General types are spread all over the lawn and need to be reapplied on a regular basis. Systemic weed killer work more slowly but kill the weed and its root. Regular mowing will also prevent them from spreading. Thistle is a broad leaved weed with purple flowers and coarse foliage, they can be treated with weed killer. Regular mowing will also prevent them from spreading.
Daisies are a broad leaved weed with small, white flowers with yellow centers.
These need to be spot treated with a weed killer. Regular mowing will prevent them from spreading. Crabgrass is a grassy weed, it has long stems with nodes from central rosette. General weed killer can be applied. Wild onion is a grassy weed, it has long , straight stems and grows in clusters with a strong odor.