Description: Pampas grass is a fast growing, densely tufted perennial grass. It

forms a large clump of long, narrow, leaves that grow up to 5-7 feet tall. The leaves are flat or folded and have sharply serrated margins. Stems have huge, feathery flower plumes that grow higher than the clumps of foliage. Pampas grass and Jubata grass appear similar and are both invasive plants. History of Pampas grass: Pampas grass

is native to South America (Argentina, Brazil, and Uruguay). Pampas grass was introduced to California in 1848 as an ornamental plant, and used in gardens as a hedge, focal point, and wind breaks. For production purposes nurserymen in California selected the showier female plants of Pampas grass and propagated through vegetative cuttings. However in recent years some nurseries have propagated pampas grass from seed. This introduced the male seeds into the environment causing the escape of the plant from gardens to natural areas. Jubata grass was also introduced to California in the late 1800’s as an ornamental plant. Unfortunately Jubata grass seed was accidentally used to propagate nursery stock, releasing the invasive variety to natural areas as well.

Injury Action Level: Pampas grass was added to the monitor list of the State

of Washington in 2007. Four escaped populations have been verified late in 2013. Thurston County has proposed listing the species for control countywide in 2015. The County Weed Board has also requested the State Department of Agriculture quarantine the sale of this plant throughout the state. Once the State Weed Board classifies Pampas grass and places it on the weed list, prevention of all seed production will be required.

Varieties: Andes Silver; Bertini; Gold Band; Monvin; Patagonia; Pumila; Pink Feather; Silver Comet; Sundale

Silver; Sunstripe; Albolineata; Aureolineata; Sunning Dale Silver; Pink Pampas; Black Pampas; Purple Pampas

Control Options: Thurston County’s Integrated Pest Management emphasizes cultural, biological, and manual

control methods to keep pests and vegetation problems low enough to prevent damage. The goal of Thurston County’s Integrated Pest Management is to minimize the use of pesticides by utilizing and providing information about the most effective control options that are available and practical.

► Cultural / Habitat Do not intentionally plant pampas grass in your landscape. Report any escaped plants to the Noxious Weed Control agency.

Pampas Grass (Cortaderia selloana ) , Jubata Grass (Cortaderia jubtata)

I N T E G R A T E D P E S T M A N A G E M E N T P R E S C R I P T I O N

Impacts: Pampas grass is highly invasive due to its broad habitat requirements, and its ability to tolerating a wide range of temperatures. Its prolific seed production, rapid growth and accumulation of above-ground and below-ground biomass allows it to acquire light, moisture, and nutrients that would be used by other plants. It can be damaging even at low densities because of the amount of cover it can occupy. Pampas grass creates a fire hazard with its excessive build up of dry leaves and flowering stalks. Plants can flower even in their first year of growth, and some established plants can flower twice during the same season. Pampas grass flowers need pollen from another plant to develop seeds. An individual inflorescence can produce 100,000 seeds, and a large clump can produce a million or more seeds. Jubata grass is also highly invasive with the same properties as Pampas grass. One difference is that Jubata grass is less tolerant of extreme weather conditions. Therefore the threat from Jubata grass is applies only to Western Washington, whereas Pampas grass threatens both sides of the state.

Spread occurs by wind-blown seed or by people using mature inflorescences in decorative arrangements or using plants in landscaping. Seeds have been reported to disperse over twenty miles under windy conditions. Pampas grass can also reproduce from fragmented tillers (short root rhizome or runner).

WSNWCB WSNWCB

Foliar Application of Roundup Pro™ (a 41% glyphosate product):

As an alternative to spraying entire plants, you can cut away the stems and taller portions of the foliage, once the new growth is a couple feet tall then spot apply herbicide to the re-grown vegetation. This can make treatment of plants near landscaping or more desirable vegetation possible. Monitoring for re-growth is important with either technique, as plants that appear dead soon after spraying may survive and re-grow the following year. Check for re-sprouts twice a year.

Products containing the active ingredient imazapyr (Habitat™, NuFarm Polaris™, etc), effectively control pampas and are considered “moderate in hazard” by Thurston County’s review process due to chemical mobility and persistence.

Applications of imazapyr products require a licensed applicator.

Spot applications with imazapyr products are effective when the herbicide is sprayed directly onto the plants (avoid spraying other desirable plants). Spray each plant thoroughly on the stems and leaves enough to be wet but not dripping. Apply to re-grown vegetation in spring or mature vegetation during fall with 1-4% solution.

Do not use on areas where roots of desirable vegetation may extend and be exposed to potential injury.

Timing: Apply to actively growing foliage during the spring and summer or fall before a killing frost. In general, fall treatments seem to be somewhat more effective than spring or summer. Bagging and disposing of mature plumes is essential to reduce further spread of the species even with treatment. READ AND FOLLOW ALL LABEL DIRECTIONS .

REFERENCES:

California Invasive Plant Council, Invasive Plants of California ’ s Wildland:Cortaderia Pampas

http://www.cal-ipc.org/ip/management/ipcw/pages/detailreport.cfm@usernumber=33&surveynumber=182.php

Oregon Department of Agriculture, Noxious Weed Control Plant Profiles: Pampas Grass

http://www.oregon.gov/ODA/PLANT/WEEDS/profile _Pampasgrass.shtml

The Weed Workers ’ Handbook, by The Watershed Project and California

Invasive Plant Council, 2004, pages 96-98. Thurston County Noxious Weed Control

11834 Tilley Rd. S Olympia WA 98512

Phone: 360-786-5576

WSNWCB ► Manual / Mechanical Small plants can be hand pulled or dug out with a shovel or pick. Large, es-tablished plants may require cutting the tops first before attempting to dig out their large root masses. Carefully cut and dispose of all flower plumes. Even immature flower stalks should be disposed of as they are capable of maturing and spreading seed after removal. Root material should also be contained as new plants can start from root fragments, and roots left in contact with soil can re-sprout. Be sure to wear gloves and protective clothing, as the serrated leaves can cause injury.

► Biological There are no biological control agents available for Pampas grass.

► Chemical: Two herbicides are effective in treatment of Pampas grass. Prod-

ucts containing glyphosate should be used where other sensitive plants are nearby. At sites with escaped populations of Pampas grass present, the product imazapyr should be use, unless there are other sensitive plants nearby. Spot treatments of glyphosate (the active ingredient in Roundup Pro™ and many other brands of systemic herbicides) are effective for controlling Pampas grass. Spot treatment means you treat only the weed you wish to control without treating the surrounding soil or other vegetation. When applying spot treatments, spray the leaves and stems of each plant thoroughly enough so that they are wet, but not dripping. Herbicides labeled for spot treatment generally recommend mixing the product with water to create a specified percentage solution. For example, the Roundup Pro™ label recommends mixing a 1.5–2% solution for hand-held or spot applications for control of pampas grass (University of California Cooperative Exten-sion reports effective control of Pampas grass at 2%). Only products with an initial glyphosate concentration of 40% or greater should be used when diluting for per-centage solutions (this generally excludes pre-mixed/ready-to-use products).

Rates, at 4 lb. per gallon A.I.: 2%

To 1 gallon of water add: 2.66 oz. Roundup Pro™

1 fluid ounce = 2 Tablespoon