Keep those cabbage butterflies away from your plants, the white ones.
Accept a 5-10% loss........
I'd guess you are near some agricultural fields with lots of butterflies?
I never saw a budworm when I was growing in the NorCal mountains.
They are a problem in the Central Valley of California.
do what they said above plus put cedar chips around the trunk. also go to a 99 cent store or dollar store and buy mothballs and some panty hose fill up the hose with the moth balls and tie a couple to your plants depending on size.