Elaegnus leaves turning black
There is a stand of Elaegnus about 2Mx3M in the garden of our new to us property but there's an area about 1Mx1M where all the leaves have turned black. I can't see any insects or fungus on the leave, they just turn black and die. There's a similar stand on the other side of the garden which doesn't have this problem, I'll be very grateful for any suggestions to stop the whole stand, and potentially the other one, dying away.
I've added pictures in case I misidentified the plant.