Back to Basics for Weed Control - Consider Mode of Action

New-tech crops over the past 12 years have revolutionized how you farm, creating more efficient ways to stop weeds and insects in corn, soybeans and cotton. However, the rising specter of weed resistance is a concern for more producers as they struggle with ways to stop tough weed competitors.

The key is managing your modes of action and making sure that what goes in the sprayer tank is diverse enough to tackle the range of weeds in your fields. For the past few years the top weed scientists in the country have been giving talks on this topic, noting that knowing a herbicide's mode of action can help you manage tough problems.

In fact, some of those same Extension experts say that it's better to manage your fields as if you have resistant weeds, even if you don't. The easiest way to control resistance is to make sure it doesn't show up in your field.

Weed resistance isn't a new issue. In fact the list of weeds resistant to at least one herbicide mode of action is pretty long - from tried-and-true tools like atrazine to ALS inhibitors, there are weeds that shine through after a spraying. But mixing up the controls, and giving weeds a one-two or a one-two-three punch that may include new modes of action is important too.

That's growing in importance too as some species of weeds are being found to contain resistance to two or more modes of action. And knowing that can help guide your program too.

The challenge is that you have to keep up on modes of action to know what works best and how you're "mixing it up" for your farm. That's where your crop protection dealer or consultant comes in. The tank-mixes you work up and the approaches you use for 2010 can help stall the problem.

If you're already dealing with herbicide-resistant weeds, changing up your program will help keep them at bay. A recent paper published in the February edition of Weed Science notes that cotton producers weren't using resistance management strategies for two reasons.

First, many felt a new technology would come along soon to help overcome the problem. And second, a lot of producers feel that resistance will come no matter what they do because it can be spread from neighbor's fields.

Neither of those assertions is entirely true. The industry is working hard on new modes of action, but it could be years before they hit the market. As for how resistance spreads? In fact, you can create your own resistance in the field, no matter what the neighbor does if you keep hammering your weed population with only one mode of action.

This crop season is shaping up to be a doozie with the winter you've experienced, but as you make crop protection choices, look at the tools out there. Select tank mixes that add a lot of variety to the modes of action you hit weeds with. And in the long run you can keep resistant weeds under control. It's worth the investment.