Ken Mc Nabb
Auburn University
July 2014
Herbicides are routinely used in forest management throughout the United States under a variety of land management objectives and situations. The following are several key factors to keep in mind when contemplating the use of herbicides in forestry situations.
1. READ THE LABEL
Herbicides are pesticides and as such are regulated by federal and state law.
Their purchase, storage, use, and transport are controlled by these regulations.
The most important consideration for landowners is the content of the herbicide
label. The label is a legal contract between the manufacturer and the user. It
provides specific performance guarantees by the product when applied as
specified on the label. It is the user’s responsibility to ensure the product is
used in an appropriate and legal manner. Read the label!
2. EMPHASIS ON PINE SILVICULTURE
For the great majority of cases in the southeastern United States, forestry
herbicides are used for the culture of pines - loblolly, slash, longleaf, and
shortleaf. While herbicides can and are used for the cultivation of hardwood
species, most herbicide applications in the Southeast are made to reduce or
eliminate herbaceous weeds and hardwood tree competition in pine stands.
3. WHEN MIGHT HERBICIDES BE APPLIED
There are three major application situations for forestry herbicides: (a) site
preparation prior to planting, (b) herbaceous weed control during the first and
possibly second year after planting, and (c) release. The term “release” will
refer to a situation where the primary stand of crop trees is established, but
woody plant weed species are targeted for control. The most common release
treatments are made during the first 4-6 years after plantation establishment,
but may in fact be executed anytime during the rotation, particularly just prior
to a thinning or final harvest.
4. SITE FACTORS
Developing a herbicide “prescription” is a complex process that must incorporate
a number of factors including soil type, topography, vegetation, species and
condition of the crop tree, character of adjacent properties, and special
features such as water courses, and unique conservation areas.
5. THERE ARE MANY PRODUCTS LABELED FOR FORESTRY
There are several legally available herbicide products that may be used in
forest vegetation management, although many of them have the same active
ingredient. The product formulations change to better match different
application situations. Some of the more common product names are Accord,
Arsenal, 2, 4-D, Escort, Garlon, Oust, Tordon, and Velpar.
6. HERBICIDES VARY
Understanding herbicide characteristics are an essential component of developing
the vegetation management prescription. Herbicides vary in their pathway of
plant absorption, leaching potential, degree of volatilization, their
effectiveness against certain plant species, and other important
characteristics. A product that might be appropriate in one situation, can
easily be ineffective in another situation.
7. GETTING THE PRODUCT INTO THE PLANT
There are a great many techniques to apply herbicides - everything from a
helicopter to a hand axe, from a farm tractor to a specially rigged ATV. The
appropriate application technique must be matched with the product label, the
site, and the intended target
8. A JOB FOR A PROFESSIONAL
Many things need to be coordinated correctly to obtain a cost-effective
herbicide application. It is truly a job for a trained and experienced
professional. Landowners should rely on either a professional forester or a
licensed professional applicator to develop the prescription and execute the
application. County foresters of the Alabama Forestry Commission or Alabama
Cooperative Extension System personnel should also be able to help you locate
professional assistance.
SOURCES OF ADDITIONAL INFORMATION ON FORESTRY HERBICIDES
“Chapter 12: Forest Vegetation Management by Dwight Lauer,” in Managing Forests on Private Lands in Alabama and the Southeast by D. Gjerstad, K. Mc Nabb, and R. Oates. 2010. Sweetwater Press. May be purchased from the Alabama Forestry Foundation, Montgomery, Alabama.
Crop Data Management Systems (CDMS) can be searched for Herbicide Labels and Material Safety Data Sheet (MDSs) http://www.cdms.net/manuf/.
National Pesticide Information Center contains general, technical and regulatory information about pesticides including herbicides. Information can be obtained directly from the NPI in several languages http://npic.orst.edu/index.html.
McNabb, K. 1997. Environmental Safety of Forestry Herbicides. ANR-0846. Alabama Cooperative Extension System, Auburn University, Al., 6 pp. http://www.aces.edu/pubs/docs/A/ANR-0846/ANR-0846.pdf