Applying a herbicide in the fall can be tricky due to weather and harvest conflicts (compared to weather and planting conflicts for a spring preemergent program).
In this study, Fierce, Spartan, and Valor provided equal or better control when they were applied in the fall, compared to spring. However, other products did a great job of managing very small Kochia, and many products had good control on larger Kochia (still <1").
With the correct product and pre-emergent application timing, followed by good timing and product selection with a postemerged application, even large populations of glyphosate-resistant +Kochia can be managed.