Sage requires no burning of gasoline for mowing. It only needs to be renewed, through cuttings taken from old plants, and stuck in soil that remains moist, to become new, young plants.
Nearby lavender plants, and a chrysanthemum, also appear to be dead. My guess is that they suffered from some of the cold weather we had without insulating snow this winter, but I can’t really be sure. It could be disease, but the multi-species death leads me to think not.
Deer tend to get the blame for eating plants like this, but I’m more inclined to blame the rabbits, woodchucks, or the squirrels – something with an eye close to the ground, and a brain that can’t remember that it’s the autumn crocus that has flavorful saffron for a pollen.