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SAN JUAN COUNTY NOXIOUS WEED BOARD |
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Invasive Spartina Threatens Our BaysContributed photo
Jeremy Snapp and Bob Rowland remove spartina. posted 11/11/05
Spartina (Spartina anglica and other species), also known as cordgrass, is an aggressive weed that has caused serious environmental and economic damage across the Pacific Coast. In Willapa Bay in Washington state, for example, spartina has radically changed the nearshore habitat, with dire consequences for many of the area's oyster growers. Spartina control efforts in Willapa Bay have cost state taxpayers millions of dollars. Until recently, the plant was believed to be exterminated from San Juan County. But this year a state crew from the Department of Agriculture located patches at several locations in the county. In addition to the Weeks Wetland Preserve, infestations were found at Mud Bay and Spencer Spit Lagoon on Lopez, Buck Bay on Orcas, and Jakle's Lagoon on San Juan. Eradication of the plant is a top priority for the state and for the San Juan County Noxious Weed Control Board. "Spartina is a real threat to our county's intertidal lands," said Eliza Habegger, Land Steward with the San Juan County Land Bank. She noted that the natural saltmarsh at Weeks Wetland Preserve is popular with waterfowl and other wildlife, not to mention local walkers. Left unchecked, spartina has the potential to change that habitat and displace native species. " Fortunately," she said, " The local infestations are still small. If we are vigilant and don't delay, we have a good chance of eradicating this nasty weed from our island shores." The San Juan County Noxious Weed Control Board is available to help landowners identify and combat spartina. "Saltmarshes, mudflats, and estuaries are the perfect habitat for the plant" said Rich Lee of the Weed Control Board. "We're asking landowners to be on the lookout. Please contact us at 376-3499 to learn more." There are also a number of informative Web sites. Poison Hemlock in San Juan CountyBy Richard Lee, Coordinator
posted 06/23/2006 Recently I had the chance to revisit this landscape and found it drastically altered. Poison hemlock (Conium maculatum), a weed uncommonly found in the valley forty years ago, has now become, along with milk thistle, the dominant plant. Miles of roadside and acres of grazing land are now choked with hemlock six to ten feet tall, interspersed with islands of thistle. In the canyons, familiar native plants such as tiger lilies, sages, and red delphinium are now rare, largely replaced by invasive species. Rangelands that were once used for light grazing are now so devoid of nutritious grasses that year around supplemental feeding is often necessary. The slopes of the oak woodlands are left bare and exposed to the fall and winter rains because the allelopathic chemicals left by the decomposing hemlock inhibit the germination and root growth of the grasses and other plants. Poison hemlock thrives in cool, moist climates. Originally from Eurasia and introduced to North America as an ornamental garden plant, hemlock is better adapted to the climate of the San Juan Islands than it is to coastal southern California. Seeing its success there gives us cause for concern about the potential for its spread in our islands where small stands of poison hemlock have been present for years. Only recently have we started to see signs that the population is expanding. As it is a Class C noxious weed, we have, in the past, tended not to put much emphasis on its control or eradication. Small patches, especially on Lopez Island, and to a lesser extent on San Juan and Orcas, are becoming larger and more common on roadsides, in gravel pits and in other disturbed areas. Poison hemlock is a potently toxic member of the parsley family. It is easily confused with other more benign members of this family, such as Queen Anne's lace or wild chervil. It may be distinguished chiefly by its lacey, fern-like leaves, its height (up ten feet) and its smooth purple-blotched stalks. Often called "fool's parsley", only small amounts can sicken or kill both humans and livestock. Poison hemlock can also cause birth defects when consumed by pregnant livestock. In ancient Greece, hemlock was the classic executioner's potion used to assassinate Socrates. All parts of the plant are toxic, although livestock will normally avoid it, due to its characteristic "mousey" odor, unless there is nothing else to eat. Plants left in the field after cutting become more palatable, although the toxins are only slightly lessened by slow drying. While timed mowing of hemlock before seed ripening is a good control method, the cut plants should not be left on the ground as chemicals leaching from the decomposing plants (and, especially, the flower heads) suppress the regrowth of other vegetation. Other control methods include digging out individual plants before the carrot-like roots become too large and spot treatment with herbicides such as glyphhosate (e.g. Roundup®) when the plants are still in the rosette stage. Repeated cultivation in croplands can prevent hemlock from becoming established. In some areas of the northwest, the hemlock moth (Agonopterix alstroemeriana) has been used successfully to defoliate large stands, but this insect has not yet been particularly effective in the San Juan Islands. For more information on poison hemlock and other noxious weeds call or email the County Noxious Weed Control Program at 376-3499 rich@sanjuanweeds.org or judy@sanjuanweeds.org. |
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