Leyland cypress turning brown

Leyland Cypress Diseases, Insects & Related Pests

Leyland cypress (x Cupressocyparis leylandii) has grown in popularity in the Southeast over the last few decades, especially in its use as a fast-growing, screening plant. With the increased planting that has resulted from its popularity, various diseases and pest problems have become more evident.

As with any plant, the first step to a healthy Leyland cypress is to provide it with the cultural conditions that it needs. Ultimately, a vigorously growing plant is always better able to survive disease and insect problems than is a stressed one. In general, Leyland cypress requires full sun, and prefers moderately fertile soil that is moist and well drained. For further details on providing a Leyland cypress with the conditions under which it grows best, see HGIC 1013, Leyland Cypress.


Seiridium Canker/Dieback: In the Southeast, this disease is caused most often by the fungus Seiridium unicorne. Generally speaking, cankers are dark, oval or elongated lesions that are usually dry, may be sunken with a raised edge, and are surrounded by living tissue. More specifically, Seiridium cankers form on stems, branches and in branch axils. They are often thinly elongated, shallow, and the surrounding bark shows a dark brown to purplish discoloration. A single Seiridium canker does not enlarge to girdle a branch. Instead, multiple cankers form around a branch, reducing water flow significantly. In addition, the cankers are often accompanied by an extensive flow of resin from cracks in the bark. However, resin flow by itself is not a defining characteristic of this disease as it often occurs in otherwise healthy Leyland cypresses. A shallow cut at the site of the canker typically reveals tissue beneath the bark that is reddish to brown in color and sticky. Branches affected by Seiridium canker experience dieback. They are often yellow to grayish tan to reddish brown in color and usually appear randomly distributed on the tree. When a cankered branch has only recently shown a change in color, needles will fall off easily when a hand is run along the branch. Generally, the discolored branches are the symptom noticed first. If the fungus gets into the main trunk, it can kill the entire tree.

Oozing sap is a symptom of Seiridium canker and dieback.
J. Williams-Woodward, Univ. of Georgia

Branch dieback is a symptom of Seiridium canker and dieback.
J. Williams-Woodward, Univ. of Georgia

Environmental conditions that stress Leyland cypress (especially drought, but also spring freeze damage) favor the development of infection. The fungus survives winter in infected tissue. Spore-producing structures of the fungus appear on the surface of the canker as small, black dots that are barely visible without a magnifying lens. Spores can be spread (within the tree and to new trees) via rain, overhead irrigation and pruning tools, typically entering the trees through wounds and cracks in the bark. From the point of infection until development of cankers and other symptoms often takes years.

Prevention & Treatment: When planting as a screen, provide enough space (a minimum of 12 to 15 feet) between trees for good air circulation and to minimize stress as they mature and enlarge. Avoid over-fertilization. Place mulch under trees to at least the drip line (and preferably further) to reduce water evaporation and competition for water as well as potential damage to trees from lawn mowers and string trimmers.

Drought-stricken trees are significantly more susceptible to infection. However, field trials have shown that trees inoculated with Seiridium unicorne that developed cankers were able to heal within 1-2 years once a regular irrigation schedule was implemented. As such, make sure Leyland cypresses are irrigated during drought or semi-drought conditions. Apply water at the base of trees to keep branches dry and reduce disease spread. If overhead irrigation is necessary, it should be applied very early in the morning.

Prune out and destroy diseased branches as soon as possible. Make pruning cuts 3 to 4 inches below diseased tissue. Sterilize pruning tools between each cut by dipping in a 10 percent bleach solution (1 part chlorine bleach to 9 parts water)*. Severely affected trees should be removed and destroyed. *Note: Be sure to clean and oil pruning tools after this procedure to prevent rust formation.

Fungicides are not considered an effective or practical means for controlling canker diseases in general or Seiridium canker in particular.

Phytophthora Root Rot: Leyland cypress is susceptible to the root-rotting fungus Phytophthora. Root rot is primarily a problem in soils with very poor drainage. Young plants are most often affected. Mature, established trees are seldom affected. Phytophthora species that cause root rot live in the soil and enter a healthy tree through wounds or the succulent parts of small roots. As the fungus destroys the roots, symptoms of distress become apparent above ground. Foliage becomes stunted, sparse, changes color (yellow, purple, tan) and dies. Cankers may be visible at or below the soil line.

