Damping-off of Edible Amaranth Caused by Rhizoctonia solani AG-4

Wan-Gyu Kim^1,* Hong-Sik Shim¹ Gyo-Bin Lee¹ Weon-Dae Cho¹

¹Global Agro-Consulting Corporation, Hwaseong 18330, Korea

Abstract

Damping-off symptoms were frequently observed on young plants of edible amaranth (Amaranthus mangostanus) grown in vinyl greenhouses by farmers located in Goyang and Yangpyeong in Korea during disease surveys carried out in 2019 and 2020. The incidence of the disease was 1−20%. A total of eight isolates of Rhizoctonia sp. were obtained from the stems of the diseased plants. All the isolates were identified as Rhizoctonia solani AG-4, based on the morphological characteristics and anastomosis test. Three isolates of R. solani AG-4 were tested for pathogenicity on edible amaranth by artificial inoculation. All the tested isolates of R. solani AG-4 induced damping-off symptoms on the inoculated plants; these symptoms were similar to those observed on the vinyl greenhouse plants surveyed. This is the first report of R. solani AG-4 causing damping-off in edible amaranth.

Figures & Tables

Fig. 1. Damping-off symptoms of edible amaranth and identification of the causal fungus, AG-4. A and B, dampingoff symptoms on edible amaranth plants observed in the vinyl greenhouse; C, anastomosis reactions between an isolate and tester isolate of AG-4; D, a colony of AG-4 isolate grown on PDA at 25℃ for 10 days; E, damping-off symptoms induced by artificial inoculation tests with AG-4 isolates. F, non-inoculated plants (control).