Canker Disease Treatments by SavATree Insects & Diseases Canker diseases are fungal or bacterial infections that cause localized dead areas on tree bark, branches, and trunks. These open wounds weaken trees, making them vulnerable to environmental stress. If left untreated, cankers can interrupt the tree’s ability to move nutrients from the leaves to the roots, leading to decline or death. At SavATree, our ISA Certified Arborists specialize in diagnosing and treating tree diseases and cankers. We use science-backed strategies to manage infections and improve tree health whenever possible. What Causes Cankers and How Do They Spread? Cankers are caused by fungal pathogens (e.g. Botryosphaeria, Nectria, Cytospora) or bacteria (e.g. Pseudomonas). Many fungal spores live in soil, fallen leaves, or dead wood. Other fungi, such as Cytospora, operate like sleeper cells, spending the winter in bark or plant debris and releasing spores in the spring. These pathogens typically invade trees through open wounds like pruning cuts, insect damage, sunscald, and more. For this reason, stressed trees—such as those impacted by drought—are more vulnerable to infection. Canker-causing fungi and bacteria also spread from infected trees to nearby trees through wind, rain, insects, or unsterilized pruning tools. Arborist Tip: Avoid pruning in wet weather to minimize the chances of spreading spores and disinfect your tools between cuts. Signs of Canker Disease Wondering if your trees are showing signs of canker disease? Early detection is key to helping infected trees. Look for these symptoms to get a better understanding of what’s happening on your property: 1. Cytospora Canker Sunken, orange-brown lesions on branches White resin or sap oozing (common in spruce & peach trees) Dead branches with needles/leaves turning brown Commonly Effects: Colorado blue spruce, other spruces, peach, apricot, cherry, and other stone fruits, poplar, aspen, and willow 2. Nectria Canker Swollen, cracked bark with dark margins Bright red or pink fungal spores in wet weather Twig dieback in maples, dogwoods, and honey locust Commonly Effects: Apple, pear, honey locust, sugar maple, birch, beech, and ash 3. Botryosphaeria Canker Dark, sunken patches on bark Black speckles (fungal spores) inside cracks Sudden wilting in stressed trees (ash, juniper, redbud) Commonly Effects: A wide range of stressed trees and shrubs including oak, elm, apple, rhododendron, ash, juniper, redbud, grapevine, and azalea 4. Hypoxylon Canker Yellow-then-gray peeling bark (oaks, sycamores) Powdery tan/brown spores under bark Rapid crown thinning before tree death Unfortunately, these cankers have no known cure, and the only treatment is removal. Commonly Effects: Oaks (especially in the red oak group), sycamore, planetree, and aspen If you see these symptoms, give your ISA Certified Arborist a call and schedule your free consultation. Early treatment can make the difference when treating cankers on your property. Are your trees showing different symptoms? Your landscape may be affected by another disease or insect. SavATree offers comprehensive insect management and tree care to identify and treat various tree health issues. Life Cycle of Canker Diseases Canker pathogens follow a seasonal rhythm. While the exact timing may vary by region and pathogen, this general cycle helps guide detection and treatment strategies: Spring & Fall – Infection Season Fungal and bacterial pathogens enter through wounds caused by pruning, insects, or weather damage. Moist conditions during these seasons make trees more vulnerable. Summer – Internal Spread Once inside the tree, pathogens thrive beneath the bark. The tree may show no external symptoms yet, but this is the beginning of cankers forming. Fall & Winter – Canker Expansion As the tree slows for dormancy, infected tissues continue to die. This is when visible cankers may form, especially near wounds or where branches meet. Late Winter to Early Spring – Spore Release During wet and warming weather, spores are released and spread to nearby trees by wind, rain, or insects. Year-Round – Tree Decline Once the pathogens that cause cankers invade your tree, they slowly disrupt nutrient flow, which may weaken or kill the tree over time. Where to Find Canker Disease Treatment Near You If you're searching for “oozing black spots on my tree,” “why is tree bark cracked,” or “canker disease treatment near me,” SavATree can help. Our ISA Certified Arborists provide customized care to stop the spread of canker diseases and improve tree health. Depending on the type and severity of infection, we may recommend precision pruning to safely remove diseased limbs, targeted treatments (where applicable), or soil health improvements like aeration and fertilization to strengthen stressed trees. Schedule a free consultation with SavATree and take the first step toward protecting your property from the pathogens that cause cankers. Contact us today to schedule a consultation with an expert arborist.