Fact Sheet FS1350
Redroot (Amaranthus retroflexus) and smooth pigweed (Amaranthus hybridus) are annual broadleaf weeds commonly found in field and vegetable crops in New Jersey. Both species are very similar and are difficult to separate from each other in the field, especially at the seedling stage. Seeds of all pigweed species are easily transported across farms when moving soil or agricultural equipment, such as mowers or combines. Awareness of the life cycle and biology of pigweed are key to figuring out the best options for control in your fields.
Plant Description and Growth Habit
Both smooth and redroot pigweed have hairy stems in contrast with other pigweed species (Powell amaranth, Palmer amaranth, or waterhemp). Smooth pigweed can be differentiated from redroot pigweed when in bloom primarily from its many branched flower heads, and branches that are thinner and longer than redroot. Mature pigweeds have a short taproot, can reach up to six feet tall, and produce small green flowers in clusters that form in leaf stem joints and branch ends.
Control of pigweed can be a multi-year process that involves several strategies for control. Organic and no-spray farming operations will need to rely on well-timed cultivation and strategic planting to compete with the weed infestation.
|Pigweed Field Locations|
|Field||Size of Population||Suspected Introduction|
|Example: Field 4||Patchy throughout||Equipment borrowed|
Farm Decision Tool
Pigweed management is a multi-year process. Identifying existing pigweed populations on the farm and reflecting on your activities and how they impact these populations are the first steps to developing a management plan. Use the charts below to identify your pigweed populations and your current management methods, and develop a plan of action to eradicate pigweed from your production areas.
|Field 4||Example: hand weeding||Late summer|
|Field||Potential Future Strategies||Timeframe|
|Field 4||Clean equipment between fields||Throughout 2022|
- Grubinger, V. (2004). Flaming Stale Seedbeds for Weed Control.
- Lounsbury, N., Birthisel, S., Lilley, J., Maher, R. (2022). Tarping in the Northeast: A Guide for Small Farms (PDF). University of Maine.
- Mohler, C., Teasdale, J., DeTommaso, A. (2021). Manage Weeds on Your Farm: A Guide to Ecological Strategies. USDA Sustainable Agriculture.
- Mohler, C., Johnson, S. (2009). Crop Rotation on Organic Farms. USDA Sustainable Agriculture Research and Education.
- Uva, R., Neal, J., DiTomasso, J. (1997). Weeds of the Northeast. Cornell University Press.
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