First Report of Red Crown Rot Caused by Cylindrocladium parasiticum on Soybean in Guangdong, Southern China

Abstract

In October 2006, occurrence of a disease on soybean (Glycine max) was observed in Guangdong Province of southern China with symptoms resembling red crown rot (3,4). Reddish brown lesions girdled the basal stems with numerous reddish orange perithecia on the lesion surface. Roots became black and rotted and whole plants wilted and died. More recently, outbreaks of this disease were observed in several counties in Guangdong. Disease incidence reached as much as 80% on cv. Huaxia 3 in some fields, causing severe yield losses. Isolation was made from the edge of lesions on potato dextrose agar at 25°C. The fungus produced white, aerial mycelia and a burnt orange-to-dark brown submerged growth. Conidiophores were borne laterally on a stipe, terminating in a hyaline, globose vesicle measuring 4.0 to 13.0 μm in diameter. After branching from the stipe, the conidiophore continued to develop by forming two to three single-celled branches. These cells might give rise to two or three shorter branches (14.8 to 36.9 μm long) and phialides. The phialides were doliform, nonseptate, and measured 7.4 to 19.7 × 3.7 to 4.9 μm. Conidia were hyaline, cylindrical with one to three septa (mostly three septa), and measured 54.1 to 76.3 × 4.9 to 7.4 μm. Perithecia were orange to red, subglobose to oval or globose, 212.1 to 454.5 μm high, and 111.1 to 333.3 μm wide. Asci were hyaline, clavate, thin walled, long stalked, measured 121.0 to 200.8 × 11.5 to 25.6 μm, and each contained eight ascospores that became aggregated in the upper half of the ascus at maturity. The ascospores were hyaline, fusoid to falcate with one to three septa (mostly with one septum), constricted slightly at the septum, and measured 29.5 to 73.8 × 4.9 to 9.8 μm. The fungus was identified as Cylindrocladium parasiticum (teleomorph Calonectria ilicicola) (1,2). The beta-tubulin gene fragment sequences of three isolates were obtained (one sequence being GenBank Accession No. GU073284) and comparisons with GenBank showed 99 to 100% similarity with Calonectria ilicicola (EF159730 and AY725643). Pathogenicity was confirmed by inoculation of 2-week-old seedlings of cv. Huaxia 3 in plastic pots (10 × 9 cm) by drenching with a conidia suspension (105 conidia per ml). All inoculated plants showed similar red crown rot symptoms on stem bases and roots 1 week after inoculation. C. parasiticum was reisolated from the diseased plants, and many orange-to-red perithecia of Calonectria ilicicola were formed on the lesions 3 weeks after inoculation. This pathogen may pose a serious threat to >300,000 ha of soybean production as well as >300,000 ha of peanut production in Guangdong Province. It has been previously reported in Jiangsu Province in eastern China (3) and Yunnan Province in western China (4). References: (1) D. K. Bell, and E. K. Sobers. Phytopathology 56:1361, 1966. (2) P. W. Crous et al. Mycol. Res. 97:889, 1993. (3) J. Y. Gai et al. Soybean Sci. (in Chinese) 11:113, 1992. (4) Z. H. Ma et al. Plant Pathol. 53:537, 2004.

Two novel species of Calonectria isolated from soil in a natural forest in China

“…ilicicola, which causes black rot (CBR) of Arachis hypogaea (peanut) and Medicago sativa (Gai et al 2012, Pei et al 2015, Ca. ilicicola causes red crown rot of Glycine max (soybean) (Guan et al 2010), and Ca. colhounii and Ca.…”

Root Interactions in a Maize/Soybean Intercropping System Control Soybean Soil-Borne Disease, Red Crown Rot

“…One potential target for control through crop heterogeneity is red crown rot, which is one of the most severe soil-borne diseases for plants. It is caused by the fungus Cylindrocladium parasiticum ( C. parasiticum , teleomorph Calonectria ilicicola ) and is named after the reddish brown basal stalk tissue of infected plants [9] – [11] . This pathogen has a wide host range, and red crown rot has been found in many countries with severe crop losses possible throughout its distribution.…”

“…), an economically important host of red crown rot, is a major cash crop and has been planted world wide. In South China, estimates for soybean yield loss due to red crown rot range to as high as 50% [11] . At present, there are no effective pesticides to control red crown rot.…”

Co-Inoculation with Rhizobia and AMF Inhibited Soybean Red Crown Rot: From Field Study to Plant Defense-Related Gene Expression Analysis

“…The field site has been growing soybean since 2000. Soybean red crown rot caused by C. parasiticum was observed in this field in 2006 and its disease incidence reached to 80% [10]. And then, we combined sand culture and fungal pathogen incubation experiments as well as some important PR gene expression analysis to evaluate the possible physiological and molecular mechanisms of rhizobium and AMF inoculation on soybean red crow rot inhibition.…”