Why Is My Leyland Cypress Turning Brown?

Read the pattern first

NC State's Plant Disease and Insect Clinic publishes a step-by-step key for cypress-type trees. It starts with where the symptoms are: needles only, or bark and branches too, and whether the change is even across the tree or patchy. This table condenses its main branches for Leyland cypress:

Roanoke Tree Removal is a local referral service: we pass your request to an independent, local tree crew. We are not a government office or a plant clinic, and this page is general information, not a diagnosis.

Normal fall browning

The guide's first non-disease answer is one many owners miss: the oldest needles turn brown and drop every year, and needles deep inside a dense screen die from shade. Fall is when you see it. If the outer growth is green and the brown is all inside, there is nothing to treat.

Seiridium canker

NC State Extension lists cypress canker, caused by Seiridium fungi, as a major Leyland disease: shoot tips and side branches die back, resin oozes from bark cracks, and the bark shows dark brown or purplish patches. The clinic's key adds that the dead tips are often slightly orange, can appear at any time of year, and end at a sharp line between dead and living wood. Mississippi State Extension says spores spread in splashing water and on pruning tools, and that resin alone does not prove canker, since healthy Leylands leak resin too.

There is no spray that cures it. West Virginia University Extension says fungicides are not effective, and Mississippi State says chemical control is not available. Its advice: cut diseased branches several inches below the canker edge, prune only when the tree is dry, and wipe tools with 70% isopropyl alcohol between cuts. A canker on the main trunk kills everything above it.

Needle blight from the bottom up

NC State calls Passalora needle blight the most important Leyland disease in Christmas tree plantings. Mississippi State says it starts in the lower, inner canopy and moves out toward the branch tips, with needles turning brown and then gray. Infection is favored around 68 degrees with high humidity, and symptoms show about three weeks later. Fungicides can prevent new infections but do not cure existing ones. Spacing does more: Mississippi State suggests removing every other tree in a crowded planting to let air move.

Bot canker, roots and wet ground

Botryosphaeria canker starts as yellowing and browning, then sunken, often V-shaped cankers girdle branches, usually with little or no resin, per NC State. It hits trees under heat and drought stress, and in some areas it is more common than Seiridium.

Roots are the other half. Mississippi State says Leylands need well-drained soil and do poorly on heavy clay or wet sites, where twig dieback and Phytophthora root rot follow; roots that are dark inside are a sign. The NC State key offers a quick field check: if the outer layer of a root slides off the inner core when pulled, the root is rotting.

Bagworms

Virginia Cooperative Extension's 2025 bagworm guide says eggs hatch in early June and the caterpillars feed until August, and stripped branches are usually most noticeable near the top of the tree. Treat in mid-June while the larvae are small; insecticides do not get through the bags later. From fall to spring you can pick the bags off and destroy them, and cut away the silk band, which can girdle a twig years later. VCE notes that heavily infested plants with sparse, brown foliage may be better removed than treated.

Why Leylands struggle here

VCE's Leyland cypress fact sheet calls disease the species' weak point, seen mostly on stressed plants. Its advice is to avoid poor soils and water during drought. It also records that Leylands were damaged and killed in Blacksburg after the record low of minus 18 degrees on February 21, 1985. Many nursery Leylands have several trunks from shearing, which VCE says can split apart under heavy snow or ice. NC State says the species can top 100 feet and grows 2 to 3 feet a year on typical southern sites, which is why screens planted close together crowd and shade each other.

Getting a firm diagnosis

For a lab answer, Virginia Tech's Plant Disease Clinic charges $35 for an in-state sample, and your local VCE office can help you send photos, a physical sample or both. NC State's guide says to include the zone where living and dead wood meet for cankers, and roots with soil for root problems. If the question is whether a tree is safe near the house, an arborist risk assessment answers that.

When removal makes sense, and what it costs

Removal is usually the practical answer for a tree with canker in the main trunk, a tree that has browned from the bottom most of the way up, or a heavily defoliated tree. NC State adds a stump tip: because Leylands are susceptible to Heterobasidion root rot, grind fresh stumps below the soil surface.

HomeGuide's figures are national, not Roanoke quotes. See tree removal cost by size, stump grinding cost and tree removal cost in Roanoke.

Replanting a screen

VCE suggests similar conifers such as Thuja 'Green Giant' or Thuja Steeplechase. Mississippi State lists Arizona cypress, arborvitae and Japanese cedar as less susceptible to canker, and says to space trees widely so they do not crowd. Leave room for the mature width, not the width at planting. To have a browning Leyland or a whole screen looked at, call (540) 904-1819 or use the form, and we will pass it to an independent local crew. Tell us how many trees, roughly how tall, and how close they are to the house, fence or lines.

Sources

• NC State Plant Disease and Insect Clinic, Identification and Decision Guide for Cypress Problems (updated Feb. 27, 2026) (Checked Oct 12, 2026)
• NC State Extension, Leyland Cypress, Christmas Tree Notes (reviewed Feb. 2024) (Checked Oct 12, 2026)
• Mississippi State University Extension, Diseases and Disorders of Leyland Cypress, P3621 (PDF) (Checked Oct 12, 2026)
• West Virginia University Extension, Seiridium Canker (Checked Oct 12, 2026)
• Virginia Cooperative Extension, Leyland Cypress, HORT-18NP (Niemiera, reviewed March 2024) (Checked Oct 12, 2026)
• Virginia Cooperative Extension, Bagworms in Virginia, ENTO-624NP (revised July 15, 2025, PDF) (Checked Oct 12, 2026)
• Virginia Tech Plant Disease Clinic, Submitting Samples (Checked Oct 12, 2026)
• HomeGuide, tree removal cost (national figures, updated Feb. 2026) (Checked Oct 12, 2026)

Common questions