Tulip Fire Disease: How to Identify and Control It

Tulip fire — caused by the fungal pathogen Botrytis tulipae — is the most destructive disease of tulips in cool, wet climates. Its name comes from the scorched appearance of affected leaves and flowers, which look as though they have been singed by a flame. Left unchecked, the disease can devastate an entire planting in a single season and persist in the soil for years.

How to Identify Tulip Fire

Symptoms vary depending on when the disease strikes. Infected shoots emerging from the ground may be distorted, twisted or covered in small brown lesions. On leaves and petals, look for oval or rounded brown spots with a paler centre — the classic "fire" marking. In humid conditions a grey, velvety mould (the Botrytis spore mass) develops on affected tissue. Flowers may fail to open fully or develop brown streaks and patches across the petals. In severe infections, stems collapse at or near the soil surface.

Conditions That Favour the Disease

Botrytis tulipae thrives in cool, wet, humid conditions — exactly the spring weather that tulips prefer. High plant density, poor air circulation and overhead watering all create microclimates that allow the fungus to spread rapidly. The pathogen overwinters as sclerotia (small, hard resting bodies) on infected plant debris or in the soil, producing spores the following spring that are carried by wind and rain splash to new hosts.

Control and Prevention

Remove and destroy all infected plant material immediately — do not compost it. After the foliage dies back completely, lift bulbs and inspect them carefully. Discard any that show brown rotted patches or the characteristic small, dark sclerotia on the outer scales. Dust clean bulbs with sulphur powder or a thiram-based bulb dip before storing. Do not replant tulips in the same bed for at least three years, as sclerotia persist in soil. Improving soil drainage and spacing plants well to improve air movement both reduce disease risk.

Fungicide Options

In areas with a history of tulip fire, preventive fungicide applications can be used. Products containing mancozeb, chlorothalonil (where available) or tebuconazole applied from shoot emergence and repeated every 10–14 days during cool, wet spring weather reduce infection. Always read the label and follow application rates. Fungicides are most effective when combined with good cultural practices — they cannot compensate for overcrowding, waterlogged soil or leaving infected debris in place.

Bulb Treatment at Planting

Inspect bulbs at purchase and at planting for any signs of discolouration or soft spots on the outer scales. Planting only clean, firm bulbs reduces the inoculum introduced to new beds. Some growers dust bulbs with sulphur or a proprietary bulb fungicide before planting as a standard precaution in gardens with a history of the disease. Avoid damaging the outer scales during handling, as wounds are easy entry points for Botrytis spores.