Prevention & Treatment: Remove and destroy infected plants including the entire root system. There is no practical chemical control for home gardeners. Improve soil drainage by adding organic material to heavy, clay soils and avoid overwatering. If replanting, do not plant a Leyland cypress or other susceptible species where Phytophthora is known to be present.

Discoloration caused by Botryosphaeria dieback.
Robert L. Anderson, USDA Forest Service, www.insectimages.org

Botryosphaeria Dieback/Canker: This disease is caused by the fungus Botryosphaeria dothidea. As with Seiridium canker, symptoms include dieback with branches turning yellow to brown in color – typically the first symptom noticed. However, unlike Seiridium canker, needles generally do not fall off when running a hand down a recently affected branch. Examination of dead stems often reveals more deeply sunken (often V-shaped) cankers than found with Seiridium canker. In addition, these cankers often girdle a stem, killing the stem beyond the canker quickly. There may be cracks on the surface of a canker, and surrounding bark may be darker than that seen on a healthy branch. Botryosphaeria canker may exhibit little or no oozing resin. Cutting into an affected branch reveals dark brown discoloration with a definite margin between diseased and healthy tissue.

The fungal pathogen (disease-causing agent) overwinters in bark and diseased tissue. Spore-producing structures of the fungus appear on the surface of the canker as small, raised, black dots that are best seen with a magnifying lens. Spores are spread by water from rain and overhead irrigation as well as pruning tools.

Prevention & Treatment: As with Seiridium canker/dieback, environmental and cultural stresses predispose Leyland cypress to Botryosphaeria canker/dieback. Follow Prevention & Treatment recommendations provided above for Seiridium canker.

Blighted lower canopy commonly seen with Passalora needle blight.
Steven Jeffers, ©2010, Extension Service, Clemson University

Passalora Needle Blight: Although often referred to as Cercospora or Cercosporidium needle blight, this disease is caused by the fungus Passalora sequoiae (previously known as Cercosporidium sequoiae, Asperisporium sequoiae and Cercospora sequoiae).

Typically, this disease only affects plant growth that is at least one year old. Symptoms usually appear during summer months. They include browning of needles and eventual needle drop. These symptoms start on lower branches near the trunk and then spread outward toward branch tips. Over time, the disease moves up the tree. The portion of a tree displaying symptoms may increase from one year to the next until only the tips of upper branches are still green or the tree dies completely. The disease will sometimes be more prevalent on one side of the tree then the other, especially when irrigation spray is a contributing factor. When irrigation spray is not an issue, it is more likely to be seen on the north and west sides of trees where the morning sun is not able to dry branches as quickly.

In cases of severe disease, all needles (except current year’s growth) turn brown, resulting in green needles being present only on branch tips. Spores develop during late spring to summer. They are spread primarily by rain, overhead irrigation, and wind, but also by tools.

Brown needles seen in Passalora needle blight.
Alan Windham, ©2010, University of Tennessee

Spore forming structures of Passalora sequoiae are visible on infected needles.
Alan Windham, ©2010, University of Tennessee

Passalora needle blight symptoms somewhat resemble symptoms seen in a Leyland cypress that is responding to severe environmental stress, such as drought, in which its lower, interior needles turn yellow and drop.

Prevention & Treatment: When planting, space trees to allow adequate air flow. To minimize spread of spores, avoid overhead irrigation or restrict it to early morning hours. Preferably, use drip irrigation and make sure that enough water is being applied during drought situations. Drip irrigation hoses should be no more than 75 feet long as pressure drops significantly after that point. Prune out diseased limbs, disinfecting pruning tools between cuts using 10 percent bleach solution (1 part chlorine bleach to 9 parts water). Note: Be sure to clean and oil pruning tools after this procedure to prevent rust formation.

Fungicides such as thiophanate-methyl and myclobutanil (see Table 1 for examples of products) are recommended for use against needle blight. However, to be effective, these sprays need to begin in late spring and continue through summer until the cooler, less humid months of fall. In addition, when applying these materials, it is essential that needles, including those on the inside near the trunk, are thoroughly sprayed to run-off. Once a tree is tall, adequate coverage by a homeowner is generally not feasible.

