Leak

Pathogen: Pythium ultimum and other spp.s

Symptoms

Dark lesions that spread on and within the tuber and quickly turn to soft rot. A foul odor becomes apparent as other microorganisms begin to develop.

Damage

Complete rotting of the tuber during harvest and storage. Tubers are unusable for propagation. Soil contamination.

Conditions for Development

The pathogen becomes established in the soil by means of oospores (viable on plant residues), and inoculates by directly penetrating into wounds. Most inoculation occurs during the growing season, harvest and grading. Pathogen populations are transmitted in the soil by a variety of hosts (e.g. carrot, pea, peanut, etc.).

Control

Pesticides: Systemic chemicals for control of late blight are generally also effective against leak. If there has been no treatment administered for late blight, systemic fungicides may be applied at the end of the growing season. Soil fumigation may eradicate the pathogen in the soil.
Management: Proper drainage in the field, preventing delay of harvest, taking care not to wound tubers, keeping the storage area well ventilated.

Aerial Stem Rot
Black Dot, Colletotrichum coccodes
Blackleg and Tuber Soft Rot
Black Scurf, Rhizoctonia Canker
Common Scab, Streptomyces scabies
Early Blight, Alternaria solani
Deep Pitted Scab, Streptomyces spp
Leak, Pythium ultimum
PLRV, Potato Leafroll Virus
Powdery Scab, Spongospora subterranea
PVX, Potato Virus X
PVY, Potato Virus Y
Verticillium Wilt, Verticillium dahliae