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Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Avenue, Room 1000, Portland, OR 97204

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What is being done about it?

The City of Portland hires licensed contractors to survey and treat garlic mustard plants along roads and stream corridors in Portland during the spring and summer.  The seeds are now too mature for effective chemical treatment, but crews and city staff continue to handpull plants.  We have reached the point in the year where pods are dry and dropping seed, dramatically increasing the possibility of inadvertant seed spread.  The City of Portland has officially stopped garlic mustard management for the 2014 season;  partners are strongly encouraged to do likewise.  Fall treatment of rosettes may resume when regular rain returns.   

(last updated:7/2/14 MRB)

Areas treated by Environmental Services so far include:


Areas managed in 2014 Treated on
NW Barnes/Burnside/Skyline triangle  4/10/14
NW Skyline Blvd (Cornell-Germantown) 4/10/14
NE Russell @ 87th 4/28/14
N Portland Rd 4/28/14
NE Columbia @ 33rd 4/28/14
NW Cornell 4/29/14
NW Thompson 4/29/14
NW 53rd 4/30/14
NW Greenleaf 4/30/14
NW Skyline Blve (Greenleaf-Cornell) 4/30/14
W Burnside 5/1/14
NW Skyline (Burnside-Hwy 26) 5/1/14
SW Humphrey 5/1/14
SW Dosch @ Patton 5/1/14

SW Boones Ferry (Terwilliger-county line)

SW Terwilliger (Boones Ferry-county line) 5/1/14
SW 4th (Boones Ferry-trailhead) 5/1/14
SW Palatine Hill (Palater-Boones Ferry) 5/1/14
SW Taylors Ferry (Boones Ferry-Macadam) 5/1/14
SW Barbur Blvd @ Hwy 10 5/2/14
SW Vincent 5/2/14
SW Broadway (Humphrey-Greenway) 5/2/14
SW Market stairs 5/2/14
SW Montgomery 5/2/14
SW Sherwood (east) 5/2/14
SW Sherwood (west) 5/6/14

SW Hewett

SW Patton (Scholls-Humphrey) 5/6/14
SW Shattuck (Patton-Hamilton) 5/6/14
SW Ormandy 5/6/14
SW Greenleaf 5/6/14
SW Greenhills Way 5/6/14
SW Fairmount/Talbot/Talbot Terrace & all side roads 5/6/14
SW Macadam (Sellwood Bridge-Miltary) 5/7/14
SW Beaverton-Hillsdale Highway 5/7/14
NW Germantown Rd. 5/12/14
SE 122nd/117th/Flavel/Dierdorff 5/13/14
Linnton 5/14/14
NW Springville Rd. @ St. John's Bridge 5/14/14
NW Fairfax 5/14/14
NW Albemarle 5/14/14
SW 45th (north of Multnomah) 5/14/14
SW Multnomah Blvd 5/14/14
SW Lancaster 5/15/14
SW Maplecrest @ Marshall Park 5/15/14
SW Taylors Ferry (east of 26th) 5/15/14
NW Skyline Blvd (Cornell-Germantown) [2nd pass] 5/15/14
NW Barnes/Burnside/Skyline triangle [2nd pass] 5/15/14
SE Thorburn 5/16/14
SW Taylors Ferry (49th-62nd)/Pasadena [handpull] 5/20/14
SW 48th/45th/Vermont/Shattuck [handpull] 5/23/14
Fairmount Loop review + Northwood [handpull] 6/3/14
locations in bold were treated in the last 14 days  


Current Phase (in bold)

Description of Garlic Mustard In Each Phase



Like many plants, garlic mustard changes form several times over its lifetime. A typical garlic mustard plant forms as a seedling in the spring and overwinters as a rosette, a low-growing cluster of leaves typically one to six inches tall. The rosette form is easily confused with several native species, and is often hard to find under winter's leaf litter.




With longer, warmer days in March and April, garlic mustard rosettes undergo a change called bolting. The stems lengthen and leaves go from round to triangular.  Buds form at the top of the building cluster of leaves.




After a sufficient number of warm, light days in April or May, the buds atop bolting plants will open into garlic mustard's characteristic four-petaled white flowers. The flowering stage of garlic mustard typically lasts three to four weeks. Herbicide treatment is most effective during this phase. Roots not removed during pulling will likely form a new flowering plant in a few weeks.


Seeds Forming


Seed formation occurs over the course of two to three weeks. Many plants will display flowers at one end of the bud cluster and new seed pods at the other end. By the time all flowers have formed seeds, it is typically early June in the Portland area. Herbicide treatment can be done on a limited and considered basis. Pulling should still attempt to remove all roots. All pulled plants should be bagged and disposed of in the trash, to prevent spread in yard debris.


Seeds Ripening


Seed ripening goes on for four to six weeks until the plants begin to dry out, typically in early to mid-July. Pulling can be done in this phase, without regard for root re-growth, but MUST stop when plants begin drying. No herbicide treatment should be attempted in this phase.


Seeds Ripe Don't pull!


Newly-dry seedpods will explode at the slightest touch, depositing seeds in clothes and hair and making the well-meaning puller an ideal vector for infesting new areas.