A few years ago I planted some Leland Cypress: during this winter they have begun to experience a problem of brown branches where they branch leaves turn brown and droop. Can find no evidence of pests. Cause - cure?
Please send us photos so we can see what you are dealing with. There are several insects and diseases that can impact Leyland cypress, not to mention problems caused by improper planting, root damage, drought, and other abiotic problems.
Send photos of the whole tree, around the base of the tree, and affected foliage.