Cutworm Infestation - Help Please

My friend has had a Cutworm infestation that has decimated her Fall sown Beets. Manually removing the grubs from the plants during the hours of darkness has proved unsuccessful so the crop has been removed from the raised garden bed leaving no crops to feed the larvae. She is hoping that without a food source any remaining grubs will not pupate in the soil and therefore die. She has been advised that Nematodes can kill the larvae, but it is now too cold for them to act.

She thinks that the Cutworm moth eggs can remain dormant in the soil until they hatch into new larvae next spring. Please can you advise if there is anything that can be done now to treat the soil to ensure the larvae do not hatch to attack her new plants in the spring.

Thanks so much everyone!