Publication describes results from study of herbicide best management practices

Forest managers often use herbicides to temporarily suppress competing plants in intensively managed forests. When used, herbicides typically are applied one to three times during an even-aged rotation. Foresters have developed best management practices to minimize movement of herbicides off sites where they are applied.  For example, streamside management zones are retained to minimize movement of herbicides into adjacent streams and to accomplish other environmental objectives.

A paper recently published in Forest Science reports on herbicide residue concentrations in streams after operational applications to adjacent loblolly pine plantations established with full implementation of modern forestry best management practices. The paper was authored by Lynsey Scarbrough and Rhett Jackson of the University of Georgia, Samantha Marchman of Plum Creek Timber Company, Ginny Allen and Jeff Louch of NCASI, and Masato Miwa of Fukuoka University. The authors conclude that their results “agree with previous studies of instream herbicide concentrations after silvicultural application and indicate that transport of these chemicals to streams is low after proper application and use of modern forestry BMPs.”

The abstract for the paper follows.

“Herbicides are an important tool for managing competitive vegetation in pine silviculture, and forestry best management practices (BMPs) were designed partly to minimize the movement of overland flow and dissolved herbicides into adjacent streams. We measured herbicide concentrations in streams before and after application when all modern forestry BMPs were applied to silvicultural operations. Imazapyr, hexazinone, and sulfometuron methyl were applied operationally to pine plantations covering 45 and 54% of the watershed area of two first-order streams in the Upper Coastal Plain of Georgia, USA. Herbicides in stream water were sampled and analyzed before and for several months after application. All three herbicides were detected during stormflows after application, but the highest observed concentration was 7.7 parts per billion (ppb), just a few ppb above the level of quantification. The highest concentrations occurred in the first or second stormflow event after application, and peak concentrations diminished rapidly in subsequent events. Quantifiable concentrations occurred as pulses lasting 1/2–1 day after the hydrograph peak. Herbicide concentrations were below or near the level of quantification for all baseflow samples. Our results suggest that transport of these operational silvicultural herbicides to streams is low with proper application and use of modern forestry BMPs, and these results are in concurrence with other recent studies of herbicide movement from modern forestry operations.”  

Reference 

Scarbrough, S.L., C.R. Jackson, S. Marchman, G. Allen, J. Louch, and M. Miwa. 2015. Herbicide concentrations in first-order streams after routine application for competition control in establishing pine plantations. Forest Science 61(3):604–612. http://dx.doi.org/10.5849/forsci.14-051