I recently bought a property that came with a dozen established fruittrees; one of them is a massive sweet cherry that produces the most delicious cherries (Which is hard to pull off in the climate I live in). The cherry tree is almost 20 ft tall so I don't think it's been grafted (original root stock). I'm not sure if its because it age, a fungal infection, or years of neglect but it's been dying off quite quickly during the summer despite being irrigated. I plant to heavily prune it back but I'm not sure its going to make it. I would love to keep this genetic line but I'm not sure the best way to go about it. Should I try and propagate them from seed? Or graft some branches on to some other already established trees?