The Most Common Bald Cypress Tree Diseases: Identification and Treatment

The bald cypress tree, with its beautiful knobby knees and graceful draping foliage, is a favorite ornamental tree in landscapes across much of the eastern and southeastern United States. Unfortunately, like all trees, bald cypresses can fall victim to various diseases that may disfigure or even kill them if left unchecked.

As a bald cypress owner, it’s important to learn how to identify the most common cypress tree afflictions so you can try to treat them early and save your tree. This guide will walk you through the symptoms, causes, and treatment options for the top bald cypress tree diseases. Read on to become a tree doctor!

Fungal Diseases of Bald Cypress Trees

A number of fungal diseases are capable of infecting bald cypress trees. These include cankers, root rots, needle casts, and rusts. Fungal diseases thrive in wet, humid conditions.

Cankers

Cankers are areas on the tree’s bark or branches where fungus has killed the tissue. Cankers often start small but expand over time, girdling and killing branches. Three canker diseases impact bald cypresses:

• Phomopsis Canker – Caused by the fungus Phomopsis juniperovora, this canker disease creates sunken, elongated dead areas on branches and stems. The centers later become cracked and invaded by other fungi.

• Seiridium Canker – Seiridium unicorne fungus infects cypresses injured by storms, sunscald, pruning cuts, etc Cankers ooze reddish resin and slowly girdle branches.

• Strumella Canker – Strumella coryneoidea fungus infects bark causing elongated sunken cankers that ooze foul-smelling reddish-brown resin.

To treat cankers, prune out infected branches at least 6 inches below visible symptoms. Remove and destroy debris to prevent spread. Avoid unnecessary injury to trees. Fungicides generally aren’t effective.

Root Rots

Root rot fungi such as Armillaria Ganoderma and Phytophthora attack bald cypress roots, interrupting the tree’s ability to transport water and nutrients. Trees with root rot decline slowly, often wilting and dropping leaves/needles during summer droughts. Diagnose by digging near tree base to check roots for fungal growth, resin bleeding, and death.

Improve drainage around affected trees. Remove and destroy dead roots. Fungicide soil drenches can suppress Armillaria and Phytophthora. Ganoderma is difficult to control once established.

Needle Casts

Needle cast fungal diseases cause premature needle loss in bald cypress. Major diseases include:

• Phomopsis Twig and Needle Blight – Diseased needles turn reddish-brown before dropping. Dieback occurs on severely infected branches. Phomopsis juniperovora fungus overwinters on debris.

• Mycosphaerella Leaf Spot and Needle Cast – Mycosphaerella thujina fungus causes purplish-black spots on leaves. Needles turn yellow and fall off. Attacks stressed trees.

• Cercospora Needle Blight – Olive-green bands encircle needles, which then turn reddish-brown and drop off. Caused by Pseudocercospora sequoiae-juniperi.

Improve tree vigor with proper care. Rake up and dispose of fallen needles/leaves to reduce fungal inoculum. Apply fungicides at budbreak to protect new foliage. Repeat every 7-14 days until conditions no longer favor disease.

Rust Diseases

Rust fungi attack leaves and twigs. Symptoms are yellow/white powdery spores erupting from undersides of infected plant parts. Main bald cypress rusts:

• Gulf Cypress Cone Rust – Cronartium strobilinum fungus causes young cones to turn into rounded rust “galls”. Galls burst open and release spores. Disease is minor, mainly cosmetic.

• Cypress Twig Rust – Uredinopsis mirabilissima fungus prompts twig dieback when telial columns replace infected tissue. Prune out affected twigs.

Rust diseases are seldom serious enough on landscape cypresses to warrant control. Remove galls or infected twigs to improve appearance. Fungicides usually aren’t necessary.

Bald Cypress Bacterial Diseases

Bacteria can also cause diseases in bald cypress trees:

• Bacterial Leaf Scorch – Xylella fastidiosa bacteria block water movement in leaves, causing browning leaf margins and scorching. Affected trees decline over time. Manage scorch by reducing stress and pruning off 30% of canopy to decrease water demand. No cure exists.

• Bacterial Wetwood – Unidentified bacteria infect cypress trunks/branches through wounds, causing foul-smelling wet discoloration in wood. Weeping holes form in advanced cases. Manage by improving vigor and pruning outweepy areas. Keep wounds small when pruning.

Non-Infectious Bald Cypress Tree Problems

Abiotic disorders can also trouble bald cypresses:

• Sunscalding – Bark damage on exposed southern/western sides of younger trees due to extreme temperature fluctuations. Protect trunks with tree wrap.

• Herbicide Injury – Exposed roots absorb damaging weedkillers. Symptoms vary. Dig and remove contaminated soil near affected trees.

• Salt Injury – Salt used for icy roads damages exposed roots. Affected trees wilt and drop needles. Leach soil to remove salt if detected early.

• Nutrient Deficiencies – Yellowing leaves and stunted shoots indicate nitrogen shortage. Apply balanced fertilizer in early spring. Iron deficiency causes leaf yellowing between veins. Foliar iron sprays can help.

• Drought Stress – Bald cypresses are vulnerable to drought. Water deeply when top several inches of soil become dry. Mulch helps conserve moisture.

Best Practices For Healthy Bald Cypress Trees

Here are a few tips to keep your bald cypress healthy and ward off diseases:

• Select disease-resistant cultivars like ‘Shawnee Brave’ and ‘Choctaw’. Avoid cultivars prone to cankers like ‘Debbie’s Compact’.

• Give trees plenty of room – don’t plant too close together. Improves airflow and lowers humidity.

• Water young trees during dry periods for establishment. Irrigate mature trees during severe or prolonged drought.

• Apply 2-3 inches of natural mulch around trees, keeping it 6 inches from trunks. Mulch conserves moisture and cools root zones.

• Prune properly in late winter, making clean cuts just outside branch collars. Keep pruning tools disinfected. Avoid unnecessary wounding.

• Check trees periodically for early disease symptoms and treat promptly. Early detection and removal of infections improves control.

• Rake up and dispose of diseased leaves/needles and fallen cones to reduce fungal inoculum levels.

When To Call A Professional

Contact a certified arborist if:

• A tree has extensive dieback, limb loss, or canopy thinning.

• You are unsure about the disease diagnosis or proper treatment.

• The tree is in noticeable decline over multiple years.

• Cankers, wetwood, or root rots cover extensive areas.

• Pruning cannot remove all infected areas.

The sooner severe bald cypress tree diseases and problems are professionally diagnosed and addressed, the better your chances of saving the tree. Don’t delay!

With some awareness and attentive care, you can keep your bald cypress trees thriving for years to come in a landscape setting. Know the most common cypress afflictions, check frequently for symptoms, and take prompt action at the first sign of disease. removing any infected plant material. Your efforts will be rewarded with many years of enjoyment of this captivating and iconic southern tree.