Bryonia alba
(white bryony, wild hops, devil's turnip)
on the Palouse

Compiled by David Hall
Palouse Prairie Foundation
July 2004

Bryonia alba. Photo by G. O'Keefe
Photo by G. O'Keefe

White bryony (Bryonia alba) is spreading so fast, and has such severe consequences on wildlife habitat and tree plantings, that it has been listed as a noxious weed in Latah County, Idaho. An introduction to North America from Europe, it has been in the Inland Empire area of the Pacific Northwest since the 1970s, and was first reported in Latah and Nez Perce counties in 1984.

White bryony thrives in full sun--it is one of the first plants on the Palouse to show frost injury-and it often grows on the sides and tops of trees and shrubs, effectively excluding light to the leaves of and thereby weakening the enshrouded plant. In the winter, the bryony stems and leaves capture and accumulate snow, which can lead to damage of the supporting plant, breaking its limbs and stems, leaving open wounds vulnerable to invasion by disease and insect pests.
Douglas hawthorn being killed by Bryonia alba. Photo by G. O'Keefe
Douglas hawthorn being killed by Bryonia alba.
Photo by G. O'Keefe. 		Bryonia alba on a dead Douglas hawthorn. Photo by Trish Heekin
Bryonia alba on a dead Douglas hawthorn.
Photo by Trish Heekin.
White bryony is prevalent in native hawthorn patches and in windbreak, shelterbelt, riparian buffer, and wildlife plantings. Many of the trees and shrubs planted under these practices are selected specifically to be attractive to wildlife. With these plants overtaken by white bryony, one can expect a decrease in wildlife nesting, roosting, travel and hiding cover, berry food sources, and protection from severe winter winds and storms. The wind protection for buildings, crops, and livestock, and the supporting plants' possible attractive, aromatic spring blossoms and striking colorful fall foliage also can be lost.

Description

White bryony is a vine that will grow as much as 6 inches a day to a length of 60 to 150 feet. It has dark green, shiny leaves that resemble those of a cucumber plant--simple, up to 5" long, palmately five-lobed and petiolate, rough to the touch. A single, unbranched tendril is associated with each leaf. Its yellowish white flowers, borne in small panicles, yield small green berries that turn dark purple in late summer. Robins and other songbirds readily eat the ripe berries and disseminate the seed.
Bryonia alba leaves. Photo by Gary O'Keefe
Bryonia alba leaves.
Photo by Gary O'Keefe. 		Bryonia alba stem and tendril. Photo by Gary O'Keefe
Bryonia alba stem and tendril.
Photo by Gary O'Keefe.

Bryonia alba flowers. Photo by Gary O'Keefe
Bryonia alba flowers.
Photo by Gary O'Keefe. 		Bryonia alba leaf and berries. Photo by Gary O'Keefe
Bryonia alba leaf and berries.
Photo by Gary O'Keefe.
The root, which resembles a large white turnip, may be as large as 6" across, 18" long, and may weigh up to five pounds. These large roots effectively fuel spring re-growth. Like wild cucumber, white bryony spreads by seed, not by fragments of the root.
Bryonia root. Photo courtesy of PCEI.org Bryonia alba found popping up through the new stream restoration site at the South Fork of the Palouse River along Palouse River Drive just south of Moscow on April 17, 2004. It resembled a cow parsnip in its young stage at first glance (similar color and size), but obviously different with the hairy stems and leaves, multiple stems, tendrils, etc. Root segment is nine inches long, four inches in diameter at its widest point and weighs 1 lb 2 ounces.
Photo courtesy of Palouse-Clearwater Environmental Institute.
White bryony is poisonous, causing illness and death in man and livestock. Fruits are emetic to humans; forty berries are fatal to an adult human.

Control

To be safe, wear protective gear when handling this poisonous plant.

The use of broadleaf herbicides on white bryony is not recommended if the vine is covering a deciduous, broad-leaf species unless the bryony plant is pulled away from the supporting plant canopy before application. To be effective, the herbicide must move to the root and block production of new shoots.

Control of bryony through tillage is also problematic; bryony typically grows close to the base of the supporting plant and tillage would harm the desirable plant's roots.

Severing the bryony vines is ineffective because the bryony plant grows back from the root.

The most effective method for control is damage to the root. Finding the root during the growing season can be difficult. It is easiest to wait until autumn, after the leaves have died, to locate the roots. Then sever the roots 3 to 4 inches below the surface with a #2 shovel. This removes the crown and prevents re-sprouting.

Be sure to walk your shrub and tree stands each year, scouting for any escapees from the previous year and for new white bryony plants. Cut and remove new growth immediately and repeatedly throughout the growing season, and return in the autumn to locate and sever the roots of the new plants.

The Pullman, Washington, USDA Plant Materials Center technical staff are investigating effective methods for control of white bryony. As reports on control attempts of this harmful vine become available, local Natural Resources Conservation Service staff will make them available to the public.

Sources

Stannard, M. Revised by T. Heekin. June 2002. White Bryony: "The Pacific Northwest Kudzu." U.S. Department of Agriculture, Natural Resources Conservation Service, Pullman, WA and Moscow, ID. 4 p.

Miller, T.W. February 1995. Two wild vine plants in Idaho: one a weed, one not. Weed Watcher 2(2). University of Idaho, College of Agriculture, Weed Diagnostic Laboratory. 2 p.

O'Keefe, G. n.d. Control of white bryony (Bryonia alba). Latah County Noxious Weed Control, Moscow, ID. 1 p.

O'Keefe, G. n.d. White bryony (Bryonia alba, Cucurbitaceae -- cucumber family) listed noxious weed, Latah County, Idaho. Latah County Noxious Weed Control, Moscow, ID. 1 p.

Photos by Gary O'Keefe used by permission of Gary and of the Latah County Weed Control Department.
All sources currently are available from the Natural Resources Conservation Service offices, Federal Building Second Floor, Moscow, ID.

-----
Palouse Prairie Foundation, P.O. Box 8952, Moscow, ID 83843
palouseprairie.org