Giant Reed (Arundo)
Pampas and Jubata Grass
Cape Ivy (German Ivy)
Periwinkble (Vinca Major)
Artichoke Thislte (Cardoon, Wild artichoke )
Fennel
Perennila Pepperweed (Tall Whitop)
Mustard
Acacia
Blue Gum Eucalyptus How to Remove Problematic Invasive Plants

How to Remove Problematic Invasive Plants

Removal and treatment options for these and other invasive plants are availble for the California Invasie Plant Council (www.cal-ipc.org) The Weed Workers's Handbook, or can be downloaded via this link.

The Giant Reed (Arundo donax)

This giant reed is a tall perennial grass that typically forms dense stands in disturbed sites, sand dunes, riparian areas and wetlands.

Description

Giant reed grows up to 30 feet tall. The leaves are alternate, up to a foot long with tapered tip, slender and smooth, but coarsely serrated margins. They are gray green and have a hairy tuft at the base. The leaves point straight out, droop or lie folded and at the base of each are a tuft. As the leaves dry they turn to a pale brown like papyrus. The hardy stalks are hollow, about one inch in diameter and resemble bamboo canes. The roots are tough and fibrous and form knotty, spreading mats that penetrate deep into the soil.

Reproduction

The inflorescence is cream to yellowish brown and appears from March to September in the form of upright feathery plumes as long as two feet. Arundo does not produce fertile seed in California. Instead, it produces vegetatively, by underground rhizomes. Riparian flooding dislodges clumps clumps of arundo and transports it downstream, where it can root from broken stem nodes and rhizomes. Fire appears to stimulate new growth.

Impact

Arundo is threatening California's riparian ecosystems by out competing native species, such as willows, for water. Its rapid growth and high water uptake allow it to out compete native vegetation and form monocultural stands. Noxious alkaloids contained in the plant deter wildlife from feeding. Stands of dry leaves and canes are flammable.

Treatment Options

Disposal

Both treated and not treated stems can be left on-site to decompose, although they breakdown very slowly. If left to compost, the essential thing to remember is to keep it away from the water. For stem that have not been chemically treated and in areas where it is feasible, the debris can be burned. Otherwise the canes can be chipped into very small pieces for mulching. The stems are easier to chip when dried and you will need a heavy-duty chipper to handle the plant's fibrous canes. Chipped materials can be disposed of in green waste containers, or spread out to dry and possibly sprayed with herbicide if any regrowth occurs from the chipped debris. Stem pieces that have no nodes or only one node will not reproduce.

Pampas and Jubata Grass
(Cortaderia selloana or Cortadaria jubata)

Description

Pampas grass is the common name used for both Cortaderia species. To clarify this discussion Cortaderia jubata will be called jubata grass, while pampas grass will refer to only C. selloana. Both species are rapid-growing perennials that form large clumps. Jubata grass is found only in coastal areas, but pampas grass also infests more inland locales. Both are found in disturbed areas, slopes, cliffs coastal scrub and forest clearings.

Jubata leaves reach a height of 5-7 feet at maturity. The dark green leaves have sharply serrate margins. The flowering stalks can tower to 20 feet above the mass of spreading leaves at the base. The inflorescence, a showy plume ranges from pink to violet, turning creamy white or golden in maturity, typically appears from July to September.

Pampas grass leaves are gray-green and narrower than those of jubabta grass. The leaves tend to curl at the tips. The flower stalks grow only a little taller than the mound of leaf blades, giving pampas grass a more rounded appearance than jubata grass. The plumes are paler (generally pale pink to silvery white) than those of jubata grass.

Reproduction

Female jubata grass plants produce see asexually by apomixes. Thousands of seeds are genetically identical to the parent plant and then wind dispersed. Plants live for over a decade, and within their lifetime will develop huge root masses. New seedlings often grow on the dead mass of the parent plant, so what appears to be one plant is often several generations, growing one on top of the other. In contrast to jubata grass, pampas grass produces seeds only sexually, not apomictically, so both sexes of plants are necessary for pollination and seed production. Both grasses can spread vegetatively from tillers or fragments of the mature plant that root in moist soil.

