Rosemary Dieback from Rhizoctonia: Pruning and Cultural Management

Rosemary Dieback from Rhizoctonia: Pruning and Cultural Management

Brown, dead patches in the center of 2-year-old rosemary plants each summer indicate Rhizoctonia fungal dieback. The fungus thrives in humid, poorly ventilated centers and on stressed plants.

Management

• Prune out affected branches as soon as seen; do not wait.
• If in pots, repot in fresh, sterile potting mix.
• Ensure excellent air circulation; space plants widely.
• Avoid overhead watering; keep foliage dry.
• Improve drainage with gritty soil mix.

Rhizoctonia is ubiquitous in soil; cultural management is more sustainable than fungicides.