Tulips, daffodils, or other bulb plants that develop stunted, yellowed leaves, or fail to emerge in the spring may be suffering from bulb rot. Cool, soggy conditions can favor infection by certain soilborne plant pathogens. Several different fungi and bacteria may infect bulb tissue.
These microorganisms often gain entrance through wounds created by insects or improper handling of the bulbs. Extended periods of wet weather favor infection. Diagnosis of below-ground problems involves hands-on investigation. Symptomatic plants need to be dug and examined. Diseased bulbs usually are discolored, soft, and may emit a foul odor. In some cases, there may be a black or bluish mold on the bulbs.
Diseased bulbs should be discarded, along with some of the surrounding soil. The best way to prevent the occurrence of bulb rots is to make the sure the planting site is prepared so it will be well drained. Avoid planting in areas that are poorly drained or that collect water.
To minimize convenient entry points for pathogens, take care to avoid wounding when handling bulbs. Buy from a reputable source and examine bulbs for any bruises or other damage. Plant at the proper depth, encourage good air circulation, and manage water needs. Plants that are growing vigorously are best able to resist diseases.
This article originally appeared in the 5/9/2003 issue.