Sclerotinia dry rot of gladiolus

The causative agent of this disease is the ascomycete fungus Sclerotinia draytonii (synonym Botryotinia draytonii). This pathogen acts as a specialized parasite that triggers a condition commonly known as dry rot, affecting various bulbous plants, primarily gladiolus.

The primary host for this pathogen is the gladiolus plant. The fungus is capable of colonizing both the foliage and the corms. It survives in the soil and on infected crop residues through the formation of sclerotia, which are hard, resistant fungal structures capable of enduring unfavorable conditions.

Early symptoms appear as small, brownish, water-soaked spots on the leaves, which gradually expand. As the infection progresses to the corms, distinct sunken, dark lesions develop. Over time, these lesions harden, and the infected tissue becomes dry and mummified, often showing visible fungal growth.

Development of the disease is highly dependent on environmental conditions, particularly high humidity and moderate temperatures ranging from 15 to 20 degrees Celsius. Spread occurs via contaminated soil, infected planting stock, and fungal spores disseminated by water splashes and wind during the growing season.

The economic impact of this disease is significant, as it leads to poor plant growth, low-quality flowers, and severe losses of corm stocks during storage. In cases of high inoculum pressure, it can destroy entire collections if preventative measures are neglected.

• Treat corms with systemic fungicides before planting.
• Rotate crops to avoid planting gladiolus in infested soil for at least 4 years.
• Immediately rogue and destroy any symptomatic plants found in the field.
• Ensure excellent air circulation and low humidity during corm storage.
• Practice deep plowing after harvest to bury surface debris and sclerotia.