The beautiful — but fickle — dogwood
- By Janet Tompkins
- Oct 2
- 4 min read
Dogwoods, the blooming favorites this time of year, have been struggling during the past 25 years and there seems to be no solution in sight even as their popularity has not waned.
Cornus florida is the species reigning as the belle of forests and gardens in springtime even as their numbers decrease.
This is the native dogwood usually found in forests with moist, rich deep soils in the understory with other hardwoods. The seed, fruit, flowers, twigs and bark are valuable to wildlife. Native Americans used the root bark as a fever reducer, skin astringent, antidiarrheal agent and as a pain reliever.
At least 36 bird species eat the red fruit as well as other species of mammals like black bear and chipmunks. The foliage and twigs are also browsed by deer and rabbits. (From Louisiana Trees)
“They are the Goldilocks of the forests,” said Robbie Hutchins, LSU AgCenter forester. “Everything has to be perfect for them to thrive.”
They must have the right amount of shade, the right amount of wet and dryness and the bark is thin, affected by a freeze. Even in the best of circumstances, the lifespan could be short.
In the 15 years he has been with the LSU AgCenter, Hutchins has seen a notable decline in the area for dogwood.
The U.S. Forest Service report issued in 2012 puts it more in a scientific light: In addition to the dogwood anthracnose disease found in the Appalachian region “the decline of C. florida is ultimately a combination of numerous causal agents.”
Although dogwood anthracnose has never been officially identified in Louisiana, Dr. Rabiu Olatinwo, research pathologist, and Dr. Jaesoon Hwang, plant pathologist, with U.S. Forest Service in Pineville, say they have seen “dogwood decline.” The 2012 paper using 2005 data showed a 35.2 percent decline in Louisiana for dogwood.
“The major thing is we do not have anthracnose in Louisiana,” said Olatinwo. Droughts, freezes, fungal pathogens or other factors can trigger a sickening and slow death of the tree, he said.
“We see more diseased trees,” said Hwang.
“They are not in good shape but are in decline,” said Olantinwo. “But we cannot purport a causal agent.”
Various problems are evident in addition to the opening canopy that lets in more sun. Several fungal pathogens (such as powdery mildew) and pests have some effect. In some years there is drought and in other years there is too much rainfall or freezes. Soil composition or soil compaction could be factors.
Allen Owings, LSU horticulturist, noted the problem in a 2013 release.
“In the home landscape, we forget that dogwoods prefer shade, well-drained soil and acidic growing conditions. So we tend to plant them in full sun and ‘clayey’ soil and alkaline pH and wonder why they die or never thrive,” he wrote.
In the forest landscape, dogwood is an understory tree — it grows in the shade of other taller trees. If the canopy opens and more sunlight gets in, that can be a stressor for the dogwood. As spring arrives, there are limited blooms visible in the forest as the number of dogwood is obviously down.
Hutchins said there are many advantages to the dogwood, other than their beauty. They are prolific seed producers and they are a preferred food source for songbirds, wild turkey and gray squirrels among other creatures. So while there are always new dogwoods coming into the forest, the problems multiply as well.
Even aged management of the forests that is common today where the mature trees are removed and then replanted is probably not as idyllic for the dogwood as the uneven managed stands that were more popular decades ago, Hutchins said. Also the climate has moved from cooler-wetter periods that we saw prior to mid 1990s to a warmer-dryer cycle.
The effects from the 2022-23 drought area cumulative stressor on trees, which are particularly shallow-rooted trees, so the damage grows from year to year. One year there may be sick and diseased limbs, the next more decline until finally the tree will die.
A winter freeze can interrupt the vascular system of the tree, leading to another downfall in the health of the affected dogwood.
For homeowners with dogwood in their yards, he suggests they watch out for die-back from the drought and then to answer it with more frequent watering. He also cautions against mechanical damage from weed eaters. For new alternate plantings, he suggests other ornamentals trees like red-bud or silverbell that are hardier.
Nursery co-owner Samantha Young of DYN in Forest Hill can see the demise of the dogwood right outside her office.
“We have maybe one left (growing on the property),” she said.
DYN does not sell the traditional dogwood but it does offer the Cornus kousa variety. This 15-30 foot tree or multi-stemmed shrub is native to Japan, Korea, China and Taiwan. It has a white or pink flower but is different from the native variety.
“Most people looking for dogwood, don’t like the kousa when they see it,” she said. “But landscapers like it because it is stronger.”
The average buyer, however, still yearns for the old traditional dogwood.
“There is nothing that compares to it,” Young said.
Rocky Ray of Rayco Nursery in McNary does grow and sell the C. florida dogwood, mostly to other nurseries.
“I grow about a thousand each year and usually sell about 500-600,” he said. “I tell them as long as they keep in semi-shade they will do OK.”
Ray said the kousa variety, though, has a much better success rate.
(Janet Tompkins, former editor of Forests and People magazine, lives in Alexandria.)
