Forestry herbicides in the United States: an overview

• Published in: Wildlife Society bulletin 2004-12, Vol.32 (4), p.1020-1027
• Main Authors: Shepard, James P., Creighton, Jerre, Duzan, Howard
• Format: Article
• Language: English
• Subjects: aerial application; Commercial forests; Environmental agencies; Forest habitats; Forest management; Forest service; Forestry; Freshwater; herbicide; Herbicides; Pesticides; silviculture; social concerns; Social conditions & trends; SPECIAL COVERAGE: HERBICIDES AND FOREST BIODIVERSITY; Toxicity; Weed control; Wildlife; Wildlife habitats; Wildlife management
• ISSN: 0091-7648; 1938-5463
• DOI: 10.2193/0091-7648(2004)032[1020:FHITUS]2.0.CO;2

Herbicides are used in forestry to manage tree-species composition, reduce competition from shrubs and herbaceous vegetation, manipulate wildlife habitat, and control invasive exotics. There are no national statistics on extent of forestry herbicide use. A survey of 13 forest products companies found that 51 distinct applications of 1–3 herbicides were used and that 11 applications (with 6 active ingredients) accounted for 90% of the area reported treated. Reported rates were always lower than maximum labeled rate, and average rates ranged from 10–42% of the labeled maxima. Herbicides were used on 74,464 hectares in the National Forest System (including rangeland) in 2001. Another survey of forestry herbicide use by all ownerships in the southern United States in 2002 reported 985,237 hectares treated. Public concerns over use of herbicides in forests include toxicity to humans, pets, livestock, and wildlife and effects of herbicides on wildlife habitat. The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) provides a comprehensive system of toxicity testing and regulates sale and use of herbicides. However, there are concerns about FIFRA testing: use of a small number of sentinel species, testing only active herbicide ingredients, and not testing the mixtures of ≥2 herbicides commonly used in forestry. Recent litigation suggests that aerial application of pesticides (including herbicides) is a point-source discharge of pollutants into waters of the United States and thus requires a Clean Water Act (CWA) permit. These lawsuits have created confusion about how 2 federal statutes (FIFRA and CWA) relate with regard to pesticides, and new policy clarification is being developed. Other litigation has initiated a process to improve consultation among federal agencies regarding potential for pesticides to affect threatened and endangered species. In summary, herbicides are vital for commercial timber management and have applications for managing wild-life habitat. Federal regulations and water-quality monitoring indicate that use of herbicides in forestry constitutes low risk to humans and wildlife.