Help! Leaves on Leyland cypress trees are rapidly turning brown.
What can I do to save the 8 mature leyland cypress trees that have leaves that are turning brown? Two much smaller trees are also starting to turn brown. The leaves, more on the bottom branches, but also some on the highest branches, are turning brown. Some of the smaller branches have fallen off of the leyland cypress trees. I see browning on young raspberry bush leaves as well. I cannot see any bugs on the plants but I know from past insect infestations that the bugs are not always visible to me. Should I cut off any reachable branches that are mostly or entirely brown? Is there any chemical that I should spray on the branches that are still mostly green or on the branches that are almost entirely brown? Thank you for any advice you can give.
The symptoms you describe sound like winter injury. Take a look at this recent article by our plant pathologist concerning winter damage in Leyland cypresses: https://marylandgrows.umd.edu/2018/04/11/why-is-leyland-cypress-turning-brown-winter-took-its-toll/
As noted in the article, there is no cure for winter damage. You can prune out the brown portions, just above where green color is still visible. If more than one-third of a tree is damaged, it may need to be replaced.