Effect of acetic acid fumigation on soil-borne fungi and cucumber root rot disease under greenhouse conditions

Abstract

The effect of acetic acid vapour on soil-borne fungi and root rot disease of cucumber plants under greenhouse conditions was studied. Acetic acid vapour at four concentrations was tested against linear growth and spore germination of some soil-borne fungi, in vitro. The most sensitive fungus to acetic acid vapours was Rhizoctonia solani which inhibited at 4 µl l−1, while Fusarium solani, Fusarium oxysporium f. sp. cucumerinum, Scleroitium rolfsii and Didymella melonis inhibited at 6 µl l−1. Complete inhibition of spore germination was obtained with acetic acid vapours at 4 µl l−1 with all tested fungi. Acetic acid vapours significantly reduced germination of resting stage of all tested fungi. Complete inhibition of chlamedospores of F. solani and F. oxysporum f. sp. cucumerinum was obtained with acetic acid vapour at 10 µl l−1, meanwhile, sclerotia of S. rolfsii was killed at 20 µl l−1 of acetic acid vapour. Four types of soil: sandy, loamy, clay and peat-moss were fumigated with acetic acid vapour for 60 minutes. A higher response was recorded with peat-moss and sandy soil in which soil-borne fungi were inhibited at 75 and 100 µl l−1 respectively, while in loamy and clay soil fungi were inhibited at 125 µl l−1. Peat-moss soils were artificially infested with individual cucumber root rot fungi and fumigated with acetic acid vapour for 60 minutes. A population count of pathogenic fungi and cucumber root rot disease was carried out. Results indicated that acetic acid vapour at 75 µl l−1 caused a complete reduction in the population of cucumber root rot fungi and under greenhouse conditions it reduced the cucumber root rot disease more than 93.3 and 95.4% for pre- and post-emergence respectively. It could be suggested that acetic acid vapours might be safely used for controlling cucumber root rot disease under greenhouse conditions.