A hot, complete, second-year May burn kills the emerging shoots before they can go to seed. Heavily infested stands are best controlled with the above sequence twice, separated by 2 years without burning. Problems with this method may arise if the burn is patchy, leaving viable seeds or second-year shoots unscathed. These plants would live to set seed. Recommended Practices on Lands Other Than High-Quality Natural Areas Same as given above for high quality areas, with the following addition.
Herbicide can be useful in controlling large sweet clover populations in degraded areas.
Following a fall burn, hand spray individual seedlings with an amine formulation of 2,4-D according to label instructions in spring, before native prairie vegetation emerges. To reduce vapor drift, use an amine formulation of 2,4-D rather than an ester formulation. The herbicide 2,4-D amine is selective for broadleaf plants. When applying either herbicide described above, spot application should be done such that coverage is uniform with the entire leaf being wet. Precautions should be taken to avoid contacting non-target plants with the solution.