Because of this similarity, seed stock can be contaminated easily. According to the Canada Seeds Act, cleavers is a class 2, primary noxious weed seed. Cleavers seed is a similar shape and size to canola, making it hard to mechanically separate cleavers seed from canola seed. Because of this similarity, seed stock can be contaminated easily. According to the Canada Seeds Act, cleavers is a class 2, primary noxious weed seed.
Cleavers competes with crops for light, moisture and nutrients.
Heavy infestations will cause yield reductions. In canola, one experiment showed a 20 percent yield loss when cleavers were present at densities of 100 plants per square metre. Cleavers is a major problem in many cereal and oilseed fields in western Canada. Its clinging, sticky vines often cause lodging of the crops, tangle up harvesting equipment and cause other difficulties which delay harvest. Cleavers flowers are almost unnoticeable, 1-2 mm in diameter, greenish yellow to white in colour and self pollinating The problem, and the weed, are spreading A single cleavers plant can produce 3,500 seeds .