Insects & Related Pests

Bagworms: Bagworms (Thyridopteryx ephemeraeformis) infest many shrubs and trees, but conifers (evergreens) are the preferred hosts. Damage to plants results from feeding by the caterpillars, which causes loss of needles. Mild infestations of this pest slow the growth of Leyland cypress. Heavy infestations can kill a plant.

Bagworms (Thyridopteryx ephemeraeformis) are often mistakenly identified as cones.
James B. Hanson, USDA Forest Service, www.insectimages.org

The adult male bagworm is a dark-colored, hairy moth with a 1-inch wingspan and clear wings. The adult female does not have wings or legs, is yellow, and appears almost maggot-like. The larvae (immature forms, aka caterpillars) range in size from about 1/8 inch to 2 inches depending on maturity. Each larva produces a carrot- or cone-shaped bag that it carries as it feeds. The bag is formed from silk that the larva produces. As it feeds, the larva adds bits of plant material to the bag for camouflage. The bag is about 2 inches long when complete. Home gardeners sometimes mistakenly identify it as a pine cone.

In South Carolina, bagworms survive the winter as eggs in a bag. The larvae hatch during May. Each one produces a strand of silk that allows it to be blown by the wind to a new location on the same plant or to a new plant. They soon begin to spin their cases. When mature, each larva pupates (transforms to an adult) within its bag. An adult male moth emerges from its bag in late summer (August/September). It locates an adult female in her bag. After mating, the female lays 500-1,000 eggs in her bag and dies.

Prevention & Control: Several parasites and predators feed on bagworms, generally keeping their numbers under control so that damage is not noticed. Removal of the egg-containing bags during winter and early spring is a very effective method for preventing problems before the next growing season. Once removed, the bags should be destroyed or placed in a deep container (5-gallon bucket), which allows beneficial parasites that may also be present in the bags to escape while retaining the bagworm larvae.

If an infestation is severe or the bags are out of reach, spray with the bacterial insecticide, B.t. This insecticide contains spores of the bacterium, Bacillus thuringiensis, which when eaten, kill the caterpillar. Young larvae are much more susceptible to B.t. than are older larvae. As such, apply this pesticide in the spring as soon as bagworms are seen (usually in May) and repeat two weeks later. Control is most effective when spraying is done in late afternoon or early evening. This insecticide is very safe to use. Once the bags have reached ¾ inch long, the efficacy of B.t. sprays decreases rapidly.

Sprays applied later in the season (May and June), when bagworms are larger must be with a contact insecticide, such as permethrin, cyfluthrin, lambda cyhalothrin, malathion or acephate. Note that these insecticides will also reduce populations of beneficial insects (predators and parasitoids) that help control spruce spider mites, which can result in an outbreak of this occasional Leyland cypress pest. Soil application of neonicotinoid insecticides, such as imidacloprid or dinotefuran only give minimal (less than 10%) control from bagworm damage, and should not be substituted for spray control. See Table 2 for examples of products. As with any pesticide, read and follow all label directions and precautions before using. Again, once a tree is tall, adequate coverage by a homeowner is often not feasible.

Mite eggs (red) and leaf speckling caused by mite feeding.
Eric R. Day, Virginia Polytechnic Institute and State University, www.insectimages.org

Spruce Spider Mites: Mites are not insects but are more closely related to spiders. Spruce spider mites (Oligonychus ununguis) are occasional pests of Leyland cypress. They are very small and not seen easily with the naked eye. They have piercing mouthparts that they use to suck plant sap. Their feeding results in speckling (formation of tiny yellow spots) on needles. Some needles may turn brown and drop off. With heavy infestations, fine webbing may be seen on the plant. Several seasons of heavy mite feeding may kill a Leyland cypress. Although most spider mites increase in number during hot, dry weather, spruce spider mites are cool-weather mites. Their population peaks during spring and fall, but drops dramatically during the heat of summer when predators feed upon them.

Prevention & Control: Naturally occurring enemies of mites include various predator mites, lady beetles (ladybugs) and other insects. These predators will usually suppress mite populations. Since insecticide use kills beneficial predators as well as mites, insecticides should be avoided unless absolutely necessary. Overuse of insecticides can result in population explosions of mites by their natural predators. However, insecticidal soap and horticultural oil sprays are less harmful to beneficial insects. Mites can be removed with a strong spray of water, when applied on a regular basis as needed.

