Smoulder
Botrytis narcissicola
What is Smoulder (Botrytis narcissicola)?
Smoulder is a fungal disease caused by the fungus Botrytis narcissicola (previously Sclerotinia narcissicola) which targets narcissus plants. It can persist in the soil and on infected bulbs for several years. This disease is more commonly observed in regions with cool and wet climates. In the spring, the initial signs of smoulder manifest as dark brown-black tips on the emerging shoots. These shoots often exhibit withered, distorted, and blackened leaf tips. If left untreated, the disease can spread throughout the entire plant, leading to yellowing and death of the leaves.
How does Smoulder (Botrytis narcissicola) occur?
Botrytis narcissicola reproduces through the formation of black resting bodies called sclerotia in the neck and outer papery scales of infected daffodil bulbs. These sclerotia serve as a source of infection. The fungus also produces mycelium in the bulb neck. When infected bulbs grow and leaves emerge through the neck, the fungus infects the leaves, leading to primary symptoms. Sclerotia in leaf debris and soil can also result in primary symptoms when shoots push through infested soil. Cool and wet conditions promote the development and spread of the disease.
Symptoms
1 - Impact on Plants
Botrytis narcissicola can cause yellowing and death of leaves, while infected flowers may experience distortion and discoloration.
2 - Soil Health
• Persistent Fungus: Botrytis narcissicola can survive in the soil for several years, leading to recurring infections. • Impact on Plant Health: The presence of the fungus in the soil can affect the overall health of susceptible plants.
3 - Impact on Environment
• High prevalence of the disease can impact the population and diversity • Reduction in bulb and flower quality can have economic implications for growers and nurseries.
Solutions
1 - Prevention
1. Well-Drained Soil: Plant in soil with good drainage to avoid excess moisture. 2. Avoid Disease-Prone Areas: Steer clear of planting daffodils in areas where smoulder has been a problem previously. 3. Use Resistant Varieties: Choose plant varieties known for resisting Botrytis narcissicola. 4. Remove Infected Bulbs: Promptly remove and destroy any infected bulbs to prevent disease spread.
2 - Chemical Treatment
Common fungicides for controlling smoulder (Botrytis narcissicola) in daffodils and other infected plants include benomyl, carbendazim, chlorothalonil, iprodione, mancozeb, metiram, propiconazole, tebuconazole, and vinclozolin, which can be applied as sprays or drenches, It is important to follow label instructions to ensure daffodil safety.
