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Identification of Seedling Kochia and Horseweed (Marestail) (04/30/20)

The landscape is greening up and planting activities have begun across North Dakota. I have received a few questions for some tips and tricks to help differentiate seedling kochia from seedling horseweed (marestail).

The landscape is greening up and planting activities have begun across North Dakota.

I have received a few questions for some tips and tricks to help differentiate seedling kochia from seedling horseweed (marestail). While most of us are familiar with kochia, horseweed is a relatively new weed for us and at times can be confused with small kochia seedlings. Here are a few brief descriptions and pictures of each weed to help identify them at early growth stages this spring.

Kochia often germinates in very dense mats consisting of numerous individual plants. These mats often appear to be dull green due to kochia’s leaf color. Young kochia seedlings are very densely hairy and will often be described as “puffballs” due to the dense hairs. Kochia cotyledons are linear. Leaves are linear to lanceolate and taper to a point.

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Most of our horseweed will germinate in the fall, then overwinter as a rosette, and begin to bolt in the spring. With abundant rainfall across the state last fall, there should be plenty of overwintered horseweed plants ready to bolt or already bolting as we enter May. There is a smaller percentage of plants that do not germinate until the spring, and these plants bolt almost immediately after emergence and can be more readily confused with kochia seedlings. Unlike kochia, horseweed seedlings will rarely be found growing in dense mats. Horseweed cotyledons are oval shaped and easily distinguished from kochia cotyledons. Young leaves are oval shaped and become more linear as the plant matures. Most horseweed leaf margins are toothed or lobed.

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Joe Ikley

Extension Weed Specialist

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