Three of the most common viruses affecting tulips are described
here.
Tulip breaking virus
Symptoms
This is the most commonly seen virus disease in tulips. It causes colour ‘breaking’ or streaking of the flower colour in pink, purple and red flowered tulips, but white and yellow flowered cultivars are not affected. It is particularly seen in late-flowering cultivars. Mottling or striping of the leaves also occurs. Other symptoms include loss of vigour and poor flower production.
While tulip breaking virus is now known to be undesirable due to the loss of vigour it causes, some ‘broken’ tulip flowers can look very spectacular. In the 17th century, when the craze for tulips was at its peak in Holland and the cause of flower breaking was unknown, bulbs producing broken flowers were extremely desirable and valuable. A single bulb was reported as being sold for the same price as a decent sized house! Any tulip cultivars with ‘broken’ flowers that can be bought today are the result of plant breeding rather than virus infection.
Biology
The disease is spread by several aphid species - Myzus persicae, Macrosiphum euphorbiae, and Aphis fabae.
Control
Control using insecticides is not very effective. Remove and destroy infected bulbs. Avoid planting tulips close to lilies, which may harbour the virus without visible symptoms.
Cucumber mosaic virus
This disease is also seen in late-flowering cultivars. Symptoms appear as grey-brown sunken spots or rings on the bulb scales, which appear in storage. These bulbs produce deformed plants with chlorotic lesions on the leaves and aborted or damaged flowers. The disease is spread by aphids and also affects many other plants. Removal of the bulbs is the only control.
Tobacco necrosis virus
This disease is also known as Augusta virus after the cultivar in which it was first detected. Early flowering cultivars are particularly prone.
Brown necrotic streaks appear on the leaves and stems. The virus is transmitted by a soil-inhabiting fungus Olpidium brassicae.
Remove and destroy affected plants and avoid replanting tulips on that site. Late planting in November also helps minimise infection.