My 3 hemlocks all have developed sig ificant yellow-orange needles within past 3 weeks. Is affecting 10 to 30 percent of the needles. Was not a particularly dry summer, although humid here in southeast PA. They were all healthy before this started.
Chester County Pennsylvania
Hello and thanks for using the Ask an Expert System.It is difficult to diagnose your problem based on the limited information you have provided. Hemlocks are under attack from two imported insect pests and a number of fungal diseases. The insect pests are hemlock woolly adelgid and elongated hemlock scale. The major diseases are outlined in a fact sheet from Penn State Extension called Hemlock Diseases
I recommend that you contact the Chester County Master Gardener Hotline. You can provide additional information and perhaps a solution.