Fire Blight in Tulips

Causal Agent

• Tulip fire blight disease is also known as botrytis blight. The fungal disease is caused by the plant-specific Botrytis tulipae pathogen. Fire blight is the most common and serious disorder of the plants that can cause severe loss of flowers. The fungus persists for extended periods in soil, continually affecting subsequent plantings.

Susceptibility

• All varieties of tulips, including hybrids, are susceptible to infection from the disease. Infection is usually more pronounced after frost or hail. The use of diseased bulbs is the most common cause of disease. Decaying debris from previous plantings also causes disease as the fruiting bodies in contaminated soil can infect new plants for up to two years. Spores germinate at temperatures ranging between 41 and 81 degrees Fahrenheit.

Symptoms

• The disease is characterized by the appearance of small, yellow, elongated spots with water-soaked margins on the foliage. The spots gradually get sunken in appearance and change to a white or gray. As infection progresses, the spots enlarge and merge to create large patches, also spreading to the flowers. Black fungal fruiting bodies are visible within the infected areas. Lesions start to rot through the stems and gradually the entire plants. Infected bulbs produce deformed and stunted plants.

Management

• Purchase healthy bulbs from reliable sources and practice three-year rotations of tulips in sites with known infection of the fungus. To reduce chances of infection, avoid planting tulips in any area more than once in three years. Remove bulbs within three weeks of petal fall and remove all stems from bulbs immediately. Minimize injury to bulbs during removal. Clear planting site of all debris. Chemical control options include the use of products containing thiophanate methyl, vinclozolin or ipridione.