Beetle infestation prompts tree removal

An arborist lowers a section of a dead tree in Duke Gardens.

By Sheon Wilson

Publications Coordinator

Crews are removing three pine trees in Duke Gardens' Culberson Asiatic Arboretum this week after detecting a virulent pest: the Southern pine beetle. 

The beetles have attacked two mature pines in Pine Clouds Mountain Stream, so arborists are removing the trees before the scourge spreads. A third vulnerable tree nearby will also be removed.

Southern pine beetle.
Photo by Marc DiGirolomo,
U.S. Forest Service

Visitors will be unable to walk through the Pine Clouds area during this work. They will be redirected with detour signs. We apologize for the inconvenience.

The work should take about three days; we will update here when it's finished. It requires taking down the trees one section at the time to avoid damaging the plants beneath. 

Southern pine beetles bore tiny holes
 into unhealthy pine trees.

During the two-year construction of the Japanese garden, which was completed in 2016, the weight of heavy equipment damaged some roots. That weakened the trees and prompted the beetles to move in. They bored tiny holes and ravaged the trees from the inside.

 “We noticed that the tops of the trees were brown; that appeared over a weekend,” said Bobby Mottern, director of horticulture. “Pine beetles are notorious for detecting trees that have been weakened.”

When pine trees are infested with Southern pine beetles,
as is the tree in the forefront, they look brown and weak.

Southern pine beetles are common, native insects. They know when a tree is stressed - by compacted soil or even drought, for instance - because the tree sends out a pheromone that the beetle detects. 

Once that happens, it’s hard to stop the beetles’ damage without fully removing the tree. Keeping trees healthy is about the only way to prevent infestations.

All photos by Sheon Wilson, except where noted.

Class Preview: Make Your Garden Sing

Add "music" to your garden with ornamental grasses.
Photo by Bob Ayers.

By Rose James T'20

Plants whisper, seed pods clack and the wind rustles through leaves outside your door. A bird trills and a frog croaks, perhaps bringing you back to childhood games of hide and seek in your favorite neighborhood garden. A nearby brook bubbling might bring you back to a pleasant afternoon catching toads with your cousins or fishing with your grandfather.

Plants that attract birds will make your garden sing.
Photo by Charles Twine.

Our sense of sound is one of the strongest triggers for memories. A sound can bring to mind a person or place that you loved, or a favorite pastime. Sometimes this can be a happy accident. But like a composer, you can also shape your own environmental symphony to spark joyful memories or create new ones.

Whether your garden spans many acres or a small bed, consider adding sound to your design principles of form, function and color. Hilary Nichols can help you weave those sounds in a new two-session class at Duke Gardens, “I Need a Plan: The Musical Garden.”

Nichols is garden manager at the Durham nonprofit SEEDS, an urban sanctuary focused on promoting the principles and practice of sustainable agriculture, organic gardening, food security and environmental stewardship. She strives to live her life intentionally, and she loves sharing her design and horticultural expertise to help gardeners at all ability levels create gardens that sing to ears and eyes alike.

Streams and rain gardens are perfect to add a croaking frog
or two to your chorus. Photo by Sue Lannon.

The plants you choose, and the way you arrange your plants, will influence the musicality of your garden, Nichols says. Enjoy the wind strumming the blades of ornamental grasses or rattling autumn leaves. Place a large-leafed plant near your favorite window to enjoy the rain pattering on the leaves. Select plants that attract insects or birds to add a percussive buzz and lilting song. Study the life-cycle of your plants to create a garden in bloom throughout the year, drawing animals to your garden in different seasons.

Sign up for “The Musical Garden” and Nichols will have your garden singing in no time.

“I Need a Plan: The Musical Garden” meets on two Tuesdays, Oct. 11 and 18, from 6:30-9 p.m. To register, or for more information, please call 919-668-1707 or email gardenseducation@duke.edu.

Blogger Rose James is a Duke freshman and work-study marketing assistant at Duke Gardens. 

Vegetable Gardening Tips

Summer campers helped tend a
vegetable garden at Duke Gardens.
Let Duke Gardens help you grow
your own bountiful garden.

By Kate Blakely

Gardening tips always take on the perspective of the gardener. What the gardener cares about intimately shapes the information he or she is sharing. Vegetable gardening is no different. Amidst all the wonderful info about growing veggies, it’s the intent that makes each tip unique and special.

Vegetable gardener Andy Currin has lots of tips to share. Currin will teach a Spring Vegetable Gardening class that begins Thursday, March 22, from 6:30-8:30 p.m. and runs for three weeks. It’s part of Duke Gardens’ Vegetable Gardening through the Year series. Currin shared some tips for how to grow vegetables in a healthy, sustainable way.

Watch when you water. “Of all points of sustainability, the main component is efficient water use,” Currin said. A lot of folks will water their gardens, their lawns and their flowers during the heat of the day, when the sun is working hardest. “You lose more water to evaporation than will actually get to the plants to be useful to them,” said Currin. The best planet-friendly practice is to water in the early morning or after the sun starts going down.

If you want to eat organic, start organically. If you want to grow organic vegetables, you must be vigilant about everything involved, from soil to seeds. “Some of the seeds, if they’re not labeled as organic, could contain seed treatments that would be systemic,” Currin noted. This means that chemical compounds in the seeds will be found throughout the plant. “And that would be included in the vegetables that you’ll be eating. You really have to start with the seed, any soil amendments, anything like that. Everything has to be organic approved.”

Watch (and help) the right bugs. Pollinators and predatory insects are the most beneficial. Currin has a “good list” and “bad list” of insects. At the top of the good list? Hoverflies. They are both a pollinator and a predatory insect, Currin said. Native bees also help out. The orchard mason bee, the bumblebee and the leaf cutter bee work to pollinate plants. Praying mantis, ladybugs and green lacewings also help. “They eat the bad guys,” said Currin. The bad guys? Aphids, thrips and squash bugs.

As part of your organic practices, make sure to complete any pest treatments around dusk, when the beneficial insects are not going to be out and about. That makes the least impact on the beneficial insect population. “Even organic treatments don’t really discriminate; they just take out everything,” Currin said.

Learn more: Want to know more? Consider taking Currin’s vegetable gardening classes at Duke Gardens. The class costs $75; $60 for Gardens members. If you can’t take the spring class (or in addition to it), consider the fall series, which runs from Sept. 20 to Oct. 4, also from 6:30-8:30 p.m. Please call 919-668-1707 to register. Please see our website for more information about classes and other public events at Duke Gardens.

Sarah P. Duke Gardens creates and nurtures an environment in the heart of Duke University for learning, inspiration and enjoyment through excellence in horticulture. The Gardens is at 420 Anderson St.

Kate Blakely is a graduate student at Duke Divinity School and a work-study assistant at Duke Gardens.