To determine whether miticide use is needed, it helps to know how many mites are present. Hold a white sheet of paper under a branch and tap the branch with a pen. The mites that are knocked off will be seen crawling around on the paper. If dozens of mites are seen per tap, serious damage can result. Continue to check population numbers at 7- to 10-day intervals. Populations will be greatest during the spring and fall.

Pesticides labeled for homeowner use against spruce spider mites include insecticidal soap, horticultural oil, neem oil, tau-fluvalinate, lambda-cyhalothrin, and malathion. See Table 2 for examples of products that contain these active ingredients. As with any pesticide, read and follow all label directions and precautions before using. Again, once a tree is tall, adequate coverage by a homeowner is often not feasible.

An adult female juniper scale (Carulaspis juniperi) resembles a tiny (1/16-1/20 inch in diameter) fried egg, as seen here on a juniper needle. Males have a more elongated shape.
United States National Collection of Scale Insects Photographs Archive, USDA Agricultural Research Service, Bugwood.org

Scales: Various scale insects, including juniper scale (Carulaspis juniperi), Maskell scale (Lepidosaphes pallida) and minute cypress scale (C. minima) feed on Leyland cypress trees.

Scales are unusual insects in appearance, and as a result are sometimes misidentified by gardeners either as parts of the plant itself or as disease organisms rather than insects. Adult female scales are small and immobile, with no visible legs. They secrete a waxy coat that varies significantly in shape and color depending upon the species. Adult males tend to be very small and have wings which allow them to fly so they can locate females. Immature scale insects are called crawlers, and as the name indicates, they have legs and are mobile.

Adult females survive the winter on the plant. In spring, they lay eggs under their shells. The crawlers hatch and crawl around before settling to feed. They feed by piercing a leaf, stem or branch with their mouthparts and sucking sap. Their feeding can weaken or kill branches.

Symptoms of a scale infestation of Leyland cypress are very similar to those of spruce spider mite infestation. Initially, the Leyland cypress appears off-color, and infested branches show little growth. The needles eventually turn yellow or brown. Branches may die back. If ignored, a scale infestation may kill the plant within two to three growing seasons.

Prevention & Control: Depending on the size of the tree and how extensive the infestation is, sometimes scale can be removed by scraping them off the plant. If the scale infestation is somewhat localized, removal of infested branches can reduce the population significantly. Various beneficial insects help keep scale insects under control. If insecticides become necessary, try to use those that are “beneficial insect friendly”. These include insecticidal soap and horticultural oils.

The presence of adults or crawlers determines which treatment will be most effective. The waxy coating on adult scales protects them from traditional insecticides, but their crawlers are susceptible. Use a horticultural oil spray in late winter or very early spring before new growth occurs to control adult females by suffocation. Insecticides recommended for use against crawlers include horticultural oil, insecticidal soap, permethrin, cyfluthrin, lambda-cyhalothrin, carbaryl, malathion and acephate. See Table 2 for examples of products. Read and follow all label directions and precautions before using.

Table 1. Fungicides to Control Leyland Cypress Diseases.

Fungicides Examples of Brand Names & Products
Myclobutanil Spectracide Immunox Multi-purpose Fungicide Concentrate
Ferti-lome F-Stop Lawn & Garden Fungicide
Monterey Fungi-Max
Thiophanate-methyl Cleary’s 3336-WP Turf & Ornamental Fungicide
Southern Ag Thiomyl Systemic Fungicide
Note: Chemical control of diseases on large trees is usually not feasible since adequate coverage of the foliage with a pesticide cannot be achieved.

Table 2. Insecticides to Control Leyland Cypress Insects & Related Pests.

