FAQ

My 9-year-old Leyland cypress is turning rust-colored and dying, and I've been told cypresses often die at around 8 years old. I've also been advised to spray it with horticultural oil. Should I remove the tree, or is there a way to save it?

Branch dieback on leland cypress is commonly caused by canker disease and this is the likely causal agent for the problem on your trees. Trees that are stressed by drought or excess soil moisture are more susceptible to this disease. We also find that trees that have been planted too deep and have soil over the top of the root flare are more prone to disease.

Pruning out diseased branches and identifying and correcting any stress inducing factors will help prevent further decline. Many homeowners choose to replace leland cypress with more durable species. I recommend that you consult a local arboretum/botanical garden for suitable replacement species.

Horticultural oil will not help the situation unless there is an insect infestation present that is causing plant stress. Leyland cypress can be infested with spidermites and scale insects that can be suppressed with properly timed treatments of horticultural oil.