Dry rot
Stromatinia gladioli
What is Dry rot (Stromatinia gladioli)?
Stromatinia gladioli is a soilborne fungus capable of surviving for over 10 years. It forms dormant sclerotia that remain inactive until stimulated by nearby gladiolus roots. Found in cool, wet climates, it affects gladiolus, daffodils, and freesias. Symptoms include small brown lesions on leaves and corms, leading to wilting and leaf death. Dry rot poses a major threat to global gladiolus crops, persisting for years and thriving during the active growth season in cool, wet climates. Controlling this fungus is challenging due to its long soil persistence, increasing the risk of infection.
How does Dry rot (Stromatinia gladioli) occur?
Stromatinia gladioli reproduce through the production of sclerotia, which are compact masses of fungal mycelium. These sclerotia can survive in the soil for extended periods. When gladiolus roots are nearby, the sclerotia germinate and produce spores. The spores are then dispersed through various means, such as wind, water, or soil movement. If the spores come into contact with susceptible hosts, they can initiate infection. The fungus enters the leaves and stems, causing dry rot and eventually leading to plant death.
Symptoms
1 - Impact on Flowers
Stromatinia gladioli negatively affect plants by causing a range of issues, including reduced flower quality and appearance, stunted and distorted flower growth, failure to bloom or limited flower production, as well as wilting, yellowing, and ultimately the death of leaves.
2 - Impacts on Soil Health and the Environment
• Stromatinia gladioli infestation brings economic losses for farmers and gardeners and environmental implications from fungicide use. • It adversely affects gladiolus cultivation and productivity, with the pathogen persisting in the soil for extended periods. This increases the risk of future infections, reduces plant success, and poses a potential reservoir for the fungus.
Solutions
1 - Preventions
• Planting in Well-Drained Soil: Ensure that the soil has good drainage to minimize excess moisture, which can promote fungal growth and disease development. • Crop Rotation: Rotate gladiolus crops with different types of plants each year to reduce the buildup of fungal pathogens in the soil. • Using Certified Disease-Free Corms: Start with high-quality, certified disease-free gladiolus corms to minimize the risk of introducing the fungus.
2 - Chemical Control
Various fungicides such as azoxystrobin, thiophanate-methyl, chlorothalonil, mancozeb, propiconazole, and difenoconazole are available for controlling fungal diseases like dry rot caused by Stromatinia gladioli. Specific selection and usage should be based on the disease, stage of infection, and local regulations.
