🌿 Weed
ANX-WEED-0000249
Redroot Pigweed
Amaranthus retroflexus
Redroot Pigweed (Amaranthus retroflexus), an annual broadleaf weed of the Amaranthaceae family.
- Family
- Amaranthaceae
- Growth habit
- Broadleaf
- Life cycle
- Annual
- Invasive status
- Naturalized, widespread
- Native region
- Central America and southwestern USA, now naturalized worldwide.
- Reproduction
- Seed - a single plant can produce over 100,000 seeds, which remain viable in soil for years.
Environment
Habitat & Growing Conditions
- Habitat
- Cultivated fields, gardens, disturbed and waste ground.
- Climate requirements
- Warm temperate to subtropical; thrives in full sun and hot weather.
- Soil types
- Tolerates a wide range of soils, especially nitrogen-rich, disturbed soil.
Impact
Crops Affected & Economic Impact
- Affected crops
- Maize, soybean, cotton, vegetables, sugar beet
- Competition impact
- Aggressive competitor for nitrogen, water, and light; heavy infestations can cut yields by 30-50% in row crops.
- Economic impact
- One of the most common and economically damaging broadleaf weeds in row-crop agriculture worldwide.
Management
Control Methods
- Control methods
- Shallow cultivation while seedlings are small, mulching, crop rotation, and hand-pulling before seed set.
- Organic control
- Repeated shallow hoeing/harrowing at the seedling stage, stale seedbed technique, dense cover cropping to shade it out.
- Chemical control
- Pre-emergent herbicides (e.g. atrazine, metolachlor) and post-emergent broadleaf herbicides; resistance to glyphosate and ALS-inhibitors has been reported in some populations.