Skip Laurel (Prunus laurocerasus ‘Schipkaensis’) is a favored evergreen shrub, valued for its dense foliage and adaptability in various landscapes. It is often used for privacy screens or hedges, maintaining its green color year-round. However, yellowing leaves, known as chlorosis, indicate an underlying issue that can usually be identified and corrected.
Understanding Why Skip Laurel Leaves Turn Yellow
Several factors can contribute to yellowing Skip Laurel leaves, from environmental conditions to specific deficiencies or biological issues. Each cause affects the plant’s physiology in distinct ways, leading to the visible symptom of chlorosis. Understanding these mechanisms is the first step toward restoring the plant’s health.
Watering Imbalances
Watering imbalances, both overwatering and underwatering, can cause yellowing. Overwatering suffocates roots by displacing essential oxygen in the soil, leading to root rot, which impairs the plant’s ability to absorb water and nutrients. Leaves may yellow and wilt despite wet soil. Underwatering stresses the plant, hindering moisture and nutrient uptake, causing leaves to yellow and become crispy.
Nutrient Deficiencies
Yellowing can indicate a lack of specific nutrients essential for chlorophyll production. Iron deficiency causes interveinal chlorosis, where areas between leaf veins turn yellow while veins remain green. A lack of magnesium also results in interveinal yellowing, appearing on older leaves, sometimes with reddish blotches. Nitrogen deficiency leads to a uniform yellowing of entire leaves, starting with older foliage.
Soil pH Issues
Soil pH influences nutrient availability. Skip Laurels prefer a soil pH range between 6.0 and 7.5. If the soil pH is too high (alkaline) or too low (acidic) outside this optimal range, certain nutrients can become unavailable to roots. For example, iron absorption is reduced in overly alkaline soils.
Environmental Stress
Environmental stressors can trigger yellowing. Extreme temperature fluctuations, like cold snaps or heatwaves, can shock the plant. Transplant shock can also cause temporary yellowing. Insufficient sunlight can also contribute to discoloration.
Pests and Diseases
Pests and diseases can cause yellowing. Sap-sucking insects like scale extract vital sap, leading to yellowing and decline. Fungal diseases such as root rot attack the root system, inhibiting water and nutrient transport, causing leaves to yellow and drop.
Diagnosing the Specific Cause
Diagnosing yellowing involves observation and testing. Examine the yellowing pattern: uniform yellowing on older leaves suggests nitrogen deficiency, while yellowing between veins on new leaves points to iron deficiency. Check soil moisture by inserting your finger 4 to 6 inches into the soil; excessively wet soil indicates overwatering, while very dry soil suggests underwatering.
Inspect for pests, webbing, or unusual spots. Consider recent weather or care changes. A soil test provides definitive pH and nutrient information.
Effective Solutions for Yellow Leaves
Once the cause is identified, targeted solutions can restore health. For watering imbalances, adjust your schedule to allow soil to dry slightly between deep waterings. Improve drainage by incorporating organic matter or creating raised beds.
Address nutrient deficiencies with specific amendments. Iron chelate can be applied for iron deficiency, especially in alkaline soils. For general needs, use a balanced, slow-release fertilizer. To correct soil pH, add sulfur to lower pH or lime to raise it, based on soil test recommendations.
Protect from environmental stress with shelter from extreme weather. When transplanting, minimize root disturbance and water thoroughly. Manage pests and diseases with horticultural oils or appropriate fungicides, following instructions carefully.
Preventing Future Yellowing
Long-term care prevents future yellowing. Ensure proper planting: dig a wide hole for the root ball, plant at the correct depth, and ensure good soil contact.
Consistent, deep watering is key; established plants need thorough watering when the top few inches of soil are dry, not frequent shallow watering. Regular, balanced fertilization, guided by soil tests, ensures necessary nutrients without over-application.
Routinely inspect for early signs of pests or diseases, allowing prompt intervention. Choose a planting location with suitable light and well-draining soil from the outset.