Survival of Diaporthe phaseolorum var. caulivora (causal agent of soybean stem canker) artificially inoculated in different crop residues

Abstract

Stem canker caused by Diaporthe phaseolorum var. caulivora is an important disease of soybean in Argentina. The objective of this study was to determine its survival ability in artificially infested straw under laboratory and field conditions. In laboratory, stem pieces of soybean, maize, sorghum, sunflower, potato and wheat were autoclaved, placed in petri dishes on Potato Dextrose Agar and Water Agar, and inoculated with a 7-day-old pathogen culture. All crop residues were colonized and produced perithecia. Debris artificially infested with D. phaseolorum var. caulivora were placed in plastic net bags and transferred to an un-cropped area in a field plot at the University of Buenos Aires. Straws were left on the ground from winter to spring season in both 2007 and 2008 years. After 6 months abundant perithecia were developed in all straws. However, a higher number of perithecia on soybean and sunflower compared to maize, sorghum and potato was determined. These findings suggest that other crops, besides soybean, could maintain alive the inoculum of Diaporthe phaseolorum var. caulivora from soybean for at least 6-7 months.

Analysis of the species spectrum of the Diaporthe/Phomopsis complex in European soybean seeds

“…caulivora did not reproduce asexually in this study. However, the same finding had been already reported in Argentina (Grijalba and Ridao 2012). Albeit it is also observed that D. caulivora can seldom produce pycnidia (Santos et al 2011).…”

Soybean Stem Canker Caused by Diaporthe caulivora; Pathogen Diversity, Colonization Process, and Plant Defense Activation

“…Consistently, trichomes are preferred penetration sites for several fungi, facilitating adhesion of fungal spores and hyphae, and allowing fungal colonization progress on the tissue surface (Lazniewska et al, 2012). Ascospores on infected soybean and crop residue are the main source of inoculum (Grijalba and Ridao, 2012), and our results suggest that hyphae from germinated ascospores could be associated with trichomes. After inoculation, D. caulivora started to colonize the cortex at 24 hpi, progressed, and reached the phloem at 48 hpi and the xylem at 72 hpi.…”

“…In 2002, D. caulivora was widely disseminated in the main soybeanproducing region of Argentina, where it coexists with D. aspalathi (Pioli et al, 2002). At present, D. caulivora is considered the predominant pathogen causing SSC in Argentina (Grijalba and Guillin, 2007;Grijalba and Ridao, 2012). The high number of D. caulivora isolates in soybean stems with canker lesions also suggests the dissemination of this pathogen in Uruguay.…”

First Report of a Postharvest Fruit Rot on Apple Caused by <i>Diaporthe phaseolorum</i> var. <i>caulivora</i> in China: A Note

“…The ascospores cause the first infections of young stems in spring and all subsequent infections. The fungus could maintain alive in hosts for at least 6-7 months [12]. On susceptible varieties, it can cause losses of up to 50% of the hosts.…”