QUESTION: We are seeing many evergreen trees — Leyland cypress and others — with big sections of brown limbs. Is that due to the drought? Or is there some other problem affecting the trees?
The drought this summer plays a big part in the browning of Leyland cypress, but it’s not the whole story. Alan Windham, at UT Extension’s Soil, Pest and Plant Center says the branch dieback is the result of a one-two punch: drought and seirdium canker, a fungus that appears on branches or stems and in branch axils and causes the branch to die. “I’ve seen more damage this month than I can remember in several years,” Windham says.
I found a good description of seirdium canker at the Web site of North Carolina State University’s Plant Pathology Extension: The cankers are brown or purple sunken patches on the bark, and may be accompanied by a flow of resin. Affected branches may be scattered randomly throughout the tree; they turn a reddish-brown color, in striking contrast to the green, healthy foliage. The fungus can be spread by splashes of rainwater or water from sprinklers, or it can travel from branch to branch on unclean pruning tools.
There are no chemicals recommended to control the canker. Brown branches should be pruned and destroyed as soon as possible. Prune at least an inch below the canker, and sterilize the pruning tools between cuts by dipping them in rubbing alcohol or a solution of 1 part chlorine bleach to 9 parts water. Plants that are severely affected should be removed and destroyed. Watering by drip irrigation during drought can help prevent problems, Windham says.
Upright arborvitae are also having trouble due to the drought. Windham explains: Plants have different strategies to survive: some plants sacrifice older leaves to protect new shoots; some have waxy leaves, some plants roll their leaves or close up to prevent water vapor from escaping.
“Then you have plants like arborvitae, where it’s all or nothing. It’s as if the plant is saying, ‘We’re going for broke. Everything survives or nothing survives.’ Well, this strategy didn’t work out too well for many arborvitae I have seen.”
In this case, the only solution is to remove the dead trees and start again.
Garden events in Middle Tennessee
Aug. 21: Two meetings at Cheekwood’s Botanic Hall:
- The Perennial Plant Society meets at 6:30, beginning with refreshments and plant swap. Program begins at 7 p.m., and the speaker is Audubon naturalist Sherra Owens, presenting “Gardenening On The Wild Side With Nature’s Most Important Plant.”
- The Orchid Society of Middle Tennessee meets at 7 p.m. Michael Wenzel of the AtlanticBotanical Garden will speak on Phalaenopsis species.
Both meetings are open to the public.
Aug. 23: The Middle Tennessee Hosta Society meets at Cheekwood, 6:30 p.m., in the Potter Room. Guest speaker is landscape designer, photographer and writer Troy Marden; his topic: In a Southern Garden: Lessons from 20 Years of Gardening in the South.” To learn more about MTHS, visit www.mths-hosta.com.
Next month in Middle Tennessee
Sept. 5:WarnerParkNatureCenter hosts Hummingbird Happy Hour, 4 – 6 p.m. at the WarnerParkNatureCenter. Bird banding demonstrations and other kid-friendly activities are on the agenda. Free admission, but registration is required; call 352-6299. While you’re there, visit the NatureCenter’s vegetable, herb and flower garden. Info: http://www.nashville.gov/parks/nature/wpnc.
Sept. 15: Urban Chicken Appreciation Day at Shelby Bottoms Nature Center, 10 – 11 a.m., celebrates feathered backyard friends. Learn how to get started in backyard chicken keeping in a session led by Bonnie Bowles. Call (862-8539) or email (firstname.lastname@example.org) to register.
Sept. 22 & 23: Many rare and unusual houseplants will be available at the Tennessee Gesneriad Society’s annual Flower Show and plant sale, which will be held at Cheekwood’s Botanic Hall. The event is open to the public 9:30 a.m. – 4:30 p.m. Saturday, and 11 a.m. – 4:30 p.m. Sunday. To learn more contact Julie Mavity-Hudson at Julie.email@example.com.
Sept. 29: Herb Society of Nashville’s Herb Day at Cheekwood’s Botanic Hall: “Cooking & Gardening with Native Plants.” 9 a.m. – 4 p.m.; admission is $40 plus Cheekwood gate fee. To register: www.herbsocietynashville.org.