Photo: Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org, wild garlic,Allium vineale
The plants are similar in appearance and habitat - upright, unbranched foliage that appears grass-like; and the ability to grow in a wide variety of soil conditions. There are differences though. The leaves of garlic are smooth, round and hollow; while onion leaves are flat and not hollow. Foliage of either emits a strong odor when crushed. Garlic produces flowers and dormant bulbs on the flowering stem; onion only produces flowers. These reproductive structures are produced in the spring. Both plants also reproduce from underground bulblets. Some of the underground bulblets germinate in the fall, while the hard ones germinate in the spring.
Wild garlic and onion can be a problem in turf, nursery production or in the landscape. Plants can be dug out, but care must be taken to remove the underground bulblets. Hand pulling is not affective because the foliage breaks and the bulblet is left behind. You can also ignore the problem since the foliage is a visual issue early in the growing season; and with natural senescence and mowing, goes away.
Photo: Ohio State Weed Lab Archive, The Ohio State University, Bugwood.org wild onion Allium canadense
There are no pre-emergent herbicides to use against these plants. Post emergent herbicides include but are not limited to: 2,4-D + MCPP + dicamba; metsulfuron (turfgrass use only); sulfentrazone + metsulfuron (turfgrass use only); sulfosulfuron (turfgrass use only); or glyphosate.
Remember to always read the label for specific application sites, precautions and mix rates.