At a towering 9’ tall, waterhemp steals nutrients, sunlight and yield from your fields. That theft results in dollars lost each year the weed is in your fields.
For those in the Midwest, this is old news. Waterhemp has wreaked havoc across many Midwestern states. It will continue to do so with more ferocity thanks to increased herbicide resistance. Currently, waterhemp is resistant to six herbicide groups in one or more states. Groups include: ALS (2), T1R1 Auxin Receptors (4), Photosystem II inhibitors (5), PPO Inhibitors (14), EPSP synthase inhibitors (9, glyphosate) and HPPD Inhibitors (27).
If you don’t have resistance in your state don’t think you’re in the clear. Even without resistance, waterhemp is incredibly resilient. It is a summer annual that grows 2.5” per day in certain conditions with a growth cycle opposite of the spraying window, so it can usually dodge the herbicide bullet.
Don’t lose hope just yet, it’s a tough weed, but not invincible. Seeds have a relatively short shelf life of only four or five years and seeds won’t grow from low soil depths. Tillage could be an excellent defense against waterhemp in areas where soil type and topography allows. If you don’t use tillage, remember you can still control this weed with herbicides. Employ scouting to be deliberate and timely with application—don’t let waterhemp exceed 4” tall.
When scouting look for these characteristics:
- Stems can be bright red or green
- Seedling leaves are oar-shaped
- First true leaves are oval with a notch at the tip
- True leaves are alternate, oval, hairless and waxy
- Flowers are green to dark pink with spikes
- Summer annual found in eastern and central U.S.
How is waterhemp pressure in your area? What herbicide or mechanical combinations have you used to tackle this tough weed?