Insecticides Examples of Brand Names & Products
Acephate Bonide Systemic Insect Control Concentrate
Bacillus thuringiensis (B.t.) Bonide Thuricide Bt Concentrate
Monterey Bt Concentrate
Natural Guard Caterpillar Killer Spray with Bt Concentrate
Safer Brand Caterpillar Killer Concentrate
Southern Ag Thuricide Bt Caterpillar Control Concentrate
Tiger Brand Worm Killer Concentrate
Cyfluthrin Bayer Advanced Vegetable & Garden Insect Spray Concentrate
Horticultural Oil Bonide All Seasons Spray Oil Concentrate
Ferti-lome Horticultural Oil Spray Concentrate
Monterey Horticultural Oil Concentrate
Southern Ag Parafine Horticultural Oil
Summit Year Round Spray Oil Concentrate
Insecticidal Soap Bonide Insecticidal Soap Concentrate
Espoma Earth-tone Insecticidal Soap Concentrate
Natural Guard Insecticidal Soap Concentrate
Safer Insect Killing Soap Concentrate
Garden Safe Insecticidal Soap Concentrate
Lambda-Cyhalothrin Martin’s Cyonara Lawn & Garden Concentrate; & RTS1
Spectracide Triazicide Insect Killer for Lawns & Landscapes
Concentrate; & RTS1
Malathion Gordon’s Malathion 50% Spray Concentrate
Hi-Yield 55% Malathion Insect Spray Concentrate
Martin’s Malathion 57% Concentrate
Ortho MAX Malathion Insect Spray Concentrate
Southern Ag Malathion 50% EC
Spectracide Malathion Insect Spray Concentrate
Tiger Brand 50% Malathion Concentrate
Neem Oil Bonide Neem Oil Concentrate
Ferti-lome Rose, Flower & Vegetable Spray Concentrate
Garden Safe Fungicide 3 Concentrate
Garden Safe Neem Oil Extract Concentrate
Natural Guard Neem Concentrate
Southern Ag Triple Action Neem Oil Concentrate
Permethrin Bonide Eight Insect Control Vegetable Fruit & Flower Concentrate
Bonide Eight Yard & Garden Ready to Spray (RTS1)
Bonide Total Pest Control – Outdoor Concentrate
Hi-Yield Indoor/Outdoor Broad Use Insecticide Concentrate
Martin’s Vegetables Plus Concentrate
Tiger Brand Super 10 Concentrate
Tau-Fluvalinate (miticide) Bayer Advanced 3-in-1 Insect, Disease & Mite Control Concentrate; & RTS1
Note: Chemical control of diseases and insects on large trees is usually not feasible since adequate coverage of the foliage with a pesticide cannot be achieved.

1RTS = Ready to spray (a hose-end spray bottle).

Caution: Pollinating insects, such as honey bees and bumblebees, can be adversely affected by the use of pesticides. Avoid the use of spray pesticides (both insecticides and fungicides), as well as soil-applied, systemic insecticides unless absolutely necessary. If spraying is required, always spray late in the evening to reduce the direct impact on pollinating insects. Always try less toxic alternative sprays first for the control of insect pests and diseases. For example, sprays with insecticidal soap, horticultural oil, neem oil extract, spinosad, Bacillus thuringiensis (B.t.), or botanical oils can help control many small insect pests and mites that affect garden and landscape plants. Neem oil extract or botanical oil sprays may also reduce plant damage by repelling many insect pests. Practice cultural techniques to prevent or reduce the incidence of plant diseases, including pre-plant soil improvement, proper plant spacing, crop rotation, applying mulch, applying lime and fertilizer based on soil test results, and avoiding over-head irrigation and frequent watering of established plants. Additionally, there are less toxic spray fungicides that contain sulfur or copper soap, and biological control sprays for plant diseases that contain Bacillus subtilis. However, it is very important to always read and follow the label directions on each product. For more information, contact the Clemson Extension Home & Garden Information Center.

Why are my leyland cypress turning brown?

Leyland cypress branches turn brown because of an infiltration of three types of fungi: seiridium, bought, and cercospora. These three fungi enter into the tree during the summer months when the heat enlarges the tree’s stomata (pores on the leaf) and allow entrance of the fungi.

Treatment for Leyland cypress trees turning brown.

The simplest course of action to remedy flagging Leyland cypress branches is to prune back the dead and dying branches using a pole pruner that has been disinfected with six parts water 1 part bleach. Secondly, spread 2 to 3 in of mulch all the way to the outer tips of the branches, and finally ensure that the tree stay watered during times of drought.

About Leyland Cypress in Georgia

Every year we get lots of calls from people seeing that their Leyland cypress trees are turning brown.

Leyland cypress trees are not the best trees to have in Georgia. Instead, we recommend Arborvitae green Giants. They grow at about the same rate, but they’re much hardier for our environment.

Leyland cypress is came from the United Kingdom, they are a hybrid tree, and the best way to describe their ability to live in Hotlanta is akin to trying to place an organ into a body of a different blood type. The bottom line is the body wants to reject the organ. That’s very similar to Leyland cypresses in our climate zone.

