Mushroom virus disease in the Netherlands : symptoms, etiology, electron microscopy, spread and control

During the 1960s, Dutch mushroom farmers suffered severe losses from an infectious disease. Three types of virus particles were associated with the disease: isometric particles 25 and 34 run in diameter and bacilliform particles 19 run wide and 50 nm long. Symptoms were highly variable. Two, possibly three types of particle, were demonstrated in ultrathin sections of diseased fruiting bodies; one type, the 34-nm particle, was observed in sections of virus-infected mycelium from a nutrient medium and of basidiospores from diseased mushrooms.The disease spread with viable mycelium and spores from infected mushrooms. The time of infection governed loss of yield: earlier infection considerably reduced yield, whereas later infection did not. Results of the trials were used in drawing up control measures, which have been implemented among Dutch growers and have considerably reduced national losses, as shown by annual returns from the growers

Methyl bromide fumigation versus other ways to prevent the spread of mushroom virus disease

The treatments comprised methyl bromide (MB) fumigation v. 2% sodium pentachlorophenate (SPCP) treatment of wooden trays in which virus-infected mushrooms had been grown; MB v. formaldehyde fumigation of healthy and virus-infected spores and mycelium; and MB fumigation of compost permeated with virus-infected mushroom mycelium. MB fumigation of the trays did not eradicate virus in the subsequent crop, whereas SPCP treatment eliminated infection. Germination by diseased spores was almost completely inhibited by MB at low concentration time products and the growth of healthy spores was greatly retarded. Mycelium was not killed by MB but growth was retarded, as was that of mycelium from fumigated spawn. Formaldehyde treatment for 24 h killed spores and mycelium. MB fumigation of compost was ineffective. Thus MB fumigation cannot replace the traditional method of cooking-out mushroom houses with live steam, followed by treatment of the wood with SPCP. (Abstract retrieved from CAB Abstracts by CABI’s permission