Witch Grass
Scientific Name: Panicum capillare
Family: Grass Family (Gramineae)
General Description: Annual, reproducing only by seed.
Habitat: Witch grass is very common in fields, waste areas, roadsides, backyards, gardens and occasionally in lawns throughout southern Ontario and sporadically in northern and northwestern Ontario.
Stems
- Stems 5 - 120 cm high, erect, or spreading.
Leaves
- Leaf blades and leaf sheaths densely hairy
- The hair 2 - 3 mm long and becoming harsh and prickly as the plant matures
- Leaf sheath split (B), its margins (a) either separate or overlapping
- Ligule (b) a dense fringe of hair 1 - 2 mm (1/25 - 1/12 in.) long
- No auricles
Flowers
- Inflorescence (C) a large, loose, open, fluffy panicle with numerous, very fine branches and tiny spikelets (d) at the ends of those branches
- The much-branched panicle often wider than long and, on small - to medium-sized plants, often making up ½ to 2/3 the total height of the plant
- Mature spikelets 0.7 - 0.8 mm wide by 2.0 - 2.3 mm long florets ("seeds") 0.6 - 0.7 mm wide and 1.3 - 1.4 mm long shiny gray-brown with 5 parallel beige veins
- At maturity, the stem breaks easily below the inflorescence and the whole panicle is rolled and tumbled by the wind, dropping seed with every bounce
- Flowers from July to September
Roots and Underground Structures
- Fibrous root system
Often Confused With/ Distinguishing Features
Witch grass is often confused with Fall panicum and Proso millet. It is distinguished from Fall panicum by its densely hairy leaves and leaf sheaths, its very fine, bushy panicle and its smaller seeds; and from Proso millet by its much smaller seeds that are only gray-brown in colour. Seedlings of Witch grass can be distinguished from those of Proso millet only by the size, shape and colour of the mother seed clinging to the primary root.
Herbicide Resistance
Triazine resistant (WSSA group 5) populations exist in Grenville, Grey, Haldimond/Norfolk, Prescott and Wellington counties (ON).For more information on weed resistance go to www.ontarioweeds.com\resistance
Management
Witch grass is well suited to take advantage of any excess nutrients in the soil, so over-fertilization should be avoided. Mowing will help to reduce seed production.
There are several herbicides registered for its control. One option is fluazifop-p-butyl (Venture L) applied at the 2-5 grass leaf stage. The 1 L/ha application rate should be adequate for control. Venture L does not provide any residual control and will only control those grasses that have emerged and are at the proper growth stage when applied. S-metolachlor (Dual II Magnum), sethoxydim (Poast Ultra) and terbacil (Sinbar) will provide witch grass control, as well as, spot applications of glyphosate and gramoxone (Paraquat).
References
http://www.ontarioweeds.com/weed.php?w=PANCA
http://www.gnb.ca/0171/10/Witchgrass%20in%20Blueberry.pdf
