by mulching and aerating.

Though some varieties can withstand full sun, Japanese maples do best in part shade. They do not thrive when exposed to the drying effect of constant wind. If you live on an exposed hillside, it is best to plant them in the lee of a larger tree. Dieback in Japanese maple crowns often is the result of too much sun, too much wind, or the even more deadly combination of the two. Maples need water. Keeping them moist throughout the summer and fall, and into the early winter in dry years, will make them happier and more disease resistant.

Pruning, besides benefiting the mental health of the pruner, can enhance the grace of the plant. If your pruner is an artist, removing deadwood and teasing apart the plant’s natural layering opens little windows that reveal and accentuate the tree’s natural form. A well-pruned tree looks as if it hasn’t been pruned. Paradoxically, it looks more natural after pruning than before. Though it is sometimes necessary to lower the crown of a maple, as when it is beginning to block a treasured view, lowering should be done only when necessary, and the lowering should not be so drastic as to involve topping cuts (see the article on topping). Lowering a maple to gain a view is not something that you can do just once. Pruning down the crown stimulates new growth, and maintaining the view, or the size reduction, will require yearly pruning. No matter how good the artist, you can’t make a topped maple look as good as a natural tree. Much pruning, and therefore expense, can be avoided by planting the right variety in the right place. When planting a new tree, plant a cultivar that won’t exceed the desired height when it matures. This is almost always preferable to containing a variety that will grow beyond the desired size.

It is our hope at Brende & Lamb that the pleasure our clients derive from their well-pruned trees exceeds the considerable pleasure we get from revealing the beauty inherent in their trees.

If your trees and shrubs need a little TLC - call us to schedule a free estimate.

Blaine Brende & Joe Lamb
510-486-TREE (8733)