CARLSBAD–Carlsbad City Council approved Tuesday a program to eradicate invasive plant, Ward’s weed from the city’s protected natural environments and open space.
Ward’s weed has spread to approximately 200 acres of habitat and it threatens the city’s native plants, wildlife and agricultural areas. It can grow as a thick mat that chokes out all other native plant species, according to the City of Carlsbad.
“Due to the extremely high seed count of up to 30,000 seeds per plant per year, this species can spread quickly, and presents a fire hazard in our open spaces and canyons. It is considered a flashy fuel which means that it could ignite easily and burn quickly,” said Rosanne Humphrey, the city’s senior environmental program manager,
Ward’s weed is not native to Carlsbad. How it arrived in the city is unknown.
The City Council approved up to $200,000 in funding to add to the $200,000 in grant funding obtained by the Nature Collective, San Diego County and Center for Natural Lands Management for a total of $400,000 over the two-year program. The sources of grant funds include SANDAG and California Wildlife Conservation Board.
The aggressive treatment strategy consists of spraying a pre-emergent herbicide that suppresses seed germination, approximately one or two weeks before measurable rain arrives in November or December. This does not harm most woody shrubs, grasses or bulb species.
Organic herbicides are not effective on Ward’s weed because only the above ground portion of the plant are killed, so the plants continue to re-sprout from live roots.
The city’s current Integrated Pest Management Plan allows the use of herbicide “if deemed necessary by supervisory staff to protect public safety; to prevent threat to sensitive species or habitats; to assist in meeting regulatory compliance requirements; or to prevent economic loss-when pests cannot be managed by other tactics.”
“We have an opportunity to potentially eradicate a new invasive species that could spread throughout southern California and beyond, said Humphrey. “If Ward’s weed is not eradicated early, the cost of invasive species treatment and the damage done to native habitats will be significantly greater into the future. “
Ward’s weed can look like anything from a single, short stem to a dense, compact shrub similar to tumbleweed. Because it is an annual plant, Ward’s weed is green in the winter, and dries up and dies in the summer. The easiest way to identify this plant is by the small, round seed pods that are found all along the stems.