Tulip Fire is a destructive fungal disease that attacks tulips, named because severe infections make the plants look scorched. It is recognized as the most common and damaging affliction of tulips wherever they are grown. This highly contagious condition can quickly spread through a tulip bed. Understanding the disease’s signs and spread is the first step in protecting your tulip garden.
Recognizing the Signs of Tulip Fire
The infection’s appearance changes depending on the plant part and the stage of the disease. Early signs may be visible as soon as shoots emerge, sometimes appearing twisted, withered, or failing to develop normally. These severely infected young shoots are often described as “fireheads” and are a primary source of fungal spread.
On mature leaves, characteristic symptoms are small, elongated spots that may look tan, yellow, or water-soaked. These spots quickly enlarge and turn brown, often leading to large, blighted areas that give the foliage a scorched look. In damp or humid conditions, a fuzzy, gray mold may grow over the dead tissue, indicating the fungus is actively producing spores.
Flowers are highly susceptible, showing small, oval spots or streaks on the petals that cause them to rot rapidly, especially in wet weather. Stems may also develop elongated, dark brown lesions, leading to distortion and sometimes complete collapse. Infected bulbs carry the disease over winter, exhibiting small, black, seed-like structures on the outer scales.
The Fungal Pathogen and Its Spread
Tulip Fire is caused by the fungus Botrytis tulipae, a pathogen closely related to the common gray mold. This fungus attacks all parts of the tulip plant and thrives in cool, moist conditions, making spring a high-risk period for infection. The fungus persists between growing seasons by forming small, dark resting bodies called sclerotia, which resemble pepper flakes.
Sclerotia are found on the outer scales of infected bulbs or can remain in the soil for at least two to three years. When conditions are right, the sclerotia germinate and infect new tulip shoots as they emerge. Once plants are growing, the primary means of transmission is through the microscopic spores produced by the fungus.
These fungal spores are easily spread by wind, splashing raindrops, or contaminated gardening tools and debris. Dropped flower petals can also facilitate new infection sites, especially in the leaf axils. Planting already infected bulbs is the most direct way to introduce the disease into a new garden bed.
Strategies for Control and Prevention
Preventing Tulip Fire begins with planting only healthy, inspected bulbs, discarding any that show signs of decay or the black sclerotia. Selecting a planting site with good drainage and ensuring adequate spacing between bulbs is important for maintaining air circulation. This helps reduce the high humidity levels that favor fungal growth and spore production.
Once the disease is confirmed, immediate action is necessary to halt its spread. The most effective control measure is the prompt removal and destruction of infected plants, including the entire bulb and any surrounding soil. This procedure, known as “rogueing,” must be done carefully to avoid shaking off fungal spores and contaminating adjacent plants.
Infected material should never be added to a compost pile, as the sclerotia can survive and re-infect new areas. If a site has experienced a severe outbreak, avoid replanting tulips in that location for at least three years to allow the fungus to die out. Chemical treatments are generally not a practical or recommended approach for home gardeners.