Impact

Pampas grass is the more widespread species statewide, but jubata grass is considered more invasive in coastal areas. In forest gaps, both species can prevent the growth of saplings by limiting available water and nutrients. Both readily establish in disturbed areas including landslides, road cuts and cliff faces. Seed are wind dispersed and populations expand quickly in coastal areas, significantly reducing grasslands, scrub and rocky outcrops habitats. The sharp, sawtooth edged leaves can cut human skin. Both grasses increase the risk of fire when leaves dry out or die back.

Key Factors

Treatment Options

Disposal

To prevent resprouting, turn the whole uprooted mass upside down and leave it in place to dry out. Small stringy roots left in the soil will not regrow, but all parts of the main root mass must be at least several inches away from the ground.

Place cut plumes on top of cut grass leaves. To prevent any seeds from being blown away, make a “pampas sandwich” by covering the seed heads with a second layer of foliage. Some practitioners bury the seed plumes under something more substantial than the leaves, as they can dry out and blow away - with the seeds! Finding a way to leave the plumes behind means you won’t have to have heavy bags off-site, especially in steep, remote areas. Given that jubata grass seeds don’t need to be pollinated, it’s important to cover or remove them as soon as possible.

Follow- Up

Check for resprouts twice a year.

 

CAPE IVY

Delairea odorata

(formerly known as German ivy,Senecio mikanioides) Sunflower Family (Asteraceae)


D ESCRIPTION

Cape ivy is a climbing perennial vine usually found in coastal and ripar- ian areas and on disturbed moist sites.However,it is a highly adapt- able species that will proliferate

in a wide range of ecosystems. Both the leaves and stems

store water, making the plant drought-tolerant. A single leaf grows from each node and measures

1–3 inches long. The succulent leaves are smooth and bright green with pointed lobes. The under- ground stolons are purple. Cape ivy

is commonly confused with native

wild cucumber (Marah fabaceus),another vine with similar leaves. Unlike Cape ivy, however, wild cucumber has thicker stems, spiraling ten- drils, hairs on the leaves, white flowers that bloom in spring, and spiny fruits.

R EPRODUCTION

Cape ivy grows vigorously, particularly from February to June. It reproduces vegetatively by rooting from stem, stolon, or petiole (i.e., any part of the plant except the leaf blade) that touches the ground. Infestations can be spread by a variety of means, such as machinery or water, which carries fragments downstream. Cape ivy has no taproot, only shallow adventi- tious roots that grow to 4 inches deep in the soil. In areas with little summer moisture or with frost Cape ivy will experience some dieback, only to resume growth with the fall rains.Small, yellow flowers with green tips bloom between December and February. Cape ivy seeds have a

hairy apex and are wind-dis- persed. However, most seeds produced in California appear to be sterile.

I MPACT

A dense, sometimes heavy, and contin- uous mat of Cape ivy can blanket native vegetation. Cape ivy contains alkaloids that are potentially toxic to fish.

K EY F ACTORS

u Reroots from fragments left in the soil.

u Frequently grows among poison oak, stinging nettle, and black- berry.

u Thrives near moisture.

T REATMENT O PTIONS

Removing Cape ivy requires precision, as every little part of the stem needs to be removed. Given the time and resources that controlling Cape ivy demands,practitioners have found it is sometimes advantageous to focus on removing the Cape ivy around the perimeter of a patch, rather than all-out removal.The control method chosen depends on patch size and isolation, the resources available for control, and the threats posed by Cape ivy to valued resources.

 

Invasive plant descriptions and removal protocols from The Weed Worker's Handbook, a publication of the Watershed Project and the California Invasive Plant Council, 2004. (See bibliography for ordering information)