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Pest Patrol: Dealing with cleavers

#PestPatrol with Mike Cowbrough, OMAFRA

Q: I had a field of winter wheat with cleavers in it and it was a pain. What is the best way to get rid of this weed in winter wheat?

An older seedling plant (left) with square stem and whorled leaves, and a close-up of the leaf whorls (right). photo: Supplied

A: I can’t think of a redeeming quality for cleavers, although apparently the fruit is considered one of the best substitutes for coffee (Malik and Vanden Born, 1988). No thanks. Cleavers are covered in curved, hair-like bristles that irritate skin (see photo at bottom) and cling to almost anything. High cleaver densities in cereals will cause severe lodging, reducing harvesting efficiency and causing yield losses of 30 to 60 per cent.

There are a handful of effective herbicides that control cleavers in winter wheat (table 1 below). Unfortunately, if your crop was under-seeded with red clover, they would all significantly injure any emerged plants.

*OMAFRA Publication 75A, Guide to Weed Control

Other considerations: Since cleavers will emerge throughout the spring, summer and fall, any new seedlings that germinate after cereal harvest should be managed. And since cleavers are also fairly shade tolerant, cover crops generally have not been effective at providing meaningful suppression of this species. Tillage or fall herbicide applications with glyphosate will control emerged seedlings.

A mound of cleavers pulled from a 10 m2 area. photo: Supplied
Skin irritation after pulling cleavers out of a wheat field during the 2017 season. photo: Supplied

Have a question you want answered? Hashtag #PestPatrol on Twitter to @cowbrough or email Mike at [email protected].

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