Q.Could an overgrown holly bush cause two pear trees to die?
The holly bush has grown to approx. 2 feet above fence height. Could it block the light of two well established pear trees to the point of killing them?

Certified GKH Gardening Expert
It is unlikely that a bush form holly will grow tall enough to block light of a fruit tree, as they will quickly outgrow a Holly. There is more of a likelihood of the roots causing an issue though. If they are too close, then they could be preventing the pear tree from growing properly, which could result in their death.