Invasive Species of the Month – Brassica tournefortii

Invasive Species of the Month – Brassica tournefortii

Sahara Mustard

Sahara mustard is annual from the Mediterranean and has been spreading rapidly into coastal San Luis Obispo County. It is in Los Osos, Grover Beach, Oceano, the Nipomo Mesa and the Santa Maria River. Sahara Mustard first appeared in North America in 1927 in Coachella Valley and has spread throughout the Sonoran Desert. It grows in disturbed areas: mainly roadsides, dirt roads and construction sites. Locally it has spread from sticky seeds on pick-up truck tires, construction equipment, rodents and from wind. One of the awful qualities about this weed is that it out-competes native plants, especially annuals, simply because it grows very densely.

Sahara mustard image

Basal rosette (David Chipping)

The 3 to 12 inch deeply lobed leaves exist as a rosette which is low, only several inches above the ground. The small, pale yellow flower stalks may reach 4 feet and produce zillions of seeds (actually up to 9,000 seeds) that are viable for more than 3 years.

Controlling Sahara mustard may be done by hand pulling. It is easier to pull than Black mustard. Sahara mustard is prolific and annoyingly often grows amongst tree and shrub plantings: pulling is the only option in this instance. It is best to pull when they are emerging. Once seed pods develop, the plant will set seed after it has been pulled, so it should be removed from the site.

When away from native plants monotypic Sahara mustard may be sprayed with Telar, Milestone, Garlon 3A or Transline (they are all broad leaf herbicides). Grazing is not a good idea because there is are toxic compounds in the seeds.

– Mark Skinner

featured image: The pale yellow flower, with 4-7 mm petals, and siliques, growing to 3-7 cm long (David Chipping)

Iceplant (Carpobrotus edulis)

Iceplant (Carpobrotus edulis)

Invasive Species of the Month: Iceplant (Carpobrotus edulis)

Iceplant is a perennial in the Aizoaceae family, native to South Africa and grows in sandy areas on the coast from Eureka to Baja. This succulently leaved plant is overwhelming and carpets the land. I’ve seen outcompete giant Coreopsis and beach spectacle pod. Iceplant competes for nutrients, water, light and space. In very dry places they have long straggling woody stems. The pink or yellow flowers are beautiful and peak in early summer. The leaves root in the soil at the nodes and reproduces by seed. Seeds that passes through an animals gut germinates better.

Iceplant may be pulled and removed–which is the case at Piedras Blancas lighthouse, with spectacular results from the emerged native plant seedbank. Iceplant may be sprayed and the dead matter makes an excellent mulch for native plantings. Frost also kills Iceplant.

According to Cal-IPC iceplant was brought to California in the early 1900’s for stabilizing soil along railroad tracks. It was planted along freeways by Cal Trans until the 1970’s. Now it provides job security for weed warriors.

– Mark Skinner

Carpobrotus edulis or Carpobrotus chilense?

These two species are very similar, and the Jepson descriptions do not fully cover the overlap of features. Generally C. chilense has smaller magenta flowers (3-5 cm diameter) compared to 8-10 cm for C. edulis, which favors yellow flowers, but there is color ‘crossover’. The flower of C. edulis is pedicelled and C. chilense is sessile. The fruit of C. edulis is triangular in cross section, that of C. chilense more rounded and softer.

Carpobrotus edulis on earthquake-elevated mudflat, Shark Inlet, David Chipping

Carpobrotus edulis on earthquake-elevated mudflat, Shark Inlet, David Chipping

The photograph above shows a massive carpet of Carpobrotus at Shark Inlet. The bench in the foreground used to be pickleweed marsh until the Paso Robles earthquake caused the sand dunes to press down into the mudflat, squishing the edge of the flat above the high tide line and enabling the iceplant invasion.

– David Chipping

Invasive Species of the Month – Cortaderia jubata

Invasive Species of the Month – Cortaderia jubata

Invasive Species of the Month

Jubata grass (Cortaderia jubata)

Mark Skinner

There is an intense infestation of Jubata grass on the California coast. As almost everyone knows it mars the most
beautiful places such as Big Sur. On their web site California Invasive Plant Council (CalIPC) describes that Jubata grass is native to northern Argentina, Bolivia, Peru Chile and Ecuador. It was grown in France and Ireland from seed collected in Ecuador. It may have come to California from France and was first seen in 1966. Jubata grass has been called the “marriage weed” as honeymooners dragged the plumes behind their cars in Big Sur. Oy! What a mess!