In Atlanta it is simply too hot, it gets too cold, and our rain is too sporadic In the Heat of the summer.

Leyland cypress trees like lots of water. They do not do well in times of drought. Effectively when it gets super hot, the pores on their leaf known as stomata open up and allow three type of fungi into their system. These three fungi are known as seiridium, bot, and cercospora.

Once in, the only effective treatment or remedy is to remove that section of the branch.

Poor Planting Practice

Another reason that Leyland cypresses are often stressed in Atlanta is because people plant them too close together. This causes the lelands to grow into each other, interfering with each other’s ability to gather light from the sun and photosynthesize. The result is that they have to shut down the branches that they just spent energy creating. This is not a good return on investment, in fact it’s a waste of energy that could have been allocated toward other growth such as roots, or trunk girth, or height Etc.

Root Stimulating Service

Also, often people will add root stimulators to Leyland cypresses. Stimulating root growth simultaneously reduces canopy growth giving less chance for fungi to attack new water sprouts. Also, developing a strong root system helps the tree to fight off future attacks.

If you would like to get on our schedule to have your Leyland cypresses Roots stimulated, please give us a call at 770-272-6747.

If you plan on doing the pruning of the dead and dying Brown Leyland cypress branches yourself, we would recommend using the Jameson pole pruners.

It is the tool that we use. For a hundred and thirty some odd dollars, it’s well worth it. The tool is super strong and super sharp. Honestly in comparison to having a tree service come out, it’s probably worth having the professional-grade tools. Especially if you want to do the best job for your tree. Yes, this is a paid link, so it’d be awesome if you use it. I may make a buck or two for doing this blog post 🙂

Even though we don’t do it a lot, if you would like to have us come out and prune your Leyland cypresses, we are happy to do it. I will say a head of time it’s a rather expensive service, but if you don’t feel like getting out and doing it yourself and you would like the pros to take care of it for you, we would be more than happy to serve you!!

As a consulting arborist I get this question a lot. And it’s no wonder when you think about the dramatic decline Leyland cypress have been undergoing. Throughout the region we can see the dark green foliage transition to a reddish brown then an ugly dead grey.

There are a handful of pests and diseases that commonly attack Leyland cypress but the primary culprit here is winter damage. The past two winters (one with a late freeze and the other with a deep freeze) were simply too extreme for many of these trees. As a hybrid of two Pacific Northwest species Leyland cypress are simply not designed for the winter extremes of our zone.

With some plants winter damage is obvious but it is trickier with waxy-leaved evergreens like the Leyland cypress. First of all the desiccation and dieback take a while to manifest, causing us to notice the impacts well after the fact and over an extended period of time, similar to what we see with the spread of disease. Second, the stress caused by winter damage makes the tree more susceptible to its common enemies, especially canker diseases, and it is possible that the final death blow is actually delivered by one of these secondary impacts. Visit this link to learn from West Virginia University’s extension office about canker and its role in Leyland cypress decline: https://shar.es/1q15JE

I see three basic management options:

  1. Do nothing. Let the damage run its course but run the risk of dead wood decay working its way into healthy tissue and causing further damage. You also run the risk of canker disease developing, which is even more likely spread to other parts of the tree or to other Leyland cypress trees.
  2. Prune out dead sections and/or remove dead trees. What is dead is dead and will not ‘fill in’ over time. Cutting out these sections minimizes further decay and reduces the likelihood of disease. Use sharp tools and be sure to sanitize them with alcohol or bleach solution when you move from one section of the tree to another or from one tree to another. If you suspect a disease like canker consider spraying the tree with a fungicide after pruning (and possibly during the following growing season). I recommend neem oil as an option that is biologically derived and has minimal impact on beneficial insects.
  3. Replace with hardier diverse species, keeping an eye toward natives. If you avoid monocultures you avoid the likelihood of a single pest or disease – or frigid winter – taking out your entire population at once. And consider wildlife habitat by planting native species such as eastern red cedar (a prime habitat tree), eastern arborvitae (a.k.a. eastern/northern white cedar) and eastern white pine. Native shrubs will also fill in a space very quickly and increase your butterfly and songbird visitors.

Finally, a word about watering. No matter their age, any stressed tree will benefit from a slow, deep irrigation (e.g. irrigation bags, soaker hoses, buckets with tiny holes) during hot dry periods. In fact, some suggest that newly planted or stressed Leyland cypress should be watered well into October or November to ensure that they have the vigor to withstand the stress of a harsh winter.

Shawn Walker is a consulting arborist and owner of Trees 101 (www.trees101.net) based in Shepherdstown, West Virginia.

Leyland Cypress Turning Brown!

I have a row of ten Leyland Cypress trees planted from 3 gal pots at 2 feet height on the property line 4 years ago, in full sun all day. They are now over 8 feet high and (until recently) have done very well. One of the trees has turned brown from the ground up….and is now 1/2 brown, easily apparent on either side of the tree, green on the top 1/3 only (see Picture 1). Most all the other trees look good from my side of the property line, so far. There is evidence of two other trees similarly beginning to turn brown from the bottom…but ONLY on the other side of the property line. The trees are on a gentle slope and the area drains well after rain. Occasinal hand watering when dry in the summers. 10-10-10 applied early fall 2018. Close to an area where lime on fescue grass was applied also in the fall. I have included pictures. I am worried as I see a few locations on Rte 2 near Owings where 1/2 of thirty beautiful Leyland (or similar species) are turning brown, some much worse than mine and completely brown. I am in zip code 20639. Pictures included. I can send more pix if needed. I noticed this in mid-Nov…it seems to be progressing slowly. Is the one 1/2 brown tree going to infect the others? Is this a fungus or insect problem? Should it be pruned where the brown is? Completely Removed? Spray something on it? Wait till Spring? Thank you very much for your consideration.

Why Are My Leyland Cypress Trees Turning Yellow?

Leyland cypress is fast-growing and easy to maintain. Given good conditions, it quickly grows into a thick screen, providing privacy and shelter from winds. It also makes a pretty specimen tree. As easy as they are to grow, Leylands sometimes hit a bump in the road and turn yellow. Yellowing needles on a Leyland cypress often indicate chlorosis. Close attention to soil conditions will both prevent and cure chlorosis in Leyland cypress.


The leaves of Leyland cypress should be a dark forest green and the needles should have a waxy texture. Affected plants turn yellow-green–inside needles turning first–then completely yellow. If untreated, growth stops, followed by continued decline and death.

Soil pH

Chlorosis is caused by iron deficiency. Iron, present in most garden soils, is not available to plants unless soil pH is correct. Leyland cypress prefers acidic soil, but is tolerant of most alkaline soils. Still, soil pH of 7.5 or greater can block iron absorption in Leylands.


Leyland cypress should be planted in well-drained soil with neutral to acidic pH–5.0 to 6.5 is ideal. Soils above 7.50 should be amended with iron sulphate or aluminum sulphate to increase acidity.


Treat affected plants by scratching iron sulphate or aluminum sulphate into the soil above the roots. Adding in 1 inch of compost to soils at this time will enrich soil, providing moderate alkalinity and a medium for safely scratching supplements into the soil without disturbing roots. To quickly green-up yellowing Leylands, spray with a chelated iron solution according to label directions.


Replenish your Leyland with mulch every year, and let fallen needles decompose in places where they will nourish roots and contribute acidity to soil. Apply a fertilizer in late fall that has micronutrients and is formulated for acid-loving evergreens. Apply iron supplements to soil as soon as the needles begin to turn yellow.

Alternative Diagnosis

Yellow leaves on Leyland Cypress can sometimes be caused by too much water. Soil should never be waterlogged and should be left to dry before irrigation. Leylands planted in wet soils will continue to fail and die, so transplant them to a more suitable location.

Q: Three out of my twenty seven Leyland cypress’s are dead and most of the others have branches turning brown. Is there chemical that will stop this?

A: This is a common situation during and after a drought (and after severe cold).

Leyland cypress has thin bark which splits easily in dry or cold weather. The splits admit various damaging fungi. The most common is seridium canker. The canker encircles an infected twig and causes the needles beyond that point to die.

You can see the canker damage if you skin back the bark with a pocket knife.

There are no fungicides to control this disease. The best thing you can do is to prune out dead branches and spray rubbing alcohol on your pruning tool between each cut. You can also sterilize by filling a small bucket with 1:10 bleach:water and dipping the pruner head into the bucket after each cut.

