The first true leaves of the waterhemp plant appear generally longer and more spear-shaped than other pigweeds.
Manage Tough-to-control and Resistant Waterhemp
Proliferation of resistant waterhemp can be managed by accurate weed identification and regular scouting. Scout early and often. Control waterhemp before it reaches 4 inches in height to achieve timely and effective herbicide application. Waterhemp can grow at the incredible rate of 1 to 1 1/4 inches per day, so timely herbicide application is critical.
For best control, apply a pre-emergence residual herbicide followed by post-emergence applications as needed throughout the growing season. Treating new infestations early reduces waterhemp establishment, prevents seed production and greatly improves control. Other control practices farmers may use include crop rotation, planting cover crops and using diversified weed management programs. Farmers should always use full, labeled rates and herbicides with multiple sites of action from different classes of chemistry.
Known Resistance in Waterhemp
In Illinois, Iowa, Missouri and other areas across the Corn Belt, there is documented waterhemp resistance to ALS inhibitors (Group 2), PPO inhibitors (Group 14), glyphosate (Group 9), triazines (Group 5) and HPPD inhibitors (Group 27). There has also been 2,4-D (Group 4) resistance in waterhemp documented in a native-grass seed production field in Nebraska, according to the Weed Science Society of America (WSSA). For further information on resistance confirmed by state, visit the International Survey of Herbicide Resistant Weeds.
Bayer has a broad herbicide portfolio to combat tough-to-control and resistant weeds. A well-thought-out herbicide program, using multiple sites of action, should be implemented to sustainably manage weeds. Before applying any herbicide, please read the entire label for the best possible results and to confirm that the product is effective on the weeds you wish to control. Not every product is suitable for every situation, and use of the correct application technique will ensure the best results.
Please visit our corn and soybean pages for information on a portfolio of products from Bayer to help you better manage weeds.