AIR JUNE 24, 1998

Thank you Mark and good morning everyone. Some people may have been getting nervous about the dry weather, but I had a feeling that once we started wheat harvest we’d get some good rains. The rains the past few days have, for the most part, been a welcome sight, but be sure to watch for weed breakthroughs in your fields.

Speaking of weeds a funny thing happened on the way to reduced tillage. We saw a shift in weed problems. One thing you can say about the old moldboard plow and tandem disc, they really did a number on the root systems of perennial weeds. While it wouldn’t kill the weeds it certainly reduced the vigor and number of weeds like milkweed, dogbane, swamp smartweed and even johnsongrass and bindweed. As many producers have moved towards reduced and no tillage, the root systems of those weeds don’t get disturbed and they can really thrive and spread. Fortunately we do have some newer herbicides and newer crop technology to deal with some of these troublesome weeds. Dealing with perennial weeds requires a different approach than our standard annual weeds. When a weed is starting from a seed each spring, we want to disrupt that germination process or catch it when it is still small. We are primarily concerned with what we see above ground. A perennial weed is starting from a root shoot so our pre-emerge germination interruption herbicides have no effect. Additionally we don’t want to be in a hurry to treat that perennial weed. Early on in the season it is busy pushing everything up from the roots. Herbicide applications in the early season tends to just burn down the shoots without damaging the root system.. With most perennial weeds you are better off to wait until they start to bloom or even later. By the time these plants start to bloom they are starting to move food reserves back to the roots, so the herbicide is carried down also and more damage is done. Keep in mind that controlling a perennial weed is not a one shot, one year proposition. It may be a couple of times a year, and definitely 3 to 5 years to control the whole root system and subsequent seedling sprouts. If you have a perennial weed problem, then some of the new roundup ready crops may be just the ticket. There are some other options available so give me a call and we can talk about your particular weed problem!

This is Chuck Otte, Geary county Extension Agent, with Ag Outlook '98.

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