Thursday, December 1, 2022

Burndown Wild Garlic, Grape Hyacinth and Star-of-Bethlehem

  • By Larry Steckel •
Picture 1. Blue flowers distinguish grape hyacinth from wild garlic

This spring some fields seem to be infested more heavily with wild garlic, grape hyacinth and in a few cases, star-of-Bethlehem. These three weeds, in the Lily family, are often mistaken for each other as they all derive from bulbs and are low-growing perennials.

In particular, grape hyacinth and wild garlic look very similar as they both have round hollow leaves that end in a point.  The best way to tell them apart, before grape hyacinth flowers, is that wild garlic has a distinct odor when cut or crushed and grape hyacinth does not.  Once grape hyacinth flowers they are easy to tell apart as that plant has distinct blue flowers that somewhat resemble a grape (Picture 1).

Star-of-Bethlehem has flattened leaves with a prominent mid-rib.  That leaf architecture really tells it apart from the other two weeds. Its flowers are white.

From a burndown before planting perspective, if the infestation is low then the typical glyphosate + dicamba or glyphosate + Verdict burndown will do a good enough job.

Please note that these options provide only about 50% suppression. However, in fields with heavy pressure, these weeds can make uniform stand establishment more of a challenge and a more effective option is needed. The herbicides with the best activity on these Lily family weeds are Firstshot, 2,4-D and Elevore.

My understanding is that the herbicide that has good activity on wild garlic and is in relatively better supply is Firstshot.  The use rate is 0.6 to 0.8 oz/A. This herbicide is very effective on wild garlic and from observations through the years has shown some decent activity on grape hyacinth and star-of-Bethlehem.

The plant back to soybeans is 7 days and to cotton, corn and grain sorghum is 14 days.

The two auxin herbicides that are pretty effective on these weeds are 2,4-D and Elevore.  2,4-D is in extremely short supply but if you happen to have some in the shed a quart rate of either the ester or amine formulation will do a pretty effective job.

I do not have as much experience with Elevore on grape hyacinth or star-of-Bethlehem, but on wild garlic, our research would indicate very good activity. Elevore is also limited in supply but if you are able to access it the rate is 1 oz/A.

The plant back to corn is 3 days (label specifies planting depth at least 1.5”), while soybean and grain sorghum is 14 days and cotton is 30 days.

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Larry Steckel is an Extension weed specialist at the University of Tennessee and can be reached at lsteckel@utk.edu.

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