Managing Invasive Plants: Concepts, Principles, and Practices link

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MANAGING INVASIVE PLANTS: Concepts, Principles, and Practices

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Management Methods: Chemical Methods

Review, Resources, & References


Test Your Knowledge

Review the key points and then test your knowledge of chemical methods by taking a quiz.

Key Points


Herbicides can be very efficient and effective in suppressing or killing unwanted plants, particularly when used in combination with other management methods. They should be used judiciously, safely, and in a way that minimizes effects on nontarget resources.


IPM promotes using pesticides judiciously and in combination with other methods in a way that increases effectiveness and minimizes harm.

3. HERBICIDEs are classified to support understanding

Given the considerable number of herbicides available, different ways of classifying herbicides have been developed to distinguish among them. Herbicide classification also provides a means of understanding general similarities among herbicides. A working knowledge of herbicide classification is essential in selecting herbicides, diagnosing herbicide injury symptoms, managing herbicide resistance, and predicting herbicide interactions in the environment.


All of the interactions between an herbicide and a plant that occur from application to the final effect are referred to as the mode of action. Understanding the mode of action is essential in selecting the proper herbicide, diagnosing herbicide injury symptoms, preventing herbicide resistance problems, and avoiding nontarget environmental impacts.


The herbicide mechanism of action is the specific biochemical or biophysical process in the plant that is affected by the herbicide. Using herbicides with different mechanisms of action, or combining them with other control methods, can reduce the risk of developing herbicide-resistant populations.


Herbicides can be an effective tool against undesirable plant species but can have unintended adverse effects. Benefits must be weighed against the potential for exposure and impacts to human health, nontarget organisms, and the environment. Risks are always present with any herbicide use, but misuse of herbicides can increase these risks.


The Federal Insecticide, Fungicide, and Rodenticide Act governs registration, distribution, sale, and use of herbicides nationwide. The US Department of Interior Integrated Pest Management Policy (517 DM 1), the USFWS Pest Management Policy and Responsibilities (30 AM 12), and the USFWS Refuge Manual (7 RM 14), provide further guidance for herbicide use on USFWS lands.


The effectiveness of herbicides is a function of several biotic, abiotic, and procedural factors. Understanding these factors can help applicators select safe and effective herbicides for target species and conditions, properly handle herbicides, minimize impacts to nontarget resources, and determine the most effective time, rate, and technique for herbicide application.


Monitoring activities should be designed to detect changes not only in target species populations, but also in desirable plant species, as well as adverse effects on other nontarget organisms, and soil and water resources.


When used alone, herbicides can provide rapid and effective control of target plant populations. Integrating herbicides with other management methods can enhance the effectiveness of each method and is more likely to achieve sustainable, long term solutions.

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Western Society of Weed Science - Crop Technology Lessons

The Nature Conservancy - Weed Control Methods Handbook

Herbicide Handbook of the Weed Science Society of America (9th Edition)

University of Florida - Training Manual for Aquatic Herbicide Applicators

Fundamentals of Weed Science (1999)

Zimdahl RL. 1999. Fundamentals of Weed Science. Second edition. San Diego (CA): Academic Press. 556 p.

Weed Ecology: Implications for Management (1997)

Radosevich S, Holt J, Ghersa C. 1997. Weed Ecology: Implications for Management. Second edition. New York: John Wiley and Sons, Inc. 589 p.

US Army Corps of Engineers - Noxious and Nuisance Plant Management Information System

Weed Science: Principles and Practices (2002)

Monaco TJ, Ashton FM, Weller SC. 2002. Weed Science: Principles and Practices. Fourth edition. New York: John Wiley and Sons. 672 p.

Policy and Regulations

US Fish and Wildlife Service - Environmental Quality Program - Pesticides

US Environmental Protection Agency - Regulating Pesticide

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August 21, 2008