Some pics of Fiesta applied about 5-7 days ago. Dandelions especially turn black very quickly and dry up and disappear.
Here is a before and after comparison - second photo about 16 hours later.
Dandelions in a lawn starting to shrivel and turn black. This lawn is not very healthy. A good fertilizer program within a comprehensive lawn care package will thicken the lawn and help keep weeds from taking over.
Fiesta will work even in cool weather. Here are some weeds sprayed in early November.