To be classified as a South Dakota state noxious weed, the weed must be a perennial, spread by underground parts as well as seed. They are difficult to control with normal management operations, capable of decreasing crop and livestock production. A noxious weed decreases land value, and generally impedes the welfare of the people of the state. All of South Dakota’s noxious weeds have been imported and most have been introduced as a crop seed contaminant.

Noxious weeds threaten wildlife by displacing native forage and nesting habitat. They reduce forage and row crop productivity. The aggressive growth of noxious weeds can dramatically reduce establishment and growth of new tree plantings and threaten native endangered plant species. These native plants may be future sources of genetic material or medicines. The increase in soil erosion from noxious weed infestations not only reduces the productivity of the land but increases sedimentation in lakes and streams reducing the quality of fish habitat. Outdoor recreation can be seriously hampered by noxious weeds. These very invasive weeds are causing alarming economic losses to the state and require a concerted effort to bring them under control.

When developing a weed management strategy it is critical to consider all available resources and tools. The integrated utilization of the various weed management options should focus on the most economical and effective control of noxious weeds. Anything that weakens the weed, prevents spreading, or prevents seed production can be a valuable tool. The options or tools that are integrated into an effective weed management plan may be biological, cultural, or chemical.

Insects are the primary introduced biological control tool being used against noxious weeds. However it may take a few years for the insect population to multiply to a sufficient level for effective weed control. Therefore the perimeter of infestations should be chemically controlled to prevent the spread of the weed while the insects are multiplying.

Pathogens are disease causing organisms including fungi, bacteria, viruses, etc. This area of weed control warrants more exploration.

Grazing animals are being used successfully to help suppress weed growth and seed development.

Replanting competitive plants in areas where noxious weeds have been controlled can help reduce re-establishment of the weeds from residual seed. Replanting also helps reduce soil erosion.

Grazing management is a valuable tool for controlling weed establishment and growth. Overgrazing will favor the growth of weeds while taller grasses shade the soil and provide competition against weeds.

Forest canopy management provides a balance of large tree and understory plants to compete with noxious weeds for light, water, and nutrients.

Prevention is the best way to avoid having a problem. Preventing infestation is far more economical than trying to control an established noxious weed problem. Most noxious weeds have entered the United States as crop seed contaminants. Planting Certified seed provides cheap insurance against weed introduction. Utilization of certified weed free forage can aid in preventing weed introductions on range and forest lands. Cleaning equipment prior to moving to a new location reduces weed seed movement.

Mowing at the right stage of plant development can prevent flowering and subsequent seed production.

Cultivation by machine or hand, or even hand pulling can control weeds.

Fire has been used for disease and weed seed control for many years in the grass seed industry.

Effectiveness for control of a weed can vary considerably between herbicides. When selecting a herbicide, be sure that the target weed and intended use is on the label. A herbicide efficacy chart can provide valuable information when selecting a chemical.

Least environmental impact chemicals should be selected that will target the weed with little or no effect to non-target organisms or water quality. Select a chemical that will do an effective job and will not persist but will break down rapidly in the environment.

Economics plays a part in selecting a practical herbicide. Just because an herbicide is expensive doesn’t mean that it couldn’t be more economical. Number of treatments may be reduced if effectiveness is better for the specific weed species. Personal and environmental safety and the rate of chemical per acre must also be considered.

General application may be required if a large area is infested with noxious weed(s).

Spot treatments are used when the noxious weed(s) infestation is sporadic or in small areas. It is recommended that the perimeter of the weed patch is sprayed to control small, undetected seedlings.

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