Weed scientist from across the North Central region are preparing a series of bulletins to address concerns about glyphosate-resistant weeds under the GWC (Glyphosate, Weeds, and Crops) Series title. I have just received the first two bulletins on the biology and management of horseweed and wild buckwheat.
Horseweed and Wild Buckwheat Bulletins Available
Chris Boerboom, Ext. Weed Scientist
Weed scientist from across the North Central region are preparing a series of bulletins to address concerns about glyphosate-resistant weeds under the GWC (Glyphosate, Weeds, and Crops) Series title. I have just received the first two bulletins on the biology and management of horseweed and wild buckwheat. I will be sending some advance copies to county Extension offices and will have copies at other training events throughout the year. If you need a large number of copies for distribution in Wisconsin or training, please let me know. They are not available through UWEX publications. If you can=t wait until you receive a hard copy, you can view them on line at the following addresses.
GWC-9: Biology and Management of Horseweed (http://www.ces.purdue.edu/extmedia/GWC/GWC-9-W.pdf)
GWC-10: Biology and Management of Wild Buckwheat (http://www.ces.purdue.edu/extmedia/GWC/GWC-10-W.pdf )
The bulletin on horseweed is especially appropriate right now as we are starting our burndown spray season and it highlights adding 2,4-D to glyphosate for resistance management.
Horseweed quick facts
- Single plants produce 200,000 seeds per plant and seed is easily wind dispersed.
- Seed is essentially non-dormant so as it falls to the ground in the fall, it is ready to sprout.
- Horseweed is often called a winter annual, but it grows and competes with soybeans all season long whereas other winter annuals mature and die early in the summer.
- Horseweed has cases of resistance to glyphosate, ALS, triazine, and paraquat herbicides so resistance management is justified.
The horseweed bulletin highlights these critical principles for horseweed management.
- 2.4-D ester should be included in preplant herbicide treatments when possible.
- Herbicides should be applied before horseweed plants are 4 to 6 inches tall.
- Herbicides applied in the fall will control emerged horseweed, ut may not adequately control spring emerging horseweed.
- Spring applications prior to early May should include a residual herbicide to control later-emerging plants.
More specific recommendation on herbicides and options at different applications timings are also included in the bulletin.