Herbicide Alternatives Research - Executive Office of Transportation

2.3.1 Integrated Management for Roadside Weed Control
Integrated Vegetation Management (IVM). Roadside vegetation management takes many
approaches including traditional application of nonselective and selective herbicides, intensive
mowing, brushing, and hand weeding as well as a preventive maintenance approach commonly
labeled as Integrated Vegetation Management (IVM) or Integrated Roadside Vegetation
Management (IRVM). The approach of IVM is similar to that of Integrated Pest Management
(IPM), a systematic strategy in pest management that has been adapted widely in production
agriculture and in landscape management (Buhler, 2002; Cook, 2000; Elmore, 1996; Jacobsen,
1997; Prokopy, 1994).
In theory, IVM employs a variety of approaches in the management of roadside vegetation. As
with IPM, IVM methods include cultural, mechanical, biological, and chemical strategies,
including chemical herbicides.
With respect to roadside vegetation management, examples of cultural practices include the
promotion of desirable plant species to reduce opportunities for weed species to become
established or grow with vigor and mowing high (4 to 6 inches) to clip weeds, while maintaining
desirable species below the mowing level. Mechanical practices include mowing, weeding,
grubbing, and cutting of woody species. Biological approaches include release of predatory
species and the planting of dense-growing ground covers to exclude weeds. Chemical methods
may include application of growth regulators and conventional or alternative herbicides.
Henderson (2000) reported considerable variation in knowledge of, definition of, and practice of
IVM among state DOTs. A detailed description of the principles, procedures, and practical
application of IVM are presented in Integrated Vegetation Management for Roadsides (Daar and
King, 1997) for the Washington State DOT and in Best Practices Handbook on Roadside
Vegetation Management (Johnson, 2000) for Minnesota. Some of the topics discussed include:
definitions of IVM; integrating IVM into the maintenance programs; monitoring the programs;
selecting; applying; and evaluating treatments, education and outreach.
Roadside Vegetation Management Zones. Researchers at The Pennsylvania State University
(Gover et al., 2000) describe the concept of roadside Vegetation Management Zones. Similar
vegetation zones have been described by other investigators (Daar and King, 1997; Johnson,
2000; Nowak 2004). Each zone is defined on the basis of target vegetation and the intensity of
maintenance needed. The zones as described by Gover et al. (2000) are primarily for limitedaccess
highways but also relate to maintenance along free-access roadways. Most states use a
similar concept although the details vary. The management zones as defined by Gover et al.
(2000) are:
Non-Selective Zone (Zone 1). This area is immediately adjacent to a roadway and needs to be
kept essentially free of vegetation to facilitate flow of water off the roadway and to maintain
visibility. This zone includes the area beneath guard rails.
Safety Clear Zone (Zone 2). This zone may extend up to a distance of 30 feet from the road edge.
Typically, this area is seeded to grasses or other low growing vegetation and is kept free of
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