Herbicide treatments are often used to reduce competition between undesirable vegetation and planted or naturally established tree seedlings.
Pesticides specific for plant control are called herbicides. Today’s herbicides are a safe and effective method for controlling interfering plants. In forest management, herbicides reduce competition between undesirable vegetation and valuable crop trees as well as aid in regeneration establishment, enhance wildlife habitat, control non-native plants, and facilitate road maintenance. Herbicide applications are a part of any IVM program.
No single herbicide, rate, or application method works for all vegetation management needs. Each situation requires advanced assessment to ensure the safest, most efficient, and cost-effective chemical control program is chosen. Soil type, plant species, density, and size all affect the herbicide prescription. Additional factors such as time of year, and weather conditions are important because they affect plant growth, herbicide uptake, and translocation.
For treating large extensive areas broadcast treatments using helicopters or tractor mounted equipment may be necessary. These treatments are generally done as non-selective applications. However, herbicide application methods are also available to selectively target individual plant species with little or no impact to non-target plants. With selective applications, the herbicide is applied directly to the target plants. These methods include directed foliar sprays, cut surface, and basal bark applications. For detailed herbicide application methods consult the Penn State Cooperative Extension Herbicides and Forest Vegetation Management publication.
Herbicide Treatment Guidelines
Many interfering and competing plants are perennials, with extensive root systems. Herbicide treatments often offer the best means of eradication because they can control root systems without baring soil to erosion or re-invasion. For effective herbicide treatments follow these guidelines:
- Use herbicide that is most effective at controlling target species.
- Use herbicide at the lowest labeled rate that will give optimum control.
- Follow prescribed application methods on label.
- Apply herbicide at optimum time of year.
- Follow all label precautions.
- Be patient, allow time for herbicide to work. Results may not be evident until the following growing season.
Skidder mounted mist blowers provide a non-selective understory treatment neccessary to control interfering vegetation when trying to naturally establish hardwood seedling regeneration.
(Revised from J. Miller, Nonnative Invasive Plants of Southern Forests: A Field Guide for Identification and Control, U.S. Forest Service Southern Research Station, 2003.)
Herbicides commonly used in forestry are available under a variety of trade names. Therefore, it is best to become familiar with common names (active ingredients).