White mold is caused by a fungus. It typically attacks dead flower petals or dead leaves, then spreads into living tissues. The infection often starts in branch crotches or at the base of stems. Initial symptoms may include a rapidly spreading soft rot. Affected tissues turn gray and may be covered with a mass of cottony, white fungal growth. Hard, black fungal structures (measuring 1/4" to 1") are often produced on the cottony growth and inside the affected stems. Infected stems may be tan, then eventually turn a bleached, bone-like white. Disease development is favored by long periods of cool, wet weather.

Management Options

Non-Chemical Management

Plant in well-drained soils.
Avoid overhead irrigation.
Space plantings to improve air circulation, particularly around the base of the plants.

Select non-chemical management options as your first choice!

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides

None recommended

Images

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Caption: Interior stem showing white fungal growth and black sclerotia Photo by: R.S. Byther

WSU Extension

Hortsense