Houndstongue

Information

Cynoglossum officinale - Boraginaceae Family - Biennial

houndstongue_1_tile houndstongue_2_tile houndstongue_3_tile houndstongue_4_tile

Identification

Flowers: Reddish-purple or occasionally white, with five petals.
Seeds: Reproduces by seed. Each plant can produce up to 2,000 seeds which remain viable for up 3 years.
Leaves: Rough hairy leaves that are up to 12 inches long and 3 inches wide.
Flowering Time: Early summer.
Life cycle/ other: Biennial.

Impacts

Invades areas that have more than 10% bare ground and prefers gravelly alkaline soils. Does not compete well with native plants.
The seed pods (nutlets) are covered with hooked spines and provide a mechanism for dispersal on clothing and fur.
Houndstongue contains pyrrolizidine alkaloids which are highly toxic to horses. However, animals rarely eat it unless it is dried and mixed with hay.

Most effective control methods

For small infestations, houndstongue can be dug-up or hand-pulled if soil conditions permit. Hand pulling may be difficult as the taproot is strong and grows deep into the soil.
For plants that have already gone to seed, clip and bag the stalks and nutlets. Plants will not regrow the following year as each plant dies following seed production.
For larger infestations, Escort (Metsulfuron) at 1 to 2 ounces per acre (oz/A) is very effective when applied throughout the growing season. For first-year rosettes, 2,4-D applied at 2 pints/acre from late May to mid-June is effective. Second-year plants are much less susceptible to 2,4-D.
Prevent seed spread! Beware to remove all seeds from clothing, shoes, shoelaces, etc.

Control methods and timing

March	April	May	June	July	Aug	Sept	Oct
		Prev Mech Chem	Prev Mech Chem	Prev Mech	Prev Mech	Prev Mech	Prev Mech

March

April

May

June

July

Aug

Sept

Oct

Chem

Prevention (Prev) Monitor and destroy new plants before seed production.

Mechanical (Mech)) Hand pulling, digging, cutting, mowing and tilling.

Cultural (Cult) Biological control agents, livestock grazing, and revegetation practices.

Chemical (Chem) Selective herbicides based on the plant and the specific location. Check our weed fact sheets for specific control information.

Houndstongue

Houndstongue: flowers

Houndstongue: nutlets

Houndstongue: rosette

Houndstongue: plant going to seed

Houndstongue: taproot

Houndstongue: plant going to seed

Houndstongue: infestation