Ask the Agronomist—Weed Control

Soybean Product Manager, Mark Grundmeier, responds to frequently asked questions about post-emergence herbicide application and weed management.

Q: What tips do you have for farmers who are applying post-emerge herbicides?

A: Early season weed control is very important so that the crop can become well-established, but remember that haste makes waste! Double-check what type of seed you planted. Farmers today have a lot of options for seed products, from products that are resistant to either Roundup or Liberty to those that are resistant to both. It’s not uncommon to receive a call from someone who sprayed either Roundup on Liberty soybeans or Liberty herbicide on Roundup corn. No one likes to be out time or money, so just take an extra minute or two to double-check which traited products you have planted in each field before herbicide is applied.

Q: What weeds are you seeing in the fields right now?

A: We’re seeing a lot of water hemp, pigweed, as well as some winter annuals like marestail. In no-till fields we’re seeing a lot dandelions. Of course there’s always going to be the grasses like foxtail and large broad-leaf weeds showing up. It’s that time of year to get out in your fields and take a look for weeds!

Q: It seems like each year it gets harder and harder to control weeds; are there any steps farmers can take that will help?

A: There are 5 small steps farmers can take that will provide giant relief for weed control:

  1. Closely monitor known problem areas for tough-to-control weeds.
  2. Apply herbicides correctly. Follow the labels and guidelines, and remember that timing is critical.
  3. Don’t be satisfied with economic thresholds for weed control. Sometimes 85-95% isn’t enough; we need to fight weeds all season long.
  4. Clean equipment to prevent spreading to other fields.
  5. Surviving weeds must not be allowed to set seed. We need to get rid of as much as possible.

Q: How are farmers preventing herbicide resistance?

A: Rotating between herbicide traits is very important when fighting weed resistance. Especially with the newer traits becoming commercially available, especially in soybeans, we as a farming community need to be good stewards when handling this new technology.

Q: Is rotating crops a need or a benefit?

A: It’s best to be proactive in managing herbicide resistance before it becomes a problem. Rotating crops is a huge part of that, so is rotating the traits we’re using. We need to know what herbicides we’re using for what they do and don’t control, and what restrictions exist. Also be aware of the potential for crop injury. We have to get weeds out of fields before they get too large.

Q: How often do we need to be scouting?

A: Scouting should start right after emergence. Now is a great time to start monitoring fields weekly throughout the growing season for the most effective weed management practices. Be sure to take notes of what weeds are prevalent and where so that more informed decisions can be made for the 2017 growing season. Taking notes is critical.

If you have a question about what you’re seeing in the fields, feel free to ask! Send your questions via Twitter to @LathamSeeds, in a private message on Facebook or call our office at 1-877-GO-LATHAM (1.877.465.2842).