1.   As a result, pitch canker has had a profound impact on landscape designers and nursery growers.

2.   A virulent and incurable fungus known as the pitch canker is sweeping through the last stands here, killing healthy trees and threatening to turn the verdant hills brown.

3.   But pitch canker threatens more than Christmas trees.

4.   Despite the infection, the native stands are considered the best hope for combating pitch canker.