|I planted three Mr. Goldstrike's last fall and this spring/summer the leaves started turning black on all three. What is causing this?|
|Aucuba japonica 'Mr. Goldstrike' is subject to several foliar diseases. Aucubas grow best in shaded areas. Plants growing in exposed areas may develop black leaf spots or blotches. A dieback characterized by total decay of leaves, petioles, and branches often occurs on exposed plants in early spring. This can be caused by exposure to full sun combined with cold injury. A weakly pathogenic fungus (Botryosphaeria sp.) is often found in such tissue and is common on many woody ornamental plants under environmental stress.
Significant dieback is often a sign that the plant may be under stress from root rot, crown rot, nematodes or other factors.
To control foliar problems, plant aucubas in partially shaded areas. Give exposed plants some protection during cold winter weather. Promptly prune out dead branches several inches below any sign of discoloration, and avoid excess fertilizer, especially during late summer and fall.
Best wishes with your landscape!