Occurrence Characteristics and Control Methods of Soft Rot in Lily Bulbs

Lily, a perennial herbaceous bulbous plant of the genus Lilium in the family Liliaceae, is mainly distributed in temperate regions of the Northern Hemisphere such as eastern Asia, Europe and North America. More than one hundred varieties have been found worldwide, and China is its most important center of origin, with more than fifty native species, making it the natural distribution center of the genus Lilium. In recent years there have been many new varieties produced through artificial hybridization, such as Asiatic lilies, trumpet lilies and fragrant lilies.

This disease occurs during the storage and transport of lily bulbs.

Symptoms: In the early stage of the disease, the affected scales develop water-soaked spots, which later turn dark brown, and the bulb softens and rots. In the late stage of the disease, a thick mold layer grows on the surface of the lesions, and within the mold layer many sporangia are produced that are first white and later turn black.

Pathogen: The pathogens are Rhizopus stolonifer (Ehrenb. ex Fr.) Vuill. and Rhizopus nigricans Ehrenb., belonging to the fungi of the subdivision Zygomycotina, class Zygomycetes, order Mucorales, genus Rhizopus.

Disease pattern: The pathogens are widely present in nature and invade the plant scales through wounds as sporangiospores, forming mycelium within the plant body. The mycelium can extend downward to the base of the scales and from there invade other scales. In warm, humid storage and transport environments with poor ventilation, the disease spreads rapidly and the bulbs rot quickly. The pathogens are weakly parasitic but highly pathogenic, and can cause the rot of many succulent vegetables, fruits and storage organs.

Control: Avoid causing wounds during harvesting, packaging, storage and transport; during storage and transport, low temperatures should be maintained.