by Steve Kallesser, Division Chair

Herbicide use in the forest is on the uptick as private and public landowners get serious about controlling exotic invasive plants. The most common type of herbicide treatment is spot treatment of individual plants, usually by an applicator who is using a backpack sprayer. The basal bark method and cut stump method are also used as a spot treatment, as is the hack-and-squirt method (especially for ailanthus control). At the more intensive end of the scale are some contractors who mow heavy infestations of non-native invasive brush and apply herbicide to the cut stumps as they go. It is not known if any other more intense spraying, ground-based broadcast spraying, or aerial spraying of herbicides takes place in New Jersey, or is envisioned to take place in the future.

walking pic

Should buffers between streams and aerial spray zones be wider when aircraft are flying at higher altitudes? (photo by Patricia Kallesser)

Other pesticides in forested settings have largely fallen out of favor in New Jersey, in favor of biological controls or sanitation/treatment cuts. One exception to this is the treatment of gypsy moths during peak infestations. Ground-based and aerial spraying do occur, particularly along public road corridors and intensively-used forested recreation areas.

The 1995 BMP manual makes no real differentiation between SMZ and non-SMZ riparian/wetland buffer areas, other to state that machinery-mounted sprayers should not operate within SMZ’s. Aerial application of pesticides in not allowed within 50’ of streams and open waters. This width was taken from EPA guidance, at the time. That guidance does not appear to have changed.

Of note, Oregon has a 60’ buffer for aerial spraying. The federal EPA also has a 300’ buffer for spraying certain pesticides near certain waterways with endangered salmon in Washington, Oregon, and California, as a result of a settlement of a lawsuit. (Ground-based applications have a 60’ buffer.) It is also worth noting that the 50’ default EPA aerial spraying width is based on an aircraft spraying height of 10’. Clearly this is not the case for gypsy moth spraying of mid-successional oak forests, where the spraying height may be 90’ to 110’.

Of studies regarding herbicides and stream quality, much of the focus has centered on proper timing of herbicide application vis-à-vis precipitation events. Other research has looked at the need to anticipate seeps that appear at the toe-of-slope above a stream after an adjacent regeneration harvest (as well as breakthroughs discussed in another section) as a vector for chemical delivery into a stream. Several of these studies have been reviewed in The Cruiser over the past two years, and most of them have been based on high-intensity management in industrial forests.