EFFECT OF EXPOSURE OF POTATO TUBERS TO VOLATILE COMPOUNDS ON Rhizoctonia solani AND Ralstonia solanacearum TRANSMITTED BY TUBERS

Abstract

Potato tubers infected with Rhizoctonia solani and Ralstonia solanacearm, the causal organisms of black scurfand bacterial wiltdiseases were obtained from store-houses and fields at different areas in Egypt.The pathogenswere isolated from infected potato tubers and identified.Tubers were treated with the volatile compounds (methanol , ethanol , amyl alcohol , formic acid , acetic acid , propionic acid , gasmonic acid , formaldehyde , acetaldehyde , chloroform , acetone) in fumigation chamber (2.3 L) at different levels. Results indicated that formaldehyde , formic acid , acetic acid and propionic acid showed high reductive effect on mycelial growth of Rhizoctonia solani from treated sclerotia on water agar medium. Formaldehyde and acetic acid showed eradicative effect on latent infection of Ralstonia solanacearm.However, these compoundsshowed no harmful effect on potato tubers sprouting when potato tubers were fumigated by 2.5 µl / l air space for 60 min.