Issue 1, April 22, 2013

Star-of-Bethlehem Control Options: When You've Had Enough of the Spring Flowers

I'm a big fan of spring bulbs and their resulting flowers, but I recognize that not everyone is. Sometimes, a seemingly decent plant can find itself in a location where it is not wanted. It can be labeled as a "weed". Gasp! This is a sad story for everyone (and every plant) involved.

I was recently asked how to control Star-of-Bethlehem (summer snow-flake), Ornithogalum umbellatum, in a landscape bed. This can be a difficult "weed" to control. In fact, many don't consider it to be a weed at all. This native of Europe has escaped cultivation and can be found statewide in Illinois. The flowers are typically bright, waxy and white yet occasionally bluish. They are present April through June on branched, open clusters that reach to about 30 cm high. They consist of 6 petals with a characteristic green stripe on the underside. The flower-stalks are leafless. The leaves are succulent and pale to dark green with a whitish grooved midrib on this cool-season perennial herb. Seed pods are produced in mid to late spring. Following this, plants die back to the ground. Reproduction is primarily by bulblets that develop surrounding the parent bulb.

To its detriment, Star-of-Bethlehem grows as tufts or clumps in lawns and landscapes which can be undesirable by some. Its early growing season has aided in its ability to escape cultivation. It's there and then it's gone. All parts of the plant are poisonous if ingested. Unfortunately, it is commonly confused with Allium species such as wild garlic and wild onion, both of which produce an oniony smell when crushed which is not present with Star-of-Bethlehem. Control tactics are similar for these species. For lawns, herbicide applications should be made in early spring when temps are at least 50 degrees. In the fall, make another application. In fact, complete control will likely require spring and fall applications for at least 2 consecutive years. If the population is small and you'd rather not use herbicides, you could try to cut plants back early to deplete the energy reserves. Digging up the bulbs may prove to be effective.

A few turfgrass herbicide options you could try include 2,4-D either alone or in a 3-way product. Ester formulations will likely be more effective. Follow label directions carefully to prevent vapor drift onto off-target sensitive plants nearby. Their new spring growth will be quite susceptible to herbicide injury. Additional recommended herbicides are sulfentrazone and carfentrazone. Again, sequential applications may be necessary for complete control. Mowing should be delayed following application to give the herbicide time to work. The label should specify the number of days. Read and follow all label directions.

These herbicides are not labeled for use in landscape beds. Spot treatments of the non-selective herbicide, glyphosate, could be tried but only marginal control may result. Physical removal of the bulbs may be the best option in these locations.

Even more recently, I was asked about controlling scilla, another spring blooming bulb that was growing in a lawn. Again, I was saddened; but I must remember that one man's flower is another man's weed. This ornamental will not likely be found on any herbicide label under the heading of pests controlled. However, the above recommendations for controlling Star-of-Bethlehem may hold true for this species.

If all else fails, embrace the flowers! They are short lived really. Perhaps you can offer the bulbs or plants free to a friend. Make a pot of coffee and chat with them while they dig! (Michelle Wiesbrook; Photo credit: Luke Cella)

Michelle Wiesbrook

Return to table of contents