C-VIRAL DISEASE

 

C-Viral Diseases

Gandy and Hollings (1962) were the first to demonstrate the association .of three types of 'viruses in mushrooms. Since then, viral diseases have been reported throughout the world on different mushrooms. In India, virus and virus-like disease have been reported on button mushroom (Tewari and Singh, 1984, 1985; Goltapeh and Kapoor, 1990). However, detailed information on symptoms, epidemiology, and losses caused transmission and control measures of button mushroom viruses are discussed below.

Causal Organism:Several viruses of different shapes and sizes have been reported. In India, viruses have been found associated with a virus disease of button mushroom (Tewari and Singh, 1984, 1985). Virus-like particles measuring 29 nm in diameter have also been reported on button mushroom (Goltapeh and Kapoor, 1990).

Symptoms:-The various names coined for mushroom viruses give some indication of the diversity and variation of symptoms1nducecl by viruses in mushrooms. Symptom expression depends upon virus concentration; time of infection, strain of the spawn used and cultural and environmental conditions. The common symptoms observed are as below: - Pin heads appear late and sometimes below the surface of casing layer. If the sporophores appear above the casing layer, their pile is already opened. Mycelium isolated from diseased sporophores on agar shows a slow and degenerated growth as compared with healthy mycelium. Symptoms on sporophores are highly variable. The following abnormalities can be found separately or in combination:

·         Watery stripes or streaking in the stripe.

·         Dwarfing and Slow development of the pin heads.

·         Elongated and slightly bent stripes.

·         Early maturity with Off-white color of the caps

Epidemiology:There is no information’s about the incidence of viruses in mushrooms and losses caused by them in India but studies carried out and found that when virus inoculations were done 0 to 12 days after spawning, the extent of 'loss varied from 37.5 to 95.5 per cent over un-inoculated l (Dieleman van Zaayen, 1972).

Control:Hygienic measures are to be followed strictly. When virus-infected cultures are grown at 33⁰C for 2 weeks and hyphal tips then sub­ cultured and retimed to 25⁰C, the newly obtained cultures are generally free from viruses.