Tulips are stunning flowers that breathe fresh life into the spring garden. Unfortunately, their beauty is sometimes tarnished or destroyed by diseases and viruses. Thankfully, many tulip problems can be prevented, treated, and controlled.
Tulip Fire
One of the most devastating diseases affecting tulips is Tulip Fire, caused by the fungus Botrytis tulipae. The symptoms of tulip fire are vast and easy to spot. The newly emerging leaves may be distorted or twisted and will often wither away. If leaves do survive emergence, they will have small brown lesions that grow into large blighted scorched areas. Hence the common name
“Tulip Fire.” Often, small oval spots will appear on flower petals destroying the blooms appearance. During wet weather damaged leaves, stems, and flowers will become covered with a fuzzy, grey mycelial mat. Eventually, small black sclerotia, which is the resting structure of the fungus, may be found developing on the dead tissue. This fungus can persist on debris and in the soil for a long period of time.
Tulip Fire thrives in moist conditions, making it particularly problematic in regions with high humidity or frequent rainfall. The fungus can spread rapidly through splashing water, contaminated soil, or infected plant debris. Gardeners can reduce the risk of Tulip Fire by planting healthy tulip bulbs in well-drained soil, providing adequate air circulation, and avoiding overhead watering. If Tulip Fire is discovered the bulbs and plants must be discarded (not composted) and no tulips should be planted in the infected soil for at least 3 years.
Tulip Breaking Virus
Tulip Breaking Virus is transmitted by aphids and causes unexpected stripes, flecks, or featherings on tulip petals. It can also be spread mechanically. For example, transmission can occur when a healthy flower stem is cut with the same knife previously used to cut an infected stem. Thankfully, tulips with Tulip Breaking Virus do not die from the disease. Affected plants may be somewhat stunted and less vigorous. They will produce fewer offsets or bulbils, and their flowering is usually delayed by a week when compared to virus-free plants.
Control of TBV is straightforward. Dig up and destroy diseased plants and bulbs when broken flowers are discovered. This should be done before aphids feed and travel to nearby healthy tulips.
Tulip Basal Rot
Tulip Basal Rot is a fungal disease caused by Fusarium oxysporum f. sp. tulipae. Normally, fusariuminfection begins in the field and continues during postharvest storage. It can spread rapidly, especially in storage or during periods of high humidity.
Tulip bulbs infected with fusarium will have brown spots and white or pink fungal growth. The bulbs often feel very light and may develop a sour odor as the fungus breaks down plant tissue. Fusarium typically enters bulbs through wounds. Once inside the bulb, the fungus proliferates, causing extensive damage and reducing the bulb's viability.
Fusarium fungus also produces a large quantity of the plant hormone, ethylene. This ethylene can cause flower abortion, stunted growth, and reduced rooting. Fusarium infected bulbs continue to produce ethylene after planting and can injure nearby bulbs in containers or forcing crates. To prevent TBR, inspect bulbs upon delivery and discard any that show signs of fusarium infection.
Pythium Root Rot
Tulip bulbs with Pythium Root Rot will develop soft, gray spots with brown borders near the base of the bulb. The bulbs often have a strong odor and may be soft when squeezed. A tulip plant with root rot will have a dark brown, mushy root system. The plants often yellow before wilting, and the blossoms may fall off before opening. Root rot is often caused by the pathogen pythium which thrives in moist areas with poor drainage. Avoid root rot by only planting healthy bulbs in well-draining soil and avoid overcrowding them.
While tulip diseases aren’t completely avoidable, many steps can be taken to protect their health and the health of your garden. First, start with healthy, disease-free bulbs from a reputable supplier. Avoid planting bulbs that show signs of disease or decay. Choose a planting site with well-drained soil, provide good air circulation, and avoid overhead watering whenever possible. Avoid planting tulips in areas prone to standing water or excessive moisture. Remove and trash any infected plant material, including infected bulbs to prevent the spread of disease. Clean and disinfect tools between uses to avoid transmitting pathogens. Avoid overhead watering, which can promote the spread of fungal diseases. Instead, water at the base of the plant or provide drip irrigation to keep foliage dry and reduce moisture-related diseases.
