In my back yard I have multiple yews in a berm that runs for about 80 feet. They were planted in 2002 and have done well until this year. I live in Illinois, and last summer we had drought conditions. This spring I noticed yellowing or browning spots on the yews. They are not anywhere salt could get them so that is not the problem. The problem seems to be spreading and I'm worried I will lose these plants. I was told to try a fungucide. Is this the only treatment to help me save these plants?