Jubata grass flowers from late July to September. No pollination is necessary for reproduction. Flowers are female
only, which produces viable seed. Each plume may contain 100,000 seeds! Plants may have 1 to 30+ plumes. I started removing Jubata grass in the mid 1990’s with Jack Biegle and John Nowak, just north of Oso Flaco boardwalk.
I’ve been at it ever since and removed hundreds from the Guadalupe-Nipomo Dunes, San Luis Obispo, Cambria and
Vandenberg. I’m happy to report that from the many hundreds that were in the Guadalupe-Nipomo Dunes there are only about twenty remaining.

Invasive Species of the Month – Erigeron bonariensis

Invasive Species of the Month – Erigeron bonariensis

Erigeron bonariensis

Hairy Fleabane or Flax Leaved Horseweed
Family: Asteraceae, Place of Origin: South America
Hairy fleabane is aptly named: it is strigose (set with stiff bristles or hairs) throughout the plant – stems, leaves, flowers.

Hairy fleabane is an low annual, (about 8″ to 3′) and thrives in disturbed areas. I’ve seen it emerge in cracks in pavement and in areas formerly occupied by European beachgrass in the Dunes. Often, it is present with Erigeron canadensis (Horseweed), which is native to North America. Horseweed, along with another native composite, Heterotheca grandiflora (Telegraph weed) are the most unattractive weedy natives in California.

Hairy fleabane produces many urn or barrel shaped flowers, the fluffy seeds are sandy colored and distributed by the breeze. In the Dunes it is competing with other composites such as Dunedelions and Cudweeds and should be removed.

Mark Skinner

On Veldt Grass

On Veldt Grass

Image courtesy of jkirkhart35 |

Some of the most notorious invasive plants such as Carpobrotus, slender leaved ice plant, and cape ivy come from South Africa. Another quite bad one is Veldt grass (Ehrharta calycina). This bunch grass has wide (1/4″) leaves, is glaucous (grey-green) until it matures and turns maroon. From the road it has red tops which turn blond. The seed stems can reach chest height. It is a perennial that produces an incredible amount of seeds and grows throughout the year near the coast, living off fog drip, but mainly follows the rainy winter. Veldt grass is awful because it crowds and overwhelms other plants.

To be rid of it, manually pulling mature plants, including the buried crown of the plant is necessary or resprouting will occur. But this also this often stimulates seed germination. Manual removal must be repeated as seedlings appear from the seedbank. Serious infestations can be sprayed with a grasss-specific herbicide such as Fusilade. Timing is critical, especially after the first several inches of rain. Some applicators report that postemergence treatment to plants over 4 inches tall is much more effective compared to treating smaller plants. If your locale has had Veldt for a long time keep at it until the seed bank is exhausted. The task is very difficult in drought and easy in wet years.

Best wishes weed warriors.

-Mark Skinner

Invasive Species Watch

I’m pleased to start an Invasive Species Watch column to Obispoensis. I’ve been in the invasive species removal business since 1999 mainly working in the Guadalupe-Nipomo Dunes and San Luis Obispo Creek. Those that know me many not think of me as a warrior however many people (thanks CCC’s!) and I have been battling bad guys such as Arundo, jubata grass, veldt grass, European beach grass, Russian wheat grass (some of the most insidious weeds are grasses!) cape ivy and ice plant for a long time. The satisfaction of this work arrives when a formerly infested area is re-taken by native plants. The best memory I have is from 2002 when a heavy veldt grass infestation was sprayed out at the then Tosco Buffer (now Phillips 66) which was followed by a lush wildflower display of goldfields, dune larkspur, owl’s clover, baby blue eyes, blue dicks, sky lupine, and fiddleneck. I’m still working on the same weeds and I’m seeing progress: Russian wheat grass and jubata grass have been nearly eradicated from the Dunes!  In future pieces I’ll be describing specific invasive species and what’s being done to control them.

by Mark Skinner