Diagnosing Widespread Dieback in Red Apple Ice Plant Groundcover

Diagnosing Widespread Dieback in Red Apple Ice Plant Groundcover

Over 1/2 acre of red apple (Aptenia cordifolia, ice plant) on a California hillside started dying in summer 2015. Leaves turn brown, then vines die back. Open areas affected first. Drought conditions; watering doesn't help.

Possible Causes

• Natural lifespan: Ice plant may live only 2–3 years before needing replacement.
• Phytophthora root rot: Favored by wet, poorly drained soil. Unlikely in drought, but possible in low spots or if irrigation is uneven.
• Environmental stress: Extreme heat, reflected sun, poor soil, or nutrient depletion after many years.
• Herbicide drift: From nearby applications.

Diagnostic Steps

1. Dig up a symptomatic plant with roots. Check for brown/black rotten roots (Phytophthora).
2. Send sample to county extension lab for pathogen ID.
3. Check soil drainage—dig a hole, fill with water; should drain in <24 hrs.

Management

• If Phytophthora: improve drainage, remove dead plants, consider fungicide drench (mefenoxam) for remaining plants.
• If natural senescence: replant with fresh stock in amended soil.
• If environmental: amend soil with compost, ensure occasional deep watering, provide temporary shade during extreme heat.

Lab diagnosis is essential before large-scale replanting.