The issue: Lambsquarters

Common Lambsquarters (Chenopodium album) is a summer annual that grows up to 6 feet tall. In later summer it may produce seeds at less than one inch tall. Research indicates lambsquarters acts as an alternate host for many diseases that infest common field crops, vegetables and landscape plants.

Cotyledons are lanceolate and the true leaves are egg-shaped with irregular teeth and wavy margins. The plants can be found in any disturbed area: rights-of-way; gardens; cultivated fields; poorly managed pastures.

Lambsquarters is edible, but still very invasive.

Lambsquarters reproduce only by seed. Most germination occurs early spring, but there is also some summer germination. Average seed production is 72,500 seeds per plant.

Integrated pest management options:

· Prevention: Feed weed-free hay; keep ditch banks free of seed-producing plants; clean equipment; use weed-free seeds.

· Mechanical: Hoe or hand dig small plants — weed early and shallow two to four times in first month of season; pull large plants; dispose of any flowering or fruiting plants; mowing reduces seed production.

· Cultural: Cultivation when plants are small; natural mulch in flowerbeds 4 to 6 inches deep; weed barrier; weed burner on young plants.

· Biological: Field mice, sowbugs, millipedes, crickets, slugs and carabid beetles all feed on soil-surface seeds.

· Chemical: Pre-emergent products containing dichlobenil, oryzalin or trifluralin in late fall or early spring; burn-down products such as pelargonic acid or diquat on small plants; glyphosate, 2,4-D or triclopyr on larger plants before blooming. Be sure the target weed and crop or landscape situations are listed on the product label. Always read and follow herbicide label directions.

Combine them: Lambsquarters seeds can remain viable over 70 years — a long-term program is essential. Combine different IPM options over a period of years to help improve the effectiveness of your efforts.

For more information, contact Ron Patterson, University of Idaho Extension horticulture/agriculture educator in Bonneville County.