Bacterial Soft Rot — Permaculture Database

Overview

Bacterial soft rot is caused mainly by Pectobacterium and Dickeya species that produce enzymes dissolving plant cell walls. It affects fleshy vegetables and ornamentals in the field, garden, and storage: potato, carrot, onion, brassicas, cucurbits, and many ornamentals. Warm temperatures and free moisture favor rapid breakdown. Wounds from insects, harvest tools, or hail create entry points. Soft rot often follows other diseases or mechanical injury and can turn a minor blemish into a foul-smelling mush overnight.

Symptoms

Infected tissue becomes water-soaked, soft, and sunken, then collapses into a slimy mass. A distinctive foul odor is common as secondary microbes join the rot. On potato tubers, soft rot may start at lenticels or wounds and progress inward. Stems and petioles can develop blackleg-like soft collapse in wet weather. Stored produce may look sound outside while soft inside. Flies and other insects are often attracted to rotting tissue.

Environmental Conditions

Humid

Prevention

Plant into well-drained beds and avoid overwatering fleshy crops near harvest. Control chewing insects that create wounds. Rotate crops and remove cull piles that harbor soft-rot bacteria. Sanitize harvest knives and storage containers. Store only sound, cured produce and check bins regularly for early soft spots. Choose cultivars with good storage quality for crops you plan to keep through winter.

Management

Remove and destroy rotting plants and produce promptly; do not leave them in beds or bins. Harvest carefully to minimize bruises, and cure crops such as onion and potato under appropriate conditions before long storage. Keep storage cool, dry, and well ventilated. Avoid washing produce into storage when wet surfaces encourage soft rot. In the field, improve drainage and reduce insect wounding. Copper sprays do little once soft rot is advanced inside tissue.