12 sussex county stream

A stream in Sussex County (photo by Charlie & Barbara Newlon)

(by Steve Kallesser, CF, vice chair)

Given increased attention on control of exotic invasive plants and other competing understory vegetation, use of herbicides appears to be increasing in New Jersey’s and adjoining states’ forests.  Studies on Best Management Practices have found that by leaving a 50-foot no-spray Streamside Management Zone (SMZ) on regeneration areas receiving significant herbicide treatments can reduce herbicide concentrations in adjacent streams by five-fold.  A recent study published in Forest Science looked at two different management regimes, each using 50-foot no-spray SMZ’s.

The study examined use of imazapyr (marketed as Arsenal), hexazinone (Velpar), and sulfometuron methyl (Oust), all of which are broadleaf herbicides. In the study, these were only found in streams following storm events and in many cases were only at concentrations known to affect the most sensitive organisms (certain algae) for less than 12 hours.  Given the length of time needed to create a response in sensitive organisms (2-21 days of exposure), and the amount of herbicide necessary to affect those organisms, the study concluded that contemporary Best Management Practices that include 50-foot no-spray SMZ’s along intensive treatment areas are sufficient to prevent chronic exposure of aquatic biota and protect water quality.  Smaller buffers may be adequate for less-intensive applications.

To read the study click here.