Weed ID

Giant miscanthus (Miscanthus x giganteus) is a perennial nonnative grass hybrid that is being investigated as an alternative crop in Maryland. Although the invasive potential of this species appears to be low, there is little information about how to manage giant miscanthus should it become weedy, or should another crop be desired following miscanthus production. Therefore, studies were conducted to evaluate control methods for giant miscanthus in two agronomic settings (discing and no-till) as well as herbicide options for riparian settings. Results indicated that multiple herbicide treatments or mowing followed by herbicide treatments over successive years would be needed to eliminate giant miscanthus. Authors: Kurt Vollmer and Ellie Rogers; Considerations for Terminating Giant Miscanthus on Maryland Farms (FS-2023-0685).

Palmer amaranth, Amaranthus palmeri, is a new invasive weed in the pigweed family that has become a major challenge for farmers across the U.S. for much of the last decade. Native to the Sonora Desert of Arizona and Northern Mexico, Palmer amaranth is well adapted to the hot Maryland summers. It was first discovered in Maryland during the mid-twentieth century, but the presence of herbicide resistant Palmer amaranth was not confirmed until 2014. Since then it has spread to most regions of the state including Eastern, Southern, and Western Maryland. The spread of Palmer amaranth has been hastened by the movement of contaminated equipment, feed, and seed from infested areas.

Pigweeds are annual weeds that can cause significant problems for Maryland farmers. Palmer amaranth and waterhemp are two pigweeds that are especially troublesome, and have been designated as noxious weeds by the Maryland Department of Agriculture. Therefore, it is required that these two species be actively managed to prevent their spread and resulting negative impacts on Maryland agriculture. To the untrained eye, Palmer amaranth and waterhemp can appear similar to each other and to other pigweed species. However they can be easily distinguished from one another by looking at some key botanical characteristics. Becoming familiar with these species allows for earlier detection, and as a result, improved management practices. Authors: Kurt Vollmer, Ph.D., and Ben Beale; Title: Keys to Identifying Palmer Amaranth and Waterhemp (FS-2023-0653)

This hand-held guide provides information on how to identify and differentiate common pigweed species in Maryland including: Palmer amaranth, Spiny amaranth, waterhemp, and redroot/smooth pigweed. Authors: Kurt Vollmer and Ben Beale; Title: A Guide for Identifying Pigweed Species Commonly Found in Maryland (EB-2023-0654)