Longevity of Puccinia horiana teliospores under various environmental conditions

Authors: Bonde, Morris; PALMER, CRISTI - Rutgers University; Luster, Douglas - Doug; Nester, Susan; REVