From Bill Miller, professor, Horticulture Section, School of Integrative Plant Science, Cornell University and director, Cornell Flower Bulb Research Program
This winter, we observed two very interesting natural phenomena while forcing thousands of flower bulbs for our trials at the Kenneth Post Laboratory Greenhouses.
Like most years, several of those forced tulips showed signs of tulip breaking virus (TBV). Technically, TBV is a disease. But one of the main symptoms is dramatic bloom color alterations including intricate bars, stripes, streaks, featherings or flame-like patterns.
This phenomenon contributed to the historic first collapse of a bubble economy, the famed Dutch “Tulip Mania” of the 17th century. Tulips with TBV helped fuel a speculative futures market, driving bulb prices to extraordinary levels. Single bulbs of coveted “broken” varieties commanded prices as high as 4,200 guilders at a time when a skilled craftsworker might earn 300 guilders a year.
Those prices are no longer with us since the bulb price crash of 1637. But TBV is – spread by aphids in the tulip production fields of Europe. Despite the spectacular blooms, the infection reduces the vigor and the size of plants and bulbs, and trade in broken bulbs is restricted to prevent widespread TBV outbreaks. But there are several varieties on the market with coloration that mimics the effects of the virus.
A tulip ‘thief’ at KPL
The second phenomenon we witnessed is exceptionally rare. In fact, in 22 years of bulb research and observing nearly 1 million tulips flowers, I’ve only seen it once before.
Amongst the normal blooms, we observed a small plant with a muddy-colored flower. The Dutch call this a “dief” – literally a thief.
These are actually ancient cultivars, usually with brownish-orange or brownish-pink flowers. It’s unlikely anyone ever selected for this germplasm with its mundane blooms. The plants are usually small and weak and rarely grow bulbs large enough to flower before they split.
They just sort of hitchhike along with other bulbs through the production cycle – unnoticed due to their lack of bloom and their bulbs that are indistinguishable from choice varieties – “stealing” space in the tulip grower’s field. Hence the nickname dief.
If a grower were to see one in their field, they would rogue it out. But for us, we had the rare treat: Forcing a single lot of bulbs that had a dief and TBV-induced breaking – as well as normal flowers.