The Spring Equinox has come and gone, which means only one thing. Spring has finally come! If you hadn’t already noticed the crocuses and daffodils popping up everywhere, when you start to see the splashes of red, orange, pink and purple which signal the arrival of the tulip, you’ll know. Speaking of riotous colours, have you ever wondered why tulips have crazy colours and patterns?
A lot of tulips are susceptible to a plant virus, called Tulip Breaking Virus. This virus infects the tulip bulbs before they come into flower. So when tulips flower, the petals show a variety of colour changes, stripes, flames and streaks. Infected tulips are then called ‘broken’ tulips. The intensity of these colour changes will depend on the age of the tulip bulb before it has sprouted, or the age of the flower when first infected, as well as the variety of tulip. There are two strains of the virus: Severe Tulip Breaking Virus and Mild Tulip Breaking Virus. Severe Tulip Breaking Virus will cause either full or light breaking. This means that the virus has stopped production of anthocyanin, a pigment found in the petals (and sometimes leaves) which results in red, purple or blue colouring. Lack of anthocyanin usually results in streaking and feathery patterns on the petals. Infection with Mild Tulip Breaking Virus causes an excess of anthocyanin production, resulting in petals with darker streaks, flecks or swirls. Although these colour changes and patterns make tulips more desirable, most ‘broken’ tulip lines no longer exist. This is because, over a period of time and tulip generations, the viral infection will cause the plant to slowly die, unable to pass on genetic information to future tulip generations.
Two of the most famous ‘broken’ tulips were the Semper Augustus and the Viceroy. They were grown during the Dutch Golden Age, when the prices of tulip bulbs rose rapidly, as demand grew. This period in time was also known as ‘Tulip Mania’. The public coveted these ‘broken’ tulips because they looked exotic, flamboyant and extravagant. As a result, the prices of these prized bulbs rose even further. Unfortunately these tulip lines don’t exist anymore.
A couple of the ways in which growers try to protect their tulips against this viral disease is by adding mineral oils to the soil, and spraying the tulips with insecticides. Spraying helps to deter aphids, which have been proven to help in the transmission of the virus. The aphids colonise the tulips and feed off the tulip sap, and at the same time the virus is transferred from the aphids’ saliva into the plant. These tulips are then stuck in a cycle of disease, but despite their vulnerability produce some of the most beautiful displays of colour.