Description

Knawel is a winter annual which, when it first germinates, may go unnoticed because of its grasslike features. It closely resembles parsley-piert and lawn burrweed. It is a freely branched plant with spreading stems. Leaves, clasping the stem, are opposite, linear, less than 1 mm wide, and sharp-pointed. The very inconspicuous flowers are clustered in the leaf axils. They are small, green, lacking petals, and somewhat spiny to the touch.

Cultural Control

Winter annual broadleaf weeds germinate in the fall or winter and grow during any warm weather, which may occur in the winter, but otherwise remain somewhat dormant during the winter. They resume growth and produce seed in the spring and die as temperatures increase in late spring and early summer. They quickly invade thin turf areas especially where there is good soil moisture. Shade may also encourage growth. Many have a prostrate growth habit and are not affected by mowing. A dense, vigorous turf is the best way to reduce the encroachment of winter annual weeds. First, select adapted turfgrass cultivars for your area and then properly fertilize, mow, and water to encourage dense growth.

Species Data

GROWTH SEASON / LIFE CYCLE
- winter annual weed
GROWTH HABIT
- prostrate, spreading; can form low mats or clumps in established turfgrass
  Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figure 9, Figure 10
LEAFLET NUMBER
- four or more
  Figure 11, Figure 12
LEAF MARGIN
- smooth
LEAF HAIRS
- none
LEAF / LEAFLET SHAPE
- linear / oblong
  Figure 13, Figure 14, Figure 15, Figure 16, Figure 17
LEAF WIDTH
- <¹⁄₂ inch
LEAF VENATION
- parallel
LEAF ARRANGEMENT
- opposite
ROOT TYPE
- fibrous; taproot
FLOWER COLOR
- very inconspicuous green flowers
  Figure 18

Figure 1. Knawel growth habit.

Figure 2. Knawel growth habit.

Figure 3. Knawel growth habit.

Figure 4. Knawel growth habit.

Figure 5. Knawel growth habit.

Figure 6. Knawel growth habit.

Figure 7. Knawel growth habit.

Figure 8. Knawel growth habit.

Figure 9. Knawel growth habit.

Figure 10. Knawel growth habit.

Figure 11. Knawel leaflet number.

Figure 12. Knawel leaflet number.

Figure 13. Knawel leaflet shape.

Figure 14. Knawel leaflet shape.

Figure 15. Knawel leaflet shape.

Figure 16. Knawel leaflet shape.

Figure 17. Knawel leaflet shape.

Figure 18. Knawel flower color.

Author

Fred Yelverton: Extension Specialist (Turfgrass/Forage Crop Weed Mgt)
Crop & Soil Sciences

Publication date: Nov. 21, 2017

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This publication printed on: Dec. 11, 2023

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