Cypress canker, or Seiridium canker, is a common fungal disease that affects Leyland cypresses. It often presents as reddish-brown needles and can quickly spread throughout the tree. Pruning away infected branches and improving air circulation can help manage the disease.
The black wig borer is a beetle that can infest Leyland cypress trees: Adult black twig borers are light brown to black and about 1/16 in (1.6 mm) long. Adult females create entrance and exit holes on the underside of twigs. They introduce a fungus that feeds the beetles and can clog the tree's water-conducting tissue. All life stages of the black twig borer can be found in tunnels, or galleries, within the tree. Other pests that can affect Leyland cypress trees include:

• Cypress weevil: Adults feed on the bark of twigs, while larvae bore into the wood.
• Bagworms: Caterpillars feed on the tree, causing needle loss and slow growth.
• Scale insects: These small insects feed on the tree's sap, leaving behind a sticky residue.
• Spider mites: These cool-weather pests feed on the leaves, causing them to turn yellow or brown and die.

To prevent pests and disease, you can: Space new plantings to allow for good airflow, Water during droughts using drip irrigation, Remove diseased twigs and branches, and Disinfect pruning tools.

Yes. Same as the black wig borer insect.