The Okame cherry tree (Prunus x incamp ‘Okame’) is a prized ornamental tree celebrated for its early-season display of rosy-pink blossoms. This hybrid, derived from Prunus incisa and Prunus campanulata, is favored for its compact size, upright growth habit, and tolerance for heat and cold. It thrives across USDA Hardiness Zones 6 through 9.
Its ability to bloom in late winter or very early spring provides color before other trees begin to awaken. Although generally robust, the Okame cherry is susceptible to common pest and disease issues affecting the Prunus family, especially when under environmental stress. Identifying these problems and implementing targeted cultural care is the most effective way to maintain the tree’s health and ensure a reliable bloom display.
Insect Pests Targeting Okame Cherry Trees
Several small, sap-feeding insects threaten the health and appearance of Okame cherry trees. Identification relies on visual cues and the resulting damage.
Aphids are tiny, soft-bodied pests that cluster densely on new growth, primarily on the undersides of leaves and young stems. Their feeding causes leaves to curl and distort. They excrete honeydew, a sugary waste product, which often leads to black sooty mold on branches and leaves. A strong spray of water can dislodge light populations, while heavier infestations respond well to insecticidal soap or neem oil, which must contact the insects directly.
Scale insects appear as small, immobile, shell-like bumps fixed to the bark of branches or twigs. These insects suck plant sap, leading to branch dieback and a decline in tree vigor. Managing scale is often accomplished using a horticultural oil applied during the dormant season, which smothers the overwintering pests.
Borers, such as the peach tree borer, are a serious threat because they tunnel into the wood just beneath the bark. They often target weakened or stressed trees. Signs of infestation include fine sawdust-like material called frass, or the oozing of sap (gummosis) near entry holes in the trunk or major limbs. Preventative measures are the most reliable defense, including maintaining tree health and avoiding mechanical injury. Once borers are established, treatment may require a targeted insecticide application or the physical removal of larvae using a flexible wire.
Common Fungal and Bacterial Tree Diseases
Cankers are a common concern for Prunus species, especially Cytospora canker, which is prevalent when the Okame cherry is stressed by drought, poor drainage, or winter injury.
This fungal disease is characterized by sunken, dead areas on the bark of branches or the trunk, often accompanied by gummosis. The fungus typically invades the tree only through existing wounds or compromised tissue, eventually girdling and killing the branch. Management involves pruning out infected branches several inches below the visible canker margin during dry weather, ensuring all tools are sanitized afterward.
Shot hole disease results in small, round holes in the leaves, appearing as if peppered with buckshot. This symptom can be caused by the fungus Blumeriella jaapii or the bacterium Xanthomonas pruni, both favoring warm, wet spring conditions. The pathogen initially creates reddish-brown spots. As the infected tissue dies, it falls away, leaving the characteristic hole.
Cultural control involves raking and disposing of fallen leaves in autumn to reduce overwintering pathogen material. Severe fungal infections may be mitigated with preventative fungicide sprays applied as new leaves emerge, while bactericides are required for the bacterial form.
Powdery mildew is a fungal issue that manifests as a white or grayish, dusty coating on the upper surface of the leaves. It typically occurs during periods of high humidity and poor air circulation. This disease rarely kills the tree but can weaken it. It is best managed by pruning to open up the canopy and allow for better airflow.
Environmental Stressors and Cultural Care Mistakes
The Okame cherry’s health and capacity to bloom are sensitive to its environment and care, with improper planting and watering often leading to decline.
Planting the tree too deeply, which buries the root flare—the point where the trunk widens at the soil line—can lead to root suffocation, stunted growth, and eventual root rot. The tree requires well-draining soil and will suffer in heavy clay or overly wet conditions, exhibiting yellowing leaves and a general lack of vigor due to chronic water stress.
Lack of flowering, or a reduction in bloom, is often traced back to improper pruning timing or cold injury. The Okame cherry sets its flower buds for the following year shortly after the current season’s bloom. Pruning the tree in late summer, fall, or winter removes these developing flower buds. Pruning should be limited to immediately after the petals fall in the spring to preserve the next season’s display, or during the dormant season for structural cuts, accepting the loss of some blooms.
Young trees are susceptible to sunscald, a form of winter injury where the bark on the south or southwest side of the trunk cracks and splits due to rapid temperature fluctuations. This damage occurs when the sun warms the dark bark during the day, causing cell activity, followed by a sharp freeze at night that ruptures the tissue. Wrapping the trunk of a young tree with a commercial tree wrap in late fall, or painting the trunk with a white, reflective interior latex paint, can help equalize the temperature and prevent this common wound. This wound is a prime entry point for canker pathogens and borers.