Marestail/Horseweed in Grape Plantings
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Marestail/Horseweed (Conyza canadensis) is an annual to biennial weed that can reach heights of 3 to 6 feet. Stems are nearly completely covered with alternate ascending leaves approximately 2½ inches long by ½ inch wide. Leaves may even appear whorled due to their dense arrangement. Seeds germinate throughout spring, summer, and autumn. Plants mature and set seed the same year. Late-season plants overwinter in the rosette stage. One plant may release 20,000 seeds that disperse easily by wind.
Marestail growth habit.
(Photo: Rober Videki, Coronicum Kft., Bugwood.org)
Marestail growth habit.
(Photo: John Strang, University of Kentucky)
Marestail flowers.
(Photo: Mary Ellen (Mel) Hart, Bugwood.org)
Management:
- Cultivate to destroy young plants.
- Apply preemergent herbicides to prevent seed germination.
- Use burn-down herbicides during seedling or rosette stages.
- Glyphosate-resistant marestail is becoming more common. Herbicide-resistant populations should be confirmed by a county Extension agent or the Weed Science Society of America.
