Department of Plant, Soil and Microbial Sciences Weeds

Purple deadnettle (Lamium purpureum L.)

Life Cycle:

Winter annual. Primarily emerges in the fall, flowering and seed set begins in early spring. Plants die with hot, dry weather in late-May and June.

Emergence:

Primarily emerges from soil depth of 1-inch or less. However, emergence can occur from 2 1/2-inch soil depths.

Seed:

Production Range: Produces 27,000 seeds per plant without competition.

Dispersal Mechanisms: None.

Longevity: Moderate to very long persistence - about 20% of seed was lost from the soil seed bank each year in a 6 year experiment. However, there have been reports of purple deadnettle seed still viable after 660 years.

Dormancy: Initially dormant, high summer temperatures break dormancy and seed germinated in the fall.

Competitiveness:

Not very competitive with small grains.

Preferred Soil/Field Conditions:

Thrives in nutrient-rich and mildly humic, loamy or sandy-loam soils.

Management:

Biological

Predation/grazing: No information.

Decay: No information.

Mechanical

Tillage: Purple deadnettle is readily controlled by tillage in the late-fall or early spring.

Rotary Hoeing: Primarily a no-till weed, not likely present at time of hoeing.

Flaming: No information.

Cultural

Crop rotation: Typically a problem of small grains, alfalfa and no-tillage systems. Planting small grains at higher populations will suppress purple deadnettle.

Planting date: Tillage in the spring and planting later (mid-May) will reduce purple deadnettle infestations.

Chemical

Application timing and effectiveness: Easily controlled with herbicides. Fall and early spring herbicide applications are generally most effective and may also suppress seed production. Please refer to E-434, "MSU Weed Control Guide for Field Crops," for herbicide recommendations.

Additional Information
Can serve as an alternate host for soybean cyst nematode.