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Biennial Wormwood

Biennial Wormwood (Artemisia biennis)

This has weed has become more abundant in the last decade in the northern states and Manitoba. The plant is native to North America. Its emergence is indeterminate which greatly complicates control strategies. Emergence can begin early in the season and continue into July. It has tolerance to many chemistries including Beyond, Express, Aim, Treflan, Sonalan, and Prowl. According to NDSU weed scientists, Biennial wormwood is often misidentified as common ragweed. To insure proper identity, NDSU scientists describe Biennial wormwood leaves as having sharp edges and being hairless, whereas common ragweed leaves have smooth and round edges and are hairy.

Control Strategies 1. Pre-emergent burn down is necessary using any of the labeled products but recognizing that the weed has developed tolerance to Aim 2. Spartan has good to excellent control 3. Beyond¹ and Express² are considered as ‘poor' control. Plus there is the issue of tolerance 4. Between row cultivation or hooded sprayer herbicide application

Links of Interest

Kansas State University Dept of Agronomy NDSU Crop Production and Marketing South Dakota Pest Management Guides (sdstate.edu) National Bird-Feeding Society

Footnotes

(1) Beyond herbicide is specific to CLEARFIELD® hybrids only. Clearfield hybrids have been developed with a resistant gene to Beyond herbicide. Applying Beyond herbicide on non-Clearfield hybrids will result in extensive damage. (2) Express herbicide is specific to ExpressSun® hybrids only. ExpressSun hybrids have been developed with a resistant gene to Express herbicide. Applying Express herbicide on non-ExpressSun hybrids will result in extensive damage. Glyphosate and Aim are labeled for between row hooded sprayer applications.