Volume 7 Part 1 Article 16: An Investigation of X-Disease

Volume 7 Part 1 Article 16
Year 1969
Title: An Investigation of X-Disease
Author: R.A. Hager

Abstract:

X-disease a highly infectious disease of the cultivated mushroom, was observed on both the white and cream varieties. A golden white variety displaying typical La France symptoms was also studied.

The symptom expression of X-disease on both the white and cream varieties was quite variable. The most common and consistent symptom was the cessation of sporophore production usually accompanied by some sporophore distortion. La France symptoms were sporophore deformity and necrosis as well as mycelial death and reduced production.

Symptomatic expression of the X-diseased cream and the La France golden white isolates was more severe at cropping temperatures of 20–21°C than at 15–16°C. With all isolates, inoculations early in the crop produced more severe symptoms than later inoculations.

The mycelial isolates on agar were quite variable in symptomatology. The X-diseased cream and the La France golden white isolates appeared to be symptomless carriers, whereas the white X-disease isolate displayed symptoms typical of Mushroom Die-back isolates.

Electron microscopy revealed the presence of infectious 32 nm spheres in the white X-disease isolate obtained in sucrose gradient and differential ultracentnfugation as well as ultrasonic cellular disruption attempts, however specific antiserum could not be produced against these particles.

Electron microscopy of extracts from healthy mushrooms and healthy mushroom nucleoprotein did not reveal the presence of any defined particles. Evidence accumulated in this investigation indicates that X-disease of the white mushroom variety may be caused by a virus closely related to mushroom virus 2 isolated in Mushroom Die back studies although the evidence is not conclusive.

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