Sources of Inoculum and Management for Rhizoctonia solani Damping-off on Tobacco Transplants under Greenhouse Conditions

Abstract

Damping-off and target spot are important diseases of tobacco transplants produced under greenhouse conditions. Identification of sources of inoculum for these diseases caused by Rhizoctonia solani is an important first step in disease management. Control strategies based on sanitation and the eradication of primary inoculum were studied. Potting mix and Styrofoam trays used in transplant production were assayed to determine if they were sources of primary inoculum. Eleven sources of potting mix were sampled over a 2-year period. None of the mixes contained viable inoculum of R. solani. R. solani was isolated from previously used trays after 1 year of storage by removing and plating pieces of Styrofoam from individual tray cells on alkaline water agar (AWA). Sclerotia and melanized hyphae of R. solani were observed in the cracks present in the cells of the trays. Dry heat (70 to 80°C for 2 h) and chemical (sodium hypochlorite and sodium chloride) treatments reduced the levels of inoculum on trays up to 45% compared to controls, but only methyl bromide and steam treatments (80°C for 0.5 to 2.0 h) eradicated inoculum of R. solani from trays. Elimination of primary inoculum from previously used trays effectively controlled target spot and stem rot diseases caused by R. solani.

Molecular identification and pathogenicity of Rhizoctonia spp. from tobacco growing areas in northwestern Argentina

“…Multiple AGs of R. solani are pathogenic on tobacco (Shew and Melton 1995;Nicoletti and Lahoz 1995;Gutierrez et al 1997;Nicoletti et al 1999;Zhao et al 2013). AG 1, AG 2-1, AG 2-2 and AG 4 cause root rot, stem rot or sore shin, and damping-off, while AG 2-1 and AG 3 cause target spot on leaves of tobacco (Shew and Melton 1995;Gutierrez et al 1997;Nicoletti et al 1999;Mercado Cárdenas et al 2012;Zhao et al 2013). In our study the R. solani isolates identified as AG 2-1 were obtained from plants with damping-off, target spot and sore shin symptoms.…”

“…Currently, 13 AGs have been reported , with many of the AGs further divided into subgroups based on DNA sequencing (Laroche et al 1992;Johnk and Jones 1993;Tu et al 1996;Carling 1996;Sharon et al 2008;González García 2008). Isolates of AG 1, AG 2-2, AG 4 and AG 5 cause damping-off and sore shin of tobacco (Gutierrez et al 1997;Nicoletti and Lahoz 1995), whereas isolates of AG 3 cause target spot (Shew and Melton 1995;Zhao et al 2013). Recently, binucleate (BN) Rhizoctonia AG-A, AG-F, AG-G, AG-P, AG-R have also been reported as the cause of damping-off in tobacco (Masuka 1998;Garcia et al 2009;Gurkanli and Ozkoc 2011).…”

Genetic structure of populations ofRhizoctonia solaniAG-3 on potato in eastern North Carolina

“…Samples were assayed on alkaline water agar (AWA, pH 8.5) to isolate R. solani AG-3 PT (Gutierrez et al 1997). A total of 104 pure cultures of R. solani were established by transferring mycelium from single hyphal tips to potato dextrose agar.…”

Uji Antagonisme Bacillus cereus terhadap Rhizoctonia solani dan Sclerotium rolfsii

“…Ketika kondisi lingkungan mendukung bagi pertumbuhannya maka sklerosia tersebut akan berkecambah dan jika menemukan inang yang sesuai, hifa yang berasal dari perkecambahan sklerosia dapat menginfeksi tanaman inang yang ada. Tanaman yang dapat menjadi inang kedua jamur tersebut sangat banyak baik, dari kelompok tanaman hortikultura, seperti sayuran dan tanaman hias; kelompok tanaman perkebunan seperti kapas, tembakau, wijen, bunga matahari; maupun tanaman pangan seperti padi, jagung, kedelai, kacang hijau, dan sebagainya (Gutierrez et al 1997;Yulianti & Ibrahim 2000;Ceresini et al 2002;Muis & Quimio 2006;Gurkanli & Ozkoc 2011).…”