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Gardening Answers Knowledgebase

Plant Answer Line Question

Keywords: Pruning shrubs, Cotinus coggygria, Cornaceae (Dogwood family), Trees--Diseases and pests

Can you give me some general information about Dogwoods and anthracnose? Also, I would like to know about coppicing Cotinus coggygria.


Here is information about dogwoods and anthracnose:
The U.S. Forest Service article entitled How to Identify and Control Dogwood Anthracnose, may be of use. Although it is somewhat technical in its language, there are excellent pictures and a section about methods of control.
Master Garden Products.com provides a short article about Dogwood Anthracnose that contains a What to Do list.
Oregon State University Extension's Online Guide to Plant Disease Control provides a corroborating list of cultural controls for Anthracnose and adds an extensive list of chemical controls. It's always best to use cultural controls and avoid chemical ones if you can. Some dogwoods in the Pacific Northwest have been known to recover from anthracnose, according to Douglas Justice of University of British Columbia Botanical Garden.

The Royal Horticultural Society has useful general information on coppicing, and includes Cotinus coggygria among those plants which respond well to this pruning technique.

Date 2016-12-22
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Plant Answer Line Question

Keywords: Cotinus obovatus, Cotinus coggygria, Fall foliage

I planted some beautiful Cotinus coggygria 'Grace' in practically full southern exposure in my yard, and their foliage has gradually turned from deep wine red to a pale olive green. Is my soil not acidic enough? Did I overwater? Or is it something else?


You are not alone in noticing this color change. I found the following discussion about Cotinus coggygria x Cotinus obovatus 'Grace' on a GardenWeb forum. Here is an excerpt:
"The true 'Royal Purple' smoke bush will not turn green. Some smoke bushes are grafted, most do not grow true from seed. You must order one from a true nursery or visit a specialty nursery to get a good Royal purple smoke bush. There are also many different purple smoke bushes who have different characteristics. 'Grace' is a hybrid cross between the green smoke bush and Velvet cloak (which is a gorgeous true purple smoke bush). 'Grace' has blue green leaves with red tinges around the leaves."

An article by David Wheeler in the British paper The Telegraph describes this variety of Cotinus:
"A hardy plant of exceptional beauty at several different times of the year, Cotinus 'Grace' has nothing of the leaden darkness so often criticised by those who dislike purple foliage. Less purple than red suffused with green, the leaves bring a bold note to the garden that can complement or offset other foliage colours.
'Grace' is a garden hybrid, one of five seedlings resulting from a deliberate cross between the American chittamwood (Cotinus obovatus) and a variety of the Venetian sumac (C. coggygria 'Velvet Cloak'). Raised by Peter Dummer, propagator at Hillier's nursery, in Winchester, in the late 1970s and named after his wife, it has won the Royal Horticultural Society's top awards. Like both parent plants, it exhibits long-lasting autumn colour, the prominently veined, broad oval leaves (up to 5in long) turning to a brilliant scarlet before falling in mid-October."

A page from Woodlanders Nursery catalog suggests the green phase is normal:
"Reddish new foliage turns blue-green and finally good orange, red, and yellow in fall. Plant in a sunny location with well-drained soil."

The Brenton Arboretum in Dallas Center, Iowa describes the leaf color change similarly:
'Grace' - Hybrid between C. coggygria and C. obovatus; large pink panicles; leaves 4 to 6" long, light red when young,turning blue-green in summer and red, orange or yellow in autumn; height estimated 20'; zone 5.

It sounds to me as if the leaves go through several changes, and your patience will probably be rewarded with the expected fall color in time.

Date 2017-08-15
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August 01 2017 12:36:01