Ontario Weeds: Large crabgrass
Excerpt from Publication 505, Ontario Weeds,
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Large crab grass is an annual weed reproducing only by seed.
Large crab grass is common in southern Ontario but also found in northern and northwestern Ontario in row crops and other fields, waste areas, gardens, and lawns.
Large crab grass is often confused with smooth crab grass, proso millet and witch grass. Large crab grass seedlings often resemble witch grass seedlings but large crabgrass seedlings are covered with shorter hairs than witch grass seedlings. Large crabgrass differs from other weeds as it has no auricles, hairy leaf sheaths and their finger-like spikes are distinctive.
Large crab grass resistant to all WSSA Group 1 herbicides (fops and dims) has been documented in Ontario.
Figure 1: Membranous ligule of large crab grass
Figure 2: Large crab grass leaf blade which is hairy on both sides
Figure 3: Leaf sheath of large crab grass which is hairy but the leaf margins are hair-less
Figure 4: Large crab grass seed head
Figure 5: Mature plant of large crab grass
... on general Weed
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