In the future, remember that Leyland cypress is a shallowly rooted plant. Water it deeply once each week if the soil becomes dry.

canker damage on branch

Tags For This Article: disease, drought, pruning, tools

The beauty of having an evergreen tree is that, while other trees are turning brown and shriveling up during the autumn and winter months, they remain vibrant all year round.

Evergreen trees are noted for their beauty and because they remain green throughout the year, they have earned fame as a symbol of winter. But you may have noticed that your evergreen tree isn’t so green anymore; maybe it’s losing its luster and even turning brown. Not limited to the winter months, this may happen during any season of the year (and in fact, you’ll often notice it in the spring after a particularly cold winter.) If that’s the case, why is it happening? And is it possible to fix an evergreen tree that is slowly turning brown? This article will try to give you a few tips about what to do if this happens to you.

Why is the tree turning brown?

Before you can take any steps to fix the problem, you need to figure out why your tree is turning brown. Actually, there are numerous reasons why an evergreen might start turning brown. There are a number of diseases that could be the culprit; there could also be a problem due to a lack of nutrition in the soil. There’s also the possibility that the tree is not getting access to the water that it needs. This could also be due to a number of reasons.

During the winter, the soil often gets so cold that the water in the ground freezes. When it does, the tree isn’t able to access the water and the needles begin to turn brown. This is also known as leaf burn or desiccation. If you notice leaf burn on your evergreen tree, the very first step you will need to take is to diagnose the problem.

The easiest way to do that is to secure the help of a tree service. If you live in Portland or the surrounding area, contact us here at Mr. Tree. Our arborists or tree surgeons will arrive to diagnose the issue and help suggest steps you can take to correct the problem.

What to do if it’s disease

Ultimately, if your tree looks sickly or is turning brown, the cause is usually lack of access to water and nutrients. The causes of this lack of water and nutrition, however, can vary wildly.

There are a number of different tree diseases that can affect the circulatory system of your tree, plugging up the vascular system that transports water from one area to the next. Generally, these diseases will start in one small area and spread from there. Needless to say, it’s always best to arrest the spread of the disease early if you can.

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Root rot is an example of an illness that evergreen trees are particularly susceptible to. In addition to brown, wilted needles, you will see what appear to be sores or cankers running along the root system of the tree, and if you remove any bark you will notice the wood beneath it becomes soft and brown. Root rot is caused by a fungus that can thrive in overly damp conditions. Fixing the tree requires digging the damp soil away from the rotting roots and allowing them to dry for a while.

Another common disease among evergreen trees is known as rust. This is another fungal disease which causes powdery fungal spores to appear on the needles; if this occurs, you will need to have the infected needles and branches pruned off. You can attempt to do this yourself, however, we recommend securing the help of a tree service, as we will be able to prune your tree in such a way that causes minimal stress to the branches that are still healthy.

What to do if it’s caused by weather

Besides disease, another major cause of evergreens browning is the weather conditions. The ground freezing in the wintertime can restrict the tree’s access to crucial water and nutrients that it normally draws from the soil.

While the tree is attempting to access water, it will be losing moisture through the needles and this will ultimately lead to dehydration. It can seriously damage, and in severe cases, even kill the tree. Solving the problem involves ensuring the tree has plenty of access to water.

In areas where a severe winter is expected, thoroughly watering during the warmer months can help to prevent leaf burn once it gets cold. Another cause of damage to evergreen trees that can cause browning during the wintertime is due to animals chewing on the branches as they seek food during the sparse winter months.

You may need to take steps to protect your tree from animals if you have problems with pests such as deer, rats, or other creatures. Ask your local tree service about steps you can take, such as wrapping your tree during wintertime to ward off unwelcome visitors.

Making your tree healthy again

While there are plenty of causes of tree browning, fixing the tree ultimately boils down to two things: prevention and maintenance. Preventing browning is the first step that you can take by following the directions above. If that doesn’t work, call us up at Mr. Tree to assist you.

While it is possible to prune your tree and otherwise care for it yourself, we don’t recommend it as professional arborists are highly trained in what they do and are able to do it in such a way as to not only maximize the health of the tree, but also help to ensure the safety of their workers, your home, and your family.

With professional inspections and care, you will be able to keep your evergreen tree a beautiful rich green color throughout the entire year!

Tagged as: brown tree, Dying Tree, is my tree dying, why is my tree brown

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