Rhizoctonia Blight of Azolla japonica Caused by Rhizoctonia solani

Lee, Jung Han; Cha, Jea Yul; Noh, Gil Han; Han, Ki Soo; Bae, Dong Won; Kwon, Young Sang; Lim, Chae Shin; Jeong, Sung Woo; Kwon, Jin Hyeuk; Park, Chung Gyoo; Kwa, Youn Sig

Research in Plant Disease 2011;17(3):405-409.
Published online December 30, 2011.

Rhizoctonia solani에 의한 큰물개구리밥(Azolla japonica) 마름병

이정한, 차재율, 노길한, 한기수, 배동원, 권영상, 임채신, 정성우, 권진혁, 박정규, 곽연식

Rhizoctonia Blight of Azolla japonica Caused by Rhizoctonia solani

Jung Han Lee, Jea Yul Cha, Gil Han Noh, Ki Soo Han, Dong Won Bae, Young Sang Kwon, Chae Shin Lim, Sung Woo Jeong, Jin Hyeuk Kwon, Chung Gyoo Park, Youn Sig Kwa

Abstract

Azolla Lam. is a small aquatic fern with deeply bilobed leaves, which are consisted of a thick greenish, with chlorophyll, upper (dorsal) lobe and a thinner, translucent lower (ventral) lobe, without chlorophyll, submerged in the water. Azolla blight was observed at a lotus pond. Mycological characteristics of the fungus associated with Azolla blight was immediately determined as Rhizoctonia sp. by the thickness and branching of hypha at right angles at the point toward the distal end of septa, with branching hypha is constricted. The fungus produced brown mycelia and dark brown sclerotia on PDA. The optimum temperature for mycelial growth and sclerotia formation were 25oC and 30oC, respectively. The optimum temperature for fungal infection was 30oC, when spray inoculated. Phylogenetic analysis of rDNA-ITS revealed that the fungus was identified as Rhizoctonia solani (AG-1 IA) closest to one causing rice sheath blight disease. This is the first report on the blight disease of Azolla caused by R. solani in Korea.

Key Words: Azolla japonica, Green manure plants, Rhizoctonia solani