“Brusone” disease of rice in hungary

Summary

Brusone causes considerable damage in Hungary in years with cool, sunless summers. The disease only occurs on certain soil types. The observation, which has been made several times, that healthy and diseased plants may be separated in paddy fields along a straight line, together with histological and biochemical examinations, indicate that the brusone is a soil-borne physiological disease. It has been established by ecological observations and chemical, microbiological, meteorological, histological and physiological investigations that the primary cause of the disease is H₂S. This compound kills the roots of the rice plant. The occurrence of fungi (Piricularia, etc.) is merely a secondary phenomenon and is probably connected with disturbance of the nitrogen metabolism of the plant.

The formation of hydrogen sulphide and its toxic effect on the rice plant are promoted by several factors but especially by cool and sunless weather. In such weather the carbon assimilation of the paddy plant is reduced and the toxic H₂S in the soil is not transformed. In such circumstances the disease may cause disastrous damages to rice plants growing on those soils where the disease is particularly inclined to develop.