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.