Broadleaf Weed Control

Steve Allgeier
Carroll County Master Gardener Program

In general, the healthier you keep the lawn through proper fertilization, mowing and watering, the less problems you will have with broad leaf weeds. However, even the best cared for lawns are occasionally invaded by broadleaf weeds and require more than just preventative lawn care.

Generally hand pulling is adequate to control the few rogue weeds, but too often we are not that vigilant and those few weeds turn into many. When this happens post emergent chemicals are probably one of your best control options.

Now comes the mind numbing choices of which product to use and what weeds will it control. Generally, you will find a variety of chemicals that are offered singularly or in combinations. The most readily offered chemicals are 2,4- D, 2,4-DP, MCPP, and dicamba. Combinations of the above-mentioned herbicides are very common and these combination products allow for the control of a broader range of weed problems than single herbicides. In addition, some combinations may allow for the control of certain weed species that cannot be controlled easily by the individual components alone.

Here are some basic precautions:

  1. Ornamental plants, trees, shrubs, and vegetables can be susceptible to these chemicals. Do not spray around homes and gardens when there is a wind. Even a slight breeze is likely to carry spray droplets to susceptible ornamental and garden plants. Ester formulations (even low volatile-type) are volatile and are therefore more likely to injure nearby ornamentals, vegetables, etc.

  2. Dicamba is included in many herbicide combination products and also in some weed and feed (fertilizer-herbicide) combinations. This and other broadleaf herbicides move readily in some soil types and can be absorbed by plant roots. Therefore, products containing dicamba in particular should not be used near the drip-line of trees or near sensitive ornamentals where it can be absorbed by roots.

  3. Do not use herbicides on newly seeded lawns. Wait until the new lawn has been mowed at least three times before treating (usually about 6-8 weeks after seedling emergence).

  4. Most herbicides are safe for established tall fescue, Kentucky bluegrass, fine-leaf fescues (i.e., creeping red, hard, Chewings and blue sheep), bermudagrass and zoysiagrass lawns. All herbicides have the potential to cause some foliar yellowing. Do not use 2,4-D on lawns where bentgrasses or roughstalk bluegrass are considerable desirable species.

  5. Thoroughly clean sprayer to include hose and boom after using these herbicides. It is advised that one sprayer be used for lawns and another for spraying ornamentals. Do not allow spray mixtures or sprayer wash solutions to spill or leak onto areas where they can be taken up by foliage or roots of trees or ornamentals.

  6. Keep herbicide containers closed, properly labeled, and safely stored.

Always keep a pesticide in its original container.

CAUTION: Most herbicides are relatively safe to humans and pets when handled and applied carefully. Greatest care must be taken during the mixing of concentrates. Applicators should wear rubber gloves and boots, long sleeve shirts, long pants and eye protection. Avoid prolonged or repeated contact with skin, and be sure to wash thoroughly after using them. Store away from children, animals, fresh produce and other food products. It is best not to allow people or pets onto treated sites until the herbicide has dried on the leaves. Always read the herbicide label.

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