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ARS Home » Southeast Area » Mayaguez, Puerto Rico » Tropical Crops and Germplasm Research » Research » Publications at this Location » Publication #274136

Title: Identification of soil-borne pathogens in a common bean root rot nursery in Isabela, Puerto Rico

Author
item Porch, Timothy - Tim
item Valentin, Suheidy - University Of Puerto Rico
item Beaver, James - University Of Puerto Rico

Submitted to: Journal of Agriculture of the University of Puerto Rico
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2014
Publication Date: 5/2/2014
Citation: Porch Clay, T.G., Valentin, S., Beaver, J. 2014. Identification of soil-borne pathogens in a common bean root rot nursery in Isabela, Puerto Rico. Journal of Agriculture of the University of Puerto Rico. 98:1-14.

Interpretive Summary: Limited research has been completed on the root rot complex of the common bean in the Caribbean, while yield losses of over 50% due to root rot disease have been reported worldwide. In this study, the predominant root rot pathogens in a 40-year old common bean root rot field in Isabela, Puerto Rico were identified over three planting seasons. The most prevalent pathogens identified were Fusarium spp., of which Fusarium solani causes Fusarium root rot and Fusarium oxysporum causes Fusarium wilt; Macrophomina phaseolina, which causes charcoal rot; and Sclerotium spp., of which Sclerotium rolfsii causes Southern blight. Other fungi were isolated from root and hypocotyl tissue with less frequency. The incidence of the predominant soil-borne pathogens varied among seasons. In addition, poor soil fertility conditions, specifically low nitrogen, phosphorus, and potassium in leaf tissue, were identified in the nursery. Knowledge of the prevalence of soil borne pathogens will be used for targeting the selection of breeding materials in the Isabela nursery and in other testing locations.

Technical Abstract: Limited research has been completed on the root rot complex of the common bean (Phaseolus vulgaris L.) in the Caribbean, while yield losses of over 50% due to root rot disease have been reported worldwide. In this study, the predominant root rot pathogens in a 40-year old common bean root rot nursery in Isabela, Puerto Rico were identified using standard diagnostic techniques over three planting seasons. The most prevalent pathogens identified were Fusarium spp., of which Fusarium solani causes Fusarium root rot and Fusarium oxysporum causes Fusarium wilt; Macrophomina phaseolina, which causes charcoal rot; and Sclerotium spp., of which Sclerotium rolfsii causes Southern blight. Other fungi were isolated from root and hypocotyl tissue with less frequency. The incidence of the predominant soil-borne pathogens varied among seasons. In addition, poor soil fertility conditions, specifically low nitrogen, phosphorus, and potassium in leaf tissue, were identified in the nursery. Knowledge of the prevalence of soil borne pathogens will be used for targeting the selection of breeding materials in the Isabela nursery and in other testing locations.