Don’t Wait Until You See It For Yourself

Those who know me know that I recommend that growers conduct evaluations on their own farms when making decisions about new crop production products or methods. There are some situations, though, when you probably need to act before you see something demonstrated on your own farm.  Take managing weed resistance, for example.

A couple of decades ago, walking beans was a common way for many Iowa kids to make some summer money.  While most Iowa growers know about walking beans, few of their children have done it. The introduction of glyphosate herbicide made this practice essentially extinct in Iowa. 

Last summer, the appearance of glyphosate resistant waterhemp in several parts of the state caused many growers to realize that times had changed. While glyphosate is cheap and easy to use, the resistance was inevitable. Mike Owens, Iowa State University extension weed specialist, has consistently warned growers of the need to rotate herbicide modes of actions to combat resistance, but the relative low cost and ease of using the glyphosate system has resulted in over-reliance on it.

The reality of glyphosate resistance in weeds is not in question. The disconnect seems to be more the belief that growers don’t need to take action before they see the problem with their own eyes. But once resistant weeds are established on a field, the damage is done.

Weed scientists have already identified weeds that are resistant to many of the herbicides we use today.  So far in Iowa, we can usually manage weeds successfully in soybeans using a combination of modes of action. Already in other areas, particularly in some of the southern states, growers have all but given up on raising soybeans because of the weed resistance problems.

Many growers believe that the herbicide companies will keep discovering new chemicals to keep ahead of the growing resistance. While we hear that soybean varieties will soon be available that are resistant to products like dicamba and 2,4-D, these herbicides aren’t new. And the cost of research and development – and regulation – for new herbicide products has most chemical companies sitting on the sidelines. 

The extent of resistance observed in Iowa soybean fields last year should remove any doubts that it is a real issue. Managing for weed resistance before you see it on your farm is critical if you want to avoid the problem of trying to control resistant weeds after the fact.

Many of the growers who experienced a resistant waterhemp break-out last year tried to respond by applying additional post herbicides at a stage that resulted in crop injury, reduced yield, and, unfortunately, still did not control all the resistant weeds. I’ve talked with many growers are considering switching to another system to control the break out weeds. The problem is, if this new system becomes the mainstay and they don’t rotate the systems, we’ll see weeds that develop a resistance
to that.

You’ll be money and yield ahead if you accept that the problem with weed resistance in Iowa is real and take measures now to combat it, before it shows up in your fields. For information on On-Farm Network^® herbicide trials, go to www.isafarment.com. If you’d like to participate in 2012 herbicide trials, contact Matt Sweeney at msweeney@iasoybeans.com.