Now that we are in the latter stages of our small grains harvest, it is time to start looking at those fields and taking a look at what is coming up through the stubble. The old saying, “an ounce of prevention is worth a pound of cure,” most assuredly applies when it comes to trying to control winter annual weeds like cheatgrass and jointed goatgrass and perennials like dandelion and Canada thistle.

In a recent article written by Jeff Stachler, NDSU and Minnesota Extension weed specialist, here is what he had to say: “Now is the time to begin applying herbicides for the control of winter annual weeds, simple perennials such as curly dock and dandelion, biennials such as biennial wormwood, and in some cases cool-season perennial weed species. This is especially true for no-tillage fields, but also for those fields receiving tillage other than moldboard plowing. For fields in which tillage is planned, apply herbicides at least five days prior to tillage. Herbicides may be applied within a few days of crop harvest or until the soil is frozen. Based upon research across the Midwest, the most consistently effective control of dandelions is obtained with fall herbicide applications. The best way to drastically reduce or stop seed production of winter annual species is with fall herbicide applications or effective fall tillage. It is always better to apply herbicides in the fall under less than ideal conditions, than to wait until spring to achieve marginal control of these types of weed species, especially dandelion.”

As a rule of thumb, most treatments should be made before the first killing frost. According to MSU Extension weed specialist Fabian Menalled, herbicide options for controlling winter annuals with a fall application include Stinger, WideMatch, Maverick, Olympus and Osprey. Careful consideration should be given to which herbicide you use because there are some rotational crop restrictions with certain products. Some small grain products have restrictions of up to 36 months so, as always, make sure you read the label. The reason for applying herbicides before the first frost is so that the plant is healthy enough to actually absorb the product that you are applying to it. If asked, most people would probably assume that a plant weakened by a frost and/or freezing temperatures would be easier to control with sprays, but this is not the case.

To make sure that the herbicide you are putting on gets taken up by a plant, it is best to apply it when temperatures are expected to be in the 60-65 degree range or above. Before applying check the field and see how much green weed tissue is in it. Quite simply, if there are not many green leaves, there will not be much absorption of the product by the weeds.

Just a side note, while I am only discussing control of weeds in crop fields in this article, the same would apply to your home lawn. If you have problems with dandelions or Canada thistle in your yard, you may consider trying to control them this fall and they may be less problematic next spring.

As always, if you have questions, feel free to give me a call at 433-1206 or send an e-mail to tfine@montana.edu.