Chrysantemum stunt viriod
English names: Stunt or measles of chrysantemum
Nordic names: Krysantemum dværgsygeviroid (DK)
Major host plants
Under natural conditions, CSVd has been identified in florists' chrysanthemums (Dendranthema morifolium) and related ornamentals such as Argyranthemum. All types of chrysanthemum can be infected with the CSVd but some are virtually symptomless
Symptoms can be variable and are highly dependent on both cultivar and environmental conditions, especially temperature and light. In many chrysanthemum cultivars, up to 30% of the infected plants are symptomless.
The symptoms of stunt disease may include the following:
- Stunting is the main symptom, with a reduction of between 30 and 50% in overall height of mature plants.
- Flowers bloom earlier than normal plants of the same cultivar.
- Flowers are fewer and smaller and the colour, particularly of the bronze and red ones, may be bleached to a lighter shade.
- Young foliage has a paler green colour and tends to be upright instead of curving away from the plant stems.
- Susceptible cultivars can develop “measles”, which appear as large, yellow leaf blotches. This symptom is restricted to certain old varieties and is rarely seen in natural-infected modern varieties.
- Cuttings that are infected by CSVd root poorly and may take up to five days longer than normal to root.
Chrysanthemum stunt was first identified in the USA. The viroid is now widespread due to international movement of cuttings.
A map can be downloaded fron EPPO's website. See instructions here.
The viroid is closely related to potato spindle tuber viroid. It appears unusually heat-stable and infectivity is retained in extracts treated with alcohol. In dry tissue, the viroid remains infectious for at least 2 years. The incubation period of the viroid in chrysanthemum is relatively long, from 2 to 3 months depending on the cultivar. Temperature and light intensity seem to play an important role in the development of the viroid in the plant.
The viroid is easily transmitted by tools and equipment used during cultivation, crop maintenance or harvest, and by contact between plants. Long distance spread occurs with shipment of infected cuttings or plants.
Detection and inspection
Visual detection based on symptoms is difficult. CSVd should therefore be confirmed in a laboratory with molecular technique.
Pest status and importance
Chrysanthemum stunt is a serious disease, which may have serious consequences for producers of chrysanthemums.
Source of information
See further information here:
Author: Christiane Scheel and Elise T. Yamamoto Buch
Editor: Dorthe Vestergaard