When Rory tells Luke that she went golfing with her grandfather, he tells her that golf courses are an environmental blight because of the chemicals golf courses use to keep the grass green.
Golf courses use pesticides and fungicides to care for their turf – the same stuff home owners put on their lawns. By area, golf courses actually use less chemicals than regular lawns, but the vast expanses of grass on golf courses mean that by volume they use a lot more. Aware of the environmental impact, many golf courses are using less chemicals than before, and some have gone completely organic.
The main environmental problem with golf courses is the enormous amounts of water they use to keep the grass green, leading to further scarcity of this limited resource.