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United States Department of Agriculture

Agricultural Research Service

Title: Epiphytic Survival of Xanthomonas Axonopodis Pv. Allii and X. Axonopodis Pv. Phaseoli on Leguminous Hosts and Onion

Authors
item Gent, David
item Lang, Jillian - COLORADO STATE UNIVERSITY
item Schwartz, Howard - COLORADO STATE UNIVERSITY

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 5, 2004
Publication Date: N/A

Interpretive Summary: Xanthomonas leaf blight of onion and common bacterial blight of dry bean are perennial problems in the Central High Plains of the U.S., and are caused by two closely related pathogens. It is not known if these pathogens can survive on other hosts, but this may be important for disease management since onion and dry bean are commonly grown in rotation. In growth chamber studies favorable to the Xanthomonas leaf blight pathogen, the bacterium survived and multiplied on several common plant species, including alfalfa, chickpea, dry bean, lentil, and soybean, but the populations were at least 10-fold greater on onion. When artificially inoculated under field conditions, the bacterium was recovered from dry bean, lentil, and onion, but it did not persist on chickpea and soybean. The dry bean common bacterial blight pathogen was recovered from symptomless onion plants in fields cropped to dry bean the prior year, but not from fields cropped to a host other than dry bean. Close rotation of onion and dry bean may allow these pathogens to persist in the absence of disease symptoms, and these cropping systems may need to be altered to reduce survival of these pathogens and improve disease management.

Technical Abstract: Xanthomonas leaf blight of onion (caused by Xanthomonas axonopodis pv. allii) and common bacterial blight of dry bean (caused by Xanthomonas axonopodis pv. phaseoli) are perennial problems in the Central High Plains of the U.S. Onion and dry bean are commonly grown in rotation in Colorado, but it is unknown if X. axonopodis pv. allii and X. axonopodis pv. phaseoli survive epiphytically on dry bean and onion, respectively. Under high humidity growth chamber conditions, epiphytic X. axonopodis pv. allii populations increased on alfalfa, chickpea, dry bean, lentil, and soybean, but the epiphytic populations were at least 10-fold greater on onion. When artificially inoculated under field conditions, epiphytic populations of X. axonopodis pv. allii were recovered from dry bean, lentil, and onion, but the bacterium did not persist on chickpea and soybean. Epiphytic X. axonopodis pv. phaseoli was recovered from symptomless onion plants in fields cropped to dry bean the prior year, but not from fields cropped to a host other than dry bean. Close rotation of onion and dry bean may allow X. axonopodis pv. allii and X. axonopodis pv. phaseoli to persist epiphytically, and these cropping systems may need to be altered to reduce survival of these pathogens.

Last Modified: 10/20/2014
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