Last year’s weeds could make a comeback this year — plan now

If your pasture had weed issues last year, chances are that some of those same plants will be making a comeback again.

Many times, we fail to notice weeds until they become a major issue we have to deal with, which is well past the point our control measures are most effective. From ragweed to thistles, being proactive with management can make your weed problems easier to manage this year.

As with any pest issue, the first step for pasture weed management, is proper identification. Often weeds that may have been a problem are annual species taking advantage of weather conditions. We often see this during or following a dry period, where species like ragweed, snow-on-the-mountain, and sunflower come out in force.

The cheapest way to deal with these opportunistic invaders is with proper grazing management. Research on ragweed in pastures has shown that numbers are worst in pastures with an open canopy during the late May-June time period. Not only does this provide sun and space for seeds to germinate and grow, but also shows that the surrounding plants are dealing with some sort of stress and will not be as competitive as normal. By providing proper rest and strengthening the health of pasture plants we want, annual weeds can be out competed.

In severe cases, herbicides can help control these problems, but I’m a fan of trying grazing management first. Often annual weeds are a symptom of deeper issues, not the cause. In some cases these species can be beneficial, providing cover and keeping something growing during droughts. We just don’t want them to end up taking over.

On the other end of the spectrum are weed species we know we will have to deal with. Species like musk thistle, leafy spurge, and any other weed on a state or local noxious weed lists are on another level of aggression. These plants can establish a foothold and despite our best management, slowly take over a pasture.

While grazing properly can help slow spread, we typically need to take additional control measures to get these problem weeds under wraps. For our thistle species, plumeless, musk, and Canada, herbicide treatment works best when they are still in the rosette stage, which is right now. While they may be a bit more difficult to spot as a low growing rosette, control now means very few plants will live to produce seed this summer. For annual species like plumeless and musk, this can greatly reduce numbers the following year. If this management is repeated for multiple years in a row, infestations can be brought to heel.

Some herbicide options to consider include Milestone, Grazon-Next, Gunslinger P+D, Chaparral, Cimarron, Curtail, or a tank mix of dicamba and 2,4-D. Select the herbicide that best fits your operation. Some on this list may have action against other problem weeds, essentially giving you a 2 for 1 deal if applied correctly.

Perennial species like Canada thistle pose a bit more challenge. Herbicide application may not always kill a well-established perennial plant, but still may serve a purpose by weakening it and preventing seed production. Rosette applications of Curtail, Wide-March, Telar, Cimmaron, or Gunslinger P+D are all options to consider. For all herbicides, always be sure to read and follow the label’s directions when applying.

Managing pasture weeds starts now in the spring. Whether changing grazing management or using a herbicide treatment, properly identify the target, choose the option that makes sense, and apply the control in a timely fashion. Time spent well now will result in less weed issues this summer and fall.

— Ben Beckman is a beef systems Extension Educator serving the counties of Antelope, Cedar, Knox, Madison and Pierce. He is based out of the Cedar County Extension office in Hartington. You can reach him by phone: (402) 254-6821 or email: ben.beckman@ unl.edu.