We all know tree's are tremendous "pumps" when it comes to pulling water from the soil and away from the desired turfgrass we're trying to as seen from the photo example below. Tree roots have been shown to graft with companion trees to branch out far and wide to satisfy their thirst for a drink. I'd be thirsty too if I had to haul several gallons of water up eighty feet. That's equivalent to the height of an eight story building! My back hurts just writing that.