Suppression of Fusarium wilt of spinach with hypovirulent binucleate Rhizoctonia

摘要

Four isolates of hypovirulent binucleate Rhizoctonia (HBNR) were evaluated for their ability to control Fusarium wilt of spinach (FWS) caused by Fusarium oxyspomm f. sp. spinaciae (FOS). Fourteen-day-old spinach seedlings grown in paper pots with HBNR-amended soil (1 percent w/w ground barley grain inoculum) were transferred to artificially pathogen-infested soil. Treatments with HBNR isolates significantly (P = 0.05) reduced disease and discoloration severity by 56 percent-100 percent and 52 percent-100 percent, respectively. The numbers of coloay-forming units of FOS per gram fresh weight in petioles or roots were reduced significantly (P = 0.01) in the plants treated with HBNR. HBNR isolates were well reisolated from the roots inside paper potswhere they were inoculated, whereas inconsistent colonization of HBNR was recorded from the roots outside paper pots where only pathogen was inoculated. Root extracts from HBNR-treated and pathogen-challenged plants significantly inhibited germination and germling length of FOS. The fresh weight of spinach leaves in the HBNR-treated plants increased significantly (P = 0.01), as much as 53 percent-63 percent, over the untreated and pathogen-challenged plants. This is the first report of biocontrol of FWS by HBNR.