Dogfennel (Eupatorium capillifolium) is a perennial weed common to turf, roadsides and container plants. Depending on the management practices for the site, dogfennel can grow to be a very tall plant (exceeding 3 feet in height), or may reach maturity as a short plant (less than 6 inches). The finely dissected leaves of the plant make it easy to identify, and when crushed, the leaves and stems have a very distinct odor that is slightly sour and musty. The stems of dogfennel are soft and easily broken when young, but become very tough and woody as it ages. In addition, the stems are very conspicuously hairy, especially when young, but leaves are always hairless. Dogfennel could be confused with several other common turf weeds, including horseweed and mugwort. However, mugwort has very distinctive white wooly hairs on the underside of each leaf, and horseweed has elongated leaves with few to no serrations, and dogfennel has highly divided leaves.

Figure 1. Dogfennel.

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Figure 1. Dogfennel.

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Perennial broadleaf turf weeds are capable of living more than two years. They thrive in weak, thin turf; golf fairways and roughs; home lawns; playfields; and industrial grounds. Proper turf maintenance is the key to control of this weed. First, select adapted turfgrass cultivars for your area and then properly fertilize, mow, and water to encourage dense growth.

• GROWTH SEASON / LIFE CYCLE
  • perennial weed
• GROWTH HABIT
  • upright, may reach more than 6 feet (2 m) in height
• LEAFLET NUMBER
  • one
• LEAF MARGIN
  • deeply lobed, with serrated edges
• LEAF HAIRS
  • none
• LEAF VENATION
  • pinnate
• LEAF ARRANGEMENT
  • lower leaves may be opposite, but upper leaves are alternate
• ROOT TYPE
  • fibrous
• FLOWER COLOR
  • inconspicuous, greenish-white