The dicamba drift crisis continues to deepen, with worrisome coverage of the largely hidden (so far) toll of this herbicide on trees and vines, and wild landscapes.

NPR’s Dan Charles has taken an in-depth look at dicamba’s impact on some “Prized Trees” throughout the Midwest and Midsouth, including 200 year old cypress in Tennessee (see the image to the right).  While some regional variation in impacts is emerging, the damage to trees is widespread, appears to be growing worse year to year, and is already impacting large areas.

One of the most severely affected states throughout the crisis has been Arkansas.  In this piece, you can hear Charles tell the story of one Arkansas scientist who conducted extensive surveys, observing “dicamba-damaged trees in every town that he visited across the northeastern part of the state.”

Then there is this article by Harvest Public Media from fall 2017 which focuses on damaged oak trees in Iowa, Illinois and Tennessee.  In Iowa alone in 2017, there were over 1,000 complaints filed at the State Department of Natural Resources about oak tree damage from pesticides, and dicamba is considered a likely culprit in many cases.

Like the 200 year-old Tennessee cypress trees, dicamba is injuring massive, historic oaks.  As an example, the story describes damage to ancient oaks at Funk’s Grove nature preserve near Bloomington, Illinois (century-old trees are a rarity in the middle of the country). Several other natural areas in the state are also affected.

Scientists are closely tracking dicamba damage to crops, and the EPA is struggling over the decision whether to extend beyond 2018 the registration of post-emergent uses of dicamba. At the end of the day, EPA is bound by law to “balance” the risks and benefits stemming from continued spraying of dicamba on GMO, herbicide-resistant soybeans and cotton.

Doing so requires up-to-date and accurate information on both dicamba uses and alternatives (the guts of a herbicide “benefits” assessment), as well as the adverse impacts of dicamba on non-target crops, trees, vines, and forests, and human health.

Expanded effort is clearly needed to track dicamba drift damage away from the farms and at the landscape scale, and not just field by field. Hard data and more research, especially on trees and natural vegetation, is going to be essential in order to meaningfully estimate “benefits” and “risks,” and find the elusive point where the former assuredly outweighs the later.

Sources:

Dan Charles, “A Drifting Weedkiller Puts Prized Trees At Risk,” NPR,  September 27, 2018.

Jonathan Hettinger, “Weed Killer Dicamba Eyed In Oak Tree Damage Across Iowa, Illinois And Tennessee,” Harvest Public Media, October 11, 2017.