Cause Break is a disease name for any of several viruses including tulip breaking virus, tulip band-breaking virus, tulip top-breaking virus, Rembrandt tulip-breaking virus and lily mottle virus. Each is in the potyvirus group and is long flexuous rods. These viruses are spread by several species of aphids in a nonpersistent manner. They can also be mechanically transmitted in plant sap. Viruses survive in infected bulbs. White and yellow tulip cultivars generally do not show symptoms and thus may increase the risk that this disease will spread to other plants. Several other viruses have been reported to cause minor flower-breaking symptoms but flower and leaf symptoms are distinctly different.
The tulip cultivars Apeldoorn, Kees Nelis, and Lustige Witwe are susceptible, while cultivars Cantata, Juan, Madame Lefeber, and Priceps are resistant.
The symptoms were first described in tulips by Carolus Clusius in 1576. Bulbs producing variegated flowers were very desired and often sold for high prices, especially during the early seventeenth century. Tulips with variegated flowers were so rare and in such high demand that they created a wild speculation craze (tulipomania) which almost caused the collapse of the Dutch economy.
Symptoms Flower petals have stripes, streaks, feathering or flames of different colors. Symptoms vary with the flower cultivar, and age at time of infection. The color variation is related to the local accumulation of pigments in the upper epidermal layer. The lighter colors appear as irregular streaks or fine feathering. Dark breaking occurs when the color in the epidermal cells intensifies in small dark streaks or elongated flecks. The flame pattern appears as narrow or broad streaks of color in the center portion of the petal. Flames may also occur near petal edges. Flower size, pollen production and seed set are reduced. Over time vigor and flower quality of infected plants decline and bulbs gradually degenerate.
Easily confused with genetic variegation, which is readily available in commercial plants.
Cultural control Management is based on the prevention of infection by integrating many tactics.
- Routinely scout, remove, and destroy infected plants including volunteer plants from previous bulb crops.
- Purchase and plant virus-tested (and found to be free of known viruses) material.
- Exclude aphids with fine mesh screening.
- Harvest early to reduce exposure to increasing aphid populations.
- Disinfect cutting knives, containers, and equipment.
Chemical control Aphid control using insecticides has not prevented spread. Weekly applications of mineral oil have shown some efficacy. See the PNW Insect Management Handbook for details.
Reference Lesnaw, J.A. and Ghabrial, S.A. 2000. Tulip breaking: Past, present and future. Plant Disease 84:1052-1060.
McGovern, R.J., and Elmer, W.H. 2017. Diseases of Tulip. In McGovern, R.J. and Elmer, W.H. (eds.) Handbook of Florists' Crops Diseases. Springer Int.