Dogwood trees are known for their beauty. Discovering their leaves turning brown and curling can be concerning. This guide explains why your dogwood might be struggling and how to support its health.
Common Reasons for Dogwood Leaves Turning Brown and Curling
Several factors can lead to dogwood leaves browning and curling.
Environmental conditions frequently cause browning and curling. Drought stress, often seen during prolonged dry spells or intense heat, causes leaves to dry out and curl inward as the tree struggles to transport enough water. Too much direct sun can lead to sunburn, resulting in brown, crispy leaf edges. Cold or frost damage can also cause leaves to brown and wilt when temperatures drop significantly.
Pest infestations can also cause leaf damage. Aphids are small insects that feed on tree sap, causing leaves to yellow and brown, often leaving sticky honeydew. Dogwood borers create holes in the trunk and branches, disrupting water and nutrient flow, which can lead to wilting, browning leaves, and premature leaf drop. Scale insects, appearing as small bumps on branches and leaves, feed on sap, weakening the tree and causing leaves to yellow and brown. Dogwood sawfly larvae consume leaf tissue, often skeletonizing leaves, which can then brown, curl, and fall off.
Fungal diseases are a common cause of leaf browning and curling. Dogwood anthracnose typically appears as brown spots with purple borders on leaves, leading to wilting, premature leaf drop, and twig dieback. This disease thrives in wet conditions. Powdery mildew presents as a white, powdery coating on leaves, which can cause yellowing, curling, and early leaf drop. Leaf spot diseases result in small, circular spots that can cause leaves to yellow and drop prematurely.
Nutrient deficiencies can lead to poor health and discoloration. Transplant shock often causes temporary browning and curling in recently planted dogwoods.
Identifying the Specific Issue
Observing specific symptoms and patterns can help pinpoint the exact problem affecting your dogwood.
Examine the pattern of damage on the leaves. If browning and curling are uniform across the tree, it often suggests a widespread issue like drought stress or heat scorch. Leaf scorch, characterized by browning along the edges and a wilted appearance, indicates water stress. If only certain branches or sections are affected, it might point to a localized problem such as a borer infestation or a canker disease.
Look closely for visible signs. Sticky residue on leaves and branches suggests aphids or scale insects. Small holes in the trunk or branches, often with sawdust-like frass, are signs of dogwood borers. A white, powdery film on the leaves indicates powdery mildew. Brown spots with distinct borders, particularly purplish margins, are characteristic of dogwood anthracnose.
Consider recent environmental conditions. If there has been a prolonged period without rain, drought stress is a likely cause. Conversely, excessive watering or poorly draining soil can also lead to leaf browning and curling. Newly planted trees are more prone to transplant shock, especially if not adequately watered after planting.
Effective Solutions and Treatments
Once the specific issue is identified, tailored solutions can help restore your dogwood’s health.
For drought-stressed trees, deep and slow watering is crucial. Apply water at the tree’s base, allowing it to penetrate deeply into the root zone, rather than frequent shallow watering. This encourages roots to grow deeper, making the tree more resilient to dry periods. Ensure the soil remains consistently moist but not waterlogged.
Pest management often starts with non-chemical methods. A strong spray of water can dislodge aphids and some scale insects. For dogwood borers, pruning and disposing of infested branches can help manage the population.
Managing fungal diseases like anthracnose and powdery mildew involves improving air circulation by selective pruning of dense branches. Raking and removing fallen leaves in autumn is also important, as these can harbor fungal spores. While fungicides exist, cultural practices often suffice for less severe infections.
If nutrient deficiency is suspected, a soil test can provide information on what your soil lacks. Based on results, appropriate fertilization can correct imbalances. For newly planted trees experiencing transplant shock, consistent and adequate watering is the most effective remedy.
Preventing Future Problems
Proactive measures and consistent care are key to maintaining a healthy dogwood tree and minimizing future issues.
Select a planting site with partial sun, especially afternoon shade in hotter climates, as dogwoods are understory trees and can suffer from excessive direct sunlight. Ensure the soil is well-drained and rich in organic matter, as dogwoods do not tolerate standing water. Plant with the top of the root ball slightly above or at soil level.
Consistent and adequate watering is fundamental, particularly during dry periods. Dogwoods have shallow root systems and benefit from regular moisture, especially in their first few years after planting. Aim for deep watering sessions rather than frequent, shallow ones, allowing the soil to dry slightly between waterings.
Applying a 3 to 4-inch layer of organic mulch, such as pine bark or shredded leaves, around the base of the tree helps retain soil moisture, regulate soil temperature, and suppress weeds. Keep the mulch a few inches away from the trunk to prevent moisture buildup and potential rot.
Promoting good air circulation through appropriate spacing and light pruning can reduce the incidence of fungal diseases. Regularly inspecting your dogwood for early signs of stress, pests, or disease allows for timely intervention before problems escalate. Choosing disease-resistant varieties can also reduce susceptibility to common issues like anthracnose and powdery mildew.