TULIP BREAKING VIRUS, THE ONLY CAUSE OF 'BROWN RING FORMATION' IN LILIUM MID-CENTURY HYBRID 'ENCHANTMENT'

Three isolates of tulip breaking virus (TBV), causing full-, self-and average break symptoms in the petals of infected 'Rose Copland' tulips (van Slogteren, 1971), had been maintained in Lilium formosanum seedlings. By means of aphids (Myzus persicae) each isolate was transmitted to separate virus-free plants of Lilium Mid-Century hybrid 'Enchantment' grown under glass at 20°C.

The symptoms in the leaves and in the bulb scales of the 'Enchantment' lilies inoculated with either the full- or the self-break isolate of TBV were characteristic for the disease called 'brown ring formation' (Asjes et al., 1973). The plants however inoculated with the average break isolate not only showed symptoms in the leaves but also in the flower (bud)s. Moreover upon lifting the bulbs showed dark brown spots at the tip and the base of the outer scales and after storage of the bulbs for 3 months at 2°C brown concentric rings on all the scales.

In a preceding experiment after inoculation with the three TBV-isolates, 'Enchantment' lilies which already carried lily symptomless virus (LSV) had exhibited the same respective symptoms as were shown by the originally virus-free lilies.

Thus it is concluded that TBV is the only cause of the 'brown ring formation' disease in Lilium Mid-Century hybrid 'Enchantment', and that the presence of LSV is not required.