WEEDS!

Weeds are getting stronger and more resistant to herbicides.  And the problem is only growing.  According to recent interview from agriculture.com of Mike Owen of Iowa State University "The problem is much more widely spread than what I think many of the growers recognize."

What's adding to to the problem is many growers think once they've found a good and effective herbicide they can stick with it.  Unfortunately that's not the case.  Weeds can become resistant to a normally lethal dose of herbicide if used over and over.

The problem is it's hard to spot weeds who have become resistant to the growers herbicide.  Most of the time they aren't noticeable til September and October when they start peaking out above the soybeans.

3 Factors

There are three factors that lead to weed adaptation to the enviroment.

1. Genetic

• Mutation rates
• Mode of inheritance
• Mechanism of resistance

2. Biological

• Species life cycle of plants
• Germination biology
• Population size and density of plants

This is vitally important.  According to Jason Norsworthy of the University of Arkansas, knowing when a weed emerges, its growth rate and when it flowers can all help you find its weakness.

3. Operational

• Herbicide efficacy
• Frequency of use
• Timing of use
• Herbicide use pattern including rotations or mixtures
• Crop rotation
• Herbicide rate
• Cultivation practices

Here is where you can really do something about it.  Understanding weed biology and using diverse tactics such as planting in weed fields can help delay weed resistance.  You can also manage field borders and prevent weed seed movement as well.

"We have to manage the weed before it becomes a major issue," says Norsworthy.  Scouting your field and identifying weeds before they really can grow is the best tactic.

Now What?

There is nothing new coming down the pipeline for at least another eight years or so according to Norsworthy.  Your first line of defense should always be getting to the weed early before it matures and spreads.

Diversity is the key.  They include cultural, mechanical and herbicidal strategies.  And of course make sure your chosen herbicide is effective.  "The way to know whether or not they are effective is to look at the herbicide use history, and also recognize the resistance that do exists in your particular area," says Owen.