Diffuse Knapweed
Centaurea diffusa Lam.
Annual or biennialUp to 2 ft
Grayish green and hairy, with mostly white flowers and spine tipped seed heads.
Linaria genistifolia ssp. dalmatica (L.)
Dalmatian Toadflax
Identification
Dalmatian Toadflax
Linaria genistifolia ssp. dalmatica (L.)
- Life cycle
- Perennial
- Height
- Up to 3 ft
Dalmatian toadflax is a perennial up to 3 feet tall that reproduces by seed and root stalks. Leaves are dense, alternate and smooth edged, and the upper leaves are broad based.
Flowers grow in the axils of the upper leaves. They are two lipped, 3/4 to 1.5 inches long with a long spur, yellow with an orange, bearded throat. The fruit is a two celled capsule with many irregularly angled seeds.
It is an aggressive escaped ornamental. A deep root and waxy leaves make control very difficult.
Control
Controlling dalmatian toadflax
- Best timing
- Treat during flowering or in late fall.
- Mowing and pulling
- Keep competitive forage at the right stocking rate. Burning does not work because the soil does not get hot enough to kill the roots.
- Herbicide
- Picloram (Tordon), imazapic (Plateau) and chlorsulfuron (Telar), at maximum use rates.
- Biological control
- The stem boring weevil Mecinus janthiniformis is the most successful agent and can reduce stands fairly quickly.
Always follow the product label, and check rates in the North Dakota Weed Control Guide from NDSU. Your county weed control officer can tell you what fits your land. Source: NDSU Extension W1411 (December 2025).
Keep Looking
Other weeds on the state list
Leafy Spurge
Euphorbia esula L.
PerennialUp to 3 ft
Milky sap, narrow leaves and deep, spreading roots.
Musk Thistle
Carduus nutans L.
Biennial or winter annualUp to 7 ft
Nodding rose to purple flower heads. One plant can make 20,000 or more seeds.
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