This research objective is to determine the timing of horseweed germination across various sites in the Mid-Atlantic region, to see if patterns are shifting. Seedlings emerge in all but winter months. Previous research found that most of the population emerged in the fall, and could be controlled then. However, farmer observations indicate more horseweed may be emerging in the spring. Understanding the current emergence period for horseweed will allow farmers to select the best burndown approach. Fall-emerging plants need to be controlled in fall or early spring. However, patterns have changed, either an effective residual herbicide should be recommend or the burndown should be delayed to late spring.

Key Benefactors:
farmers, agronomists, Extension agents