Hefner, M. 2019, Weed Management, Extension | University of Nevada, Reno. IP

Weed Management

As with all pest management, it is essential to identify the pest before taking action. Submit fresh plant samples to the University of Nevada Cooperative Extension or Nevada Department of Agriculture. Weeds are easiest to identify when they are flowering. Place the sample in a bag to avoid spreading seeds.

Most effective weed management plans include several control strategies. Weed control can be divided into five separate categories.


Prevention

Prevention includes using certified weed-free seed, hay and fill materials, or using transplants, amendments and mulches that are known to be weed-free. Cleaning vehicles and equipment to prevent the spread of weed seed and weed plant parts from one area to another is another prevention tactic. Prevention also includes removing weeds before they can form seed heads or spread by other methods. It is more difficult to prevent weed seeds from blowing in from an adjoining property.

photo of a tire with a puncturevine seed attached to it

Puncturevine seeds stick to bicycle tires and spread to new areas.
Clean seeds off after traveling through an infested area to reduce future problems.

Photo credit: University of Nevada, Reno Extension


Cultural controls

Cultural controls are management practices that reduce the incidence of weed infestations. Cultural controls include using proper planting times and planting rates, planting companion crops, mulching, managing fertilization and irrigation to favor desired plants rather than weeds, rotating crops and planting cover crops.


Mechanical/Physical controls

These controls physically disrupt the weed, including hand-pulling, hoeing, mowing, tilling, flooding, etc.

Photo of a person in a garden removing weeds with a shovel

Hand-removal of weeds is a time-honored practice that works well for many weeds.

Photo credit: University of Nevada, Reno Extension


Biological controls

Biological control is the use of a living organism to manage pests. This method rarely results in complete eradication of weeds. The most common biological controls for weed management include livestock and insects. Success depends upon selectivity, reproduction, adaptation, and ability of the organism to reach a high level of effectiveness. Some examples: the saltcedar leaf-eating beetle, Dyers woad rust fungus, grass carp, livestock that feed on weeds, etc.

Photo of a cup with samples of weeds

Hand-removal of weeds is a time-honored practice that works well for many weeds.

Photo credit: University of Nevada, Reno Extension


Chemical controls

Chemical control involves the use of pesticides to manage pests. Pesticides that control weeds are called herbicides. Many herbicides are available. Read the product label carefully and know how they are used and how they work before you apply them.

  • Selective herbicides: Chemicals that kill specific types of plants, such as grass plants or broadleaf plants.
  • Nonselective herbicides: Chemicals that kill all types of plants. A common example is glyphosate, the active ingredient in Roundup and many other herbicides.
  • Contact herbicides: Chemicals that kill the plant only where the chemical touches it. To be effective, the entire plant must be thoroughly covered with the product. They are quick-acting and useful in controlling annuals, biennials and seedling perennials.
  • Systemic herbicides: Chemicals that are absorbed through the leaves or roots and move freely throughout the plant. Application to part of the plant will kill the entire plant. Systemic herbicides are effective against most plants and are recommended for perennials. They take time to be effective, and may be soil- or foliage-applied.
  • Soil-applied materials may be selective or nonselective, depending upon the material and the rate of application.

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Also of Interest:

 
Protecting Pollinators/ Protegiendo a los Polinizadores
This bilingual (Spanish and English) publication describes how to protect pollinators during a pesticide application. It also describes native bees and provides additional resources for information. This is one of a series of 10 Pesticide Use and Safety/ Uso y Seguridad de Pestic...
Hefner, M., Kratsch, H., Fisher, J. and Schaerer, M.F. 2020, University of Nevada, Reno Extension Fact Sheet FS-20-10
mowing lawn
Certified Nursery Workers (2019)
A list of certified Nursery Workers from the 2019 Green Industry Training program.
Fisher, J. 2019, Extension website
Insect Management
Applying IPM strategies: Insect control can be split into these five separate categories.
Hefner, M. 2019, Extension | University of Nevada, Reno. IP
Tips for Lower-risk Pest Control
Products are available that have less risk to the user and others. Select these whenever appropriate.
Hefner, M. 2019, Extension | University of Nevada, Reno, IP
Tips for Managing Insect Pests in the Landscape
Did you know that 99% of all insects are not harmful to you or your landscape? Determine which insects are helpful and head head off insect pests by following these tips:
Hefner, M. 2019, Extension | University of Nevada, Reno. IP.
 

Associated Programs

ladybug larva eating aphids on a pepper plant

Integrated Pest Management

Integrated Pest Management program is a long-term management strategy that uses a combination of tactics to reduce pests to tolerable levels with potentially lower costs for the pest manager and minimal effect on the environment.

 

Extension Director's Office | On the campus of University of Nevada, Reno