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Missouri Environment & Garden



AUTHOR

David Trinklein
University of Missouri
Division of Plant Sciences
(573) 882-9631
trinkleind@missouri.edu

Dogwood: Nature's Little Show-off

David Trinklein
University of Missouri
(573) 882-9631
trinkleind@missouri.edu

Published: April 4, 2016

Few spring scenes are as spectacular as the annual display provided by dogwood trees in the Ozark woodlands. Inconspicuous for most of the year, these diminutive denizens of our forests outdo their towering neighbors by providing a spectacular exhibition of color before most other species leaf out. This provides for an unobstructed view of nature at its finest. The idiom "every dog has its day" could easily be applied to dogwood whose day(s) usually occur in April in our state.

The name "dogwood"; was first recorded in England in the early 16th century. Some historians believe the name was derived from the English "dagwood"; which, in turn, was a shortened version of "daggerwood."; The latter term made reference to the tree's very hard, close-grained wood which, in medieval times, was used to make daggers, arrows and other weapons. Another theory suggests the name stems from the fact that the bark of the tree, which is rich in tannin, was a key component of a solution used for curing mange in dogs.

dogwood flower

Flowering dogwood (Cornus florida) is the state tree of Missouri and has been designated as the state flower of both Virginia and North Carolina. Dogwood's true flowers are rather inconspicuous, clustered tightly together in a tiny yellow bundle in the middle of the four showy, petal-like bracts. The latter are usually white in color although pink and red cultivars do exist.

Dogwood is adapted to a wide variety of climates and soils, however, they naturally grow in moist, fertile soils high in organic matter. It is generally considered best to treat dogwood as an understory tree. This means it performs best when it receives some shade during the hottest part of the day. However, it also may be grown in full-sun exposures, given proper care. Dogwood is tolerant of cold weather, but can be damaged and does not grow well where winter temperatures frequently fall below -15 degrees F. Although dogwood is fairly tolerant of dry soils in the summer, it cannot endure poorly drained, wet sites.

In the landscape, dogwood is a ubiquitous small tree that is attractive during all seasons of the year. Many cultivars have been developed which tend to provide better flowering and adaptability to home landscapes, when compared with native types. However, many gardeners still find 'volunteer' seedlings to be quite satisfactory for the landscape.

White-flowered cultivars available from nurseries and garden centers include 'Cloud 9' which blooms heavily and starts blooming early, and 'Cherokee Princess' which has fairly large flowers. Seedlings of native trees are also available at retail outlets but are sold without cultivar name. They usually are less expensive and tend to be more variable in growth and flowering pattern than the named cultivars.

Pink dogwoods occur naturally and have been given the scientific name Cornus florida var. rubra. Named cultivars of pink dogwoods, usually with more intense color, have been selected for landscape use. One of the most popular is 'Cherokee Chief' which has deep, ruby-red bracts. 'Red Beauty®' is relatively new cultivar that produces dark, rosy-red bracts on a semi-dwarf tree. Several other cultivars lighter pink in color are commercially available.

Other dogwood cultivars have been selected for their variegated foliage. Examples include 'Cherokee Daybreak', 'Cherokee Sunset', 'Hohman's Gold' and 'Golden Nugget'. There even is a weeping form of Chinese dogwood, but it is slow-growing and rather difficult to find in commerce.

When planting dogwoods, it is suggested to plant them no deeper than they grew in the nursery, and into a soil that has been loosened 8 to 12 inches deep. This area should be equal to two to three times the diameter of the tree's soil ball or production container. Organic matter (e.g. compost or peat moss) can help create a favorable root growth environment when mixed with the soil around a new tree. However, take care not to add too much for fear of creating a micro-environment that the tree's roots will not want to leave.

As with the establishment of any newly planted tree, adequate water during the first two growing seasons is very important for survival. Water trees thoroughly once or twice a week during dry periods. However, avoid watering too frequently, since dogwood does not fare well in wet soils.

A common mistake made by many novice gardeners is to apply abundant amounts of fertilizer to a landscape tree in an attempt to accelerate growth. A newly-planted dogwood requires only about ¼ cup of a complete fertilizer fairly high in nitrogen (e.g., 12-4-8 or 16-4-8) in March and again in July. Evenly broadcast the fertilizer on the soil surface covering a radius two feet from the trunk

Dogwood anthracnose (Discula destructiva) is a relatively new, serious problem with flowering dogwoods, especially in the eastern and southeastern states. Typical symptoms include medium-large, purple-bordered leaf spots and scorched tan blotches that may enlarge to kill the entire leaf. Dogwood anthracnose currently is not a significant problem in the Midwest and should not discourage gardeners from planting dogwoods. It appears that well-tended trees in the landscape which are not under stress are unlikely to develop dogwood anthracnose. However, gardeners should be discouraged from bringing in trees from eastern forests into Missouri.

Other species of dogwoods exit which do not seem to be as susceptible to anthracnose. The afore-mentioned Chinese (or Kousa) dogwood is being used more frequently as a replacement in states where the disease is a problem. Kousa dogwood flowers about a month later than flowering dogwood and is quite showy. However, it must be watered during periods of drought in order to survive in the landscape. The cultivar 'Milky Way' seems to be one of the more desirable Kousa dogwoods for our climate.

Dogwood borer is the most common insect pest on established trees. The larvae of the borer, which gains entry through the bark, lives in the cambial area and can kill branches or entire trees. Avoiding damage to the bark with equipment such as lawn mowers or weed eaters is the best prevention borer.

April is a beautiful, colorful time of the year in Missouri. Take time this month to enjoy the spectacle that "nature's little show-off"; and other flowering trees and shrubs put on.

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REVISED: April 4, 2016