How to Control Weeds

The following Agriculture and Natural Resources article printed in the 2018 Winter edition of the Oldham County Extension Newsletter.

healthy pasture

Get a Handle on Controlling Weeds

Producers of everything from vegetables to pastures to wildlife plots all deal with weeds. Weeds were an even bigger problem this year with above-average rainfall. Managing weeds requires multiple strategies and planned effort. And it may require changing management practices.

Not every crop lends itself to all of these, but here are some ideas for getting a handle on weeds.

1. Know the enemy. If you don’t know for sure what the weed is, dig it up and bring it in for identification. In the case of multiple weeds, call and schedule a farm visit. Correct identification provides clues for best management strategies and timing of these.

2. Don’t allow weeds to produce seeds. Mow, pull them out, do what you can to prevent seed formation. Allowing weeds to grow unchecked every year means the weed population will continue building.

Weed seeds can lay dormant in soil for years, waiting for the right opportunity to germinate. Allowing desired forages to thin in pastures and hay fields gives weeds space to grow. Tilling may bring weed seeds to the surface to germinate and outcompete whatever you plant. Bare ground is an invitation for weed growth. Whether soil is exposed by tillage, overgrazing, or use of a total-kill herbicide, the longer it is bare the more likely it is to produce weeds.

Some weeds are biennials or perennials and have the ability to regrow from roots next season. Even then, preventing seed production is still important to reduce spread.

johnsongrass pasture weed

3. Think of weeds in terms of their life cycles. For example, weeds like ragweed and pigweed are warm season annuals. Their exact time of emergence varies with temperatures each spring. In some years, warmer spring temperatures allow warm season weeds to germinate earlier than usual. And in other years, cooler temps may delay their emergence until late May.

In cooler springs, one strategy is to consider delaying herbicide (weed killer) applications to ensure the targeted weed is actually present. Waiting to spray may also mean that planting the desired crop must be delayed.

Conversely, waiting to spray warm season annual weeds in July means they are already big and harder to control. Scout your plantings to know what’s there, and remember that timing is everything.

4. Crop rotation can be a good tool to reduce weed problems. Some crops have greater ability to outcompete weeds. In vegetable plantings, vining crops with large leaves can be rotated to areas where finer leafed plants (carrots, onions) were grown the previous season. Plants that produce a thicker canopy or a thicker stand can help suppress weeds.

Some producers rotate weedy, thinned out pastures into an annual crop like sorghum sudangrass or millet to break the weed cycle. In many cases, herbicide use is still warranted to get a handle on weeds before planting back into pasture.

waterhemp crop field weed

5. When using herbicides, make sure you understand the products and manage to make best use of these. For many products, there is a time lapse required after spraying before mowing or tilling is recommended. Allow time for the herbicide to do the job.

Instructions for use are always outlined on the product label. It’s important to understand these before making spray applications. Many herbicides require a time lapse after application before it’s safe to plant desired crop.

6. Keep good records. Document weed problems, plus management strategies that worked and didn’t work to help with future planning.

Managing weeds reminds me of a saying a farmer here once shared – ‘When you do what you’ve always done, you’ll get what you’ve always got’. Solving a problem, no matter what it is, often requires stepping out of the box and getting a different perspective. What are some of your successes in controlling weeds?

Written by Traci Missun, Oldham County Agriculture and Natural Resources Agent.

5 thoughts on “How to Control Weeds

  1. Pingback: Rehabilitating Pastures After Excessive Rainfall | Oldham County Cooperative Extension Blog

  2. Pingback: Fall Pasture Re-Seeding Strategies | Oldham County Cooperative Extension Blog

  3. Pingback: Ornamental Grass Can Be A Pasture Weed | Oldham County Cooperative Extension Blog

  4. Pingback: Troublesome Weeds: Buttercup & Poison Hemlock | Oldham County Cooperative Extension Blog

  5. Pingback: How to Manage Insect Pests in the Garden | Oldham County Cooperative Extension Blog

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