Can you spray broad leaf weeds in middle or even late summer and still kill them okay with 2-4-D?

Any time the plants are actively growing they can be killed with 2-4-D, when the plants are actively growing they are more likely to absorb the pesticide into their bodies. When it is very hot or after they have set seed the plants are often no longer growing and not as likely to absorb water and the chemical and move them around from one part of the plant to another.