In 2016, weed control was a challenge. Farmers, consultants and applicators had to use the kitchen sink approach to manage weeds and still ended up with poor results. We are all aware that glyphosate resistant weeds have been present in our corn and soybean fields for some time now. There have been a handful of problem fields each year, but on most occasions good weed control was achieved until the past couple of seasons.
It is easy to blame the weather conditions, but the weather is always a challenge when trying to treat weeds. We increase rates or add additional products each trip across the field, but the Mode of Actions we use remains the same each year. This only increases the risk of weed resistance developing. To maintain the upper hand on weeds, we must embrace new technologies and rethink our management strategies.
The Roundup Ready (glyphosate tolerance) trait in corn and soybean has been the popular seed choice for farmers, with only a few weeds developing resistance to glyphosate along the way. Most of the weeds we struggle to kill today were resistant to other herbicides long before glyphosate became so popular. There are other herbicide tolerance traits available to provide some additional control, but should not be considered a long term fix for weed resistance. Liberty Link soybean have been used for a while now and Dicamba tolerant soybean will be widely available in 2017. Proper use of these new traits will be necessary in managing and preventing weed resistance.
Weed problems in soybeans usually starts with missed weeds in the corn. We have over used and relied on the same mode of action to control weeds in the soybeans, but in many cases we have followed suit in the corn as well. There are many more herbicide options available in corn, and we need to mix it up a little more. Resistance management should be viewed as a long term plan, spanning multiple seasons. Rotate between different crops, rotate between different modes of actions, and always use multiple modes of action with every treatment.
If you have a weed resistance problem, you will need to consider using new herbicide tolerant traits to get a handle on the weeds. Please remember that relying on a single mode of action is what got us in this mess, and we don’t want to repeat the same mistakes. Mix the traits and Mode of Actions up each season. With serious problems, consider using tillage to reduce weed seed germination and mix up the spectrum of weeds that emerge.
We are faced with a challenge, a tough opponent in resistant weeds. Take some time to scout your fields after a herbicide treatment, and give a fair evaluation about the level of control. Keep notes on products used and which weeds survive. We can use this information to better plan our attack next year.