Mark VanGessel, Extension Weed Specialist; mjv@udel.edu
This time of year, Palmer amaranth plants that survived earlier weed control efforts—or emerged later in the season—are now pushing through the crop canopy. It’s critical to remove these plants before they flower and set seed, as doing so is key to long-term management.
When pulling Palmer amaranth, keep in mind that the plants can regrow if their stems remain in contact with the soil. To prevent this, shake soil from the roots and lay the pulled plants across the top of the crop canopy. This helps reduce the likelihood of regrowth and saves you from having to carry them out of the field.
For those preparing fields for fall planting, be aware that stem fragments of Palmer amaranth can also take root. Plants that regrow from cut stems tend to grow faster and stronger due to the stored carbohydrates in the stem tissue—giving them a major advantage over seedlings.
To reduce the risk of regrowth from stem fragments, consider the following strategies:
- Apply paraquat to the field before tillage (note: take precautions to avoid drift onto desirable plants).
- Allow the field to rest for a few days after initial cultivation, then make a final pass with the field cultivator to disrupt any new rooting.
- Scout and rogue fields regularly to remove any Palmer amaranth emerging from cut stems.
Staying vigilant now can greatly reduce your weed seedbank for future seasons.