Dawn Redwood Diseases
The dawn redwood (Metasequoia glyptostroboides) is an ancient tree that existed more than 65 million years ago. Native to China, botanists long thought this tree extinct until it was rediscovered in the 1940s. Dawn redwoods typically winter well in U.S. Department of Agriculture plant hardiness zones 4 or 5 through 8. Valued for their hardiness, dawn redwood trees are resistant to most pests and plant diseases, with canker infections being the most serious exception.
Dawn Redwood Description
The dawn redwood is a massive tree that reaches up to 65 feet in height with spreads ranging between 15 and 25 feet. It is often used as a specimen tree or for shading purposes in large landscape areas. Although it looks like an evergreen tree, the feathery, needlelike foliage is actually deciduous and often turns vibrant reddish-bronze colors in the autumn. These trees bear small, brown cones and have a distinct reddish-brown trunk.
Potential Disease Problems
Dawn redwood trees are resistant to most serious plant diseases, including Verticillium wilt and oak root fungus, but occasionally suffer from canker infections. Caused by several different fungal pathogens, this disease causes flat, sunken areas of dead tissue to form on infected wood tissue. Affected branches typically bear yellow, brown or wilted foliage and infected bark often seeps a discolored resin. Affected trees sometimes experience twig, branch or top dieback. During wet weather, the fungal fruiting bodies grow in dead wood tissue and spread through splashing water and wind.
Unfortunately, no chemical controls exist to treat redwood cankers, as of March 2013. Cal Poly suggests pruning out any canker infected, dying or dead branches as soon as you notice them. Cut into the healthy wood below the canker and as close to the trunk as possible, making sure that you don't leave any stubs where canker pathogens can enter the wood tissue again. Destroy all pruning debris immediately to prevent spreading canker disease to other redwoods growing nearby.
Dawn Redwood Tree Care
Giving your dawn redwood tree the proper care keeps it healthy and reduces its chances of contracting canker disease. These redwoods prefer fully sunny to partially shady sites with acidic to slightly alkaline soils. Plant your tree in loamy, sandy or clay soils with good drainage for the best results. These trees don't tolerate compacted, saturated or poorly draining soils, but thrive in consistently moist soils. Adding a layer of organic mulch beneath your dawn redwood tree's canopy can help retain consistent soil moisture.