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Creating Urban Landscapes

Creating Urban Landscapes
Lawns, trees, and shrubs are parts of the whole manmade landscape

On the west side of the Oregon State campus is a shady avenue of tall, leafy oaks and elms, green grass, and flowering shrubs. This is 30th Street, a cool oasis in summer, a blaze of color in autumn, and a majestic archway year-round. Students and visitors alike are drawn to this leafy landscape, as people are drawn to urban parks around the world, to stroll under the trees, through seasons of color and textures.

Each element of 30th Street is beautiful, and hard-working. Planted at the edge of campus buildings, shade trees help cool buildings in summer and filter rainwater in winter. Ornamentals such as hebe, mock orange, and sweet box add color without demanding much irrigation. Lawns offer a soft, cool respite from nearby city streets and asphalt parking lots. Together these elements create a powerful landscape, one made entirely by man.

Alec Kowalewski

Lawns in the U.S. cover an area roughly the size of New England. OSU’s turfgrass specialist, Alec Kowalewski, wants those lawns to be durable, drought-tolerant, and beautiful. (Photo by Stephen Ward.)

Our urban landscapes are, for the most part, created by us. Our lawns have been fine-tuned from native grasslands; the ornamental trees and shrubs have been selected to be as hearty as they are beautiful. It’s one giant, man-made ecosystem, from the soil to the insects to the immediate climate surrounding us.

Much of these manufactured landscapes is dedicated to lawns—over 49,000 square miles nationwide, according to Alec Kowalewski, a turfgrass specialist in OSU’s department of horticulture. During recent droughts, lawns have been vilified as water wasters, which has led some homeowners to spray-paint their lawns green instead of irrigating. Kowalewski says that it’s possible to maintain a healthy lawn with minimal irrigation, and doing so offers many benefits.

“Turf’s like a sponge on top of the ground,” Kowalewski explains. “It forces water down into the soil, water that would otherwise be lost to runoff.” In the dog days of summer, he says, turf can be 30 degrees cooler than bare soil or pavement. Most lawns are a mixture of different grass species—tall and fine fescue, ryegrass, bluegrass—each contributing special attributes to the turf mix. Kowalewski is testing the viability of newer varieties that require less fertilizer and water, to create even more resilient turf for the Pacific Northwest.

Oregon Snowflake plant

Ryan Contreras, an ornamental plant breeder at OSU, is developing beautiful new varieties of landscape plants, including this compact flowering currant, Oregon Snowflake. (Photo by Stephen Ward.)

Like lawns, shrub borders are mixtures of ornamental plants that add more than beauty to the manmade landscape. Rhododendrons, azaleas, and other woody plants can provide insulation, reduce heating bills, and increase property values. Ryan Contreras, OSU’s ornamental plant breeder, is developing new plant varieties to serve many functions. Using traditional breeding methods, Contreras is selecting for traits that, for example, increase drought tolerance or cold hardiness; or plants that fit in small urban spaces and limit out-of-control spreading. Contreras’s research program has just released a low-growing flowering currant, ‘Oregon Snowflake’, that is perfect for small city yards. He’s also developing a hard-working contoneaster that will retain a natural, flowing shape in the toughest places—parking lots, curb strips, and wherever density is required and irrigation is scarce.

Amy Jo Detweiler

OSU Extension horticulturist Amy Jo Detweiler helps gardeners in central Oregon face down wildfire, frosts, and drought. (Photo by Lynn Ketchum.)

In central Oregon, the beauty of high- desert landscapes is matched by a need to be fire resistant. OSU Extension horticulturalist Amy Jo Detweiler is quick to say that there is no such thing as a fireproof plant. “Even fire-resistant plants will burn fast if they’re not maintained,” she says. Irrigating, clearing dead brush, and keeping an eye on density and spacing are among the important things homeowners can do to create a fire-resistant, defensible landscape.

Choosing fire-resistant plants is also key. Detweiler recommends steering clear of plants with dry, crumbly leaves and plants with strong scents and increased oils or resins. In addition to fire resistance, high-desert landscapes must be able to withstand extended summer drought, 40-degree fluctuations from day to night, and a chance of frost at almost any time of year. Luckily, Detweiler publishes the High Desert Gardening newsletter to help central Oregon homeowners develop beautiful landscapes that are fire-resistant and adaptable to cold and drought.

To encourage the nursery industry to embrace new, drought-hardy plant varieties, OSU horticulturalist Neil Bell is evaluating overlooked and underappreciated landscape plants at OSU’s North Willamette Research and Extension Center. Bell is currently testing cultivars of Grevillea (an evergreen shrub with odd, petal-less flowers) and manzanita (a smooth-bark shrub with bell-shaped flowers) that perform beautifully with minimal fertilizer and water.

Choosing the right mix of plants is just the beginning of creating a healthy urban landscape. Choosing the right mix of strategies to control insects, weeds, and diseases is also important. Integrated pest management is an approach that combines one discipline—say, entomology—with many other disciplines, to battle pests strategically using a broad understanding of the landscape.

Intelligent pesticide sprayer

This Intelligent Sprayer, demonstrated at Hans Nelson Nursery in Boring, Oregon, uses lasers and an on-board computer to precisely control where and how much pesticide to spray. (Photo by Stephen Ward.)

Enter the Intelligent Sprayer. A marriage between engineering and plant sciences, the Intelligent Sprayer is new technology that surgically focuses on insects and diseases to reduce the volume of pesticides applied to crops.

“The Intelligent Sprayer shows the huge impact of interdisciplinary work,” says Robin Rosetta, an OSU Extension entomologist, as she demonstrates how the new sprayer adjusts pesticide applications according to precise plant location or crop size. The sprayer’s nozzles look like robot arms topped with flexible fingers that seem to sputter as the sprayer travels down the row. The sputter comes from sensors telling the machine whether or not to apply pesticide. “Sensors detect the presence of a plant,” she says. “It doesn’t spray empty spaces.”

Rosetta is involved in a national project to test Intelligent Sprayers in nurseries. Their research has shown that the sprayer is equally or more effective at controlling pests while using up to 60 percent less pesticide than traditional methods. This, she says, could have a positive impact on air and water quality, as well as improved profits for growers and increased safety for their workers.

Creating sustainable urban landscapes requires work from many disciplines to keep soil, plants, microbes, people, and environments working together. In all these ways, landscape experts at OSU are improving the walk down 30th Street, and across the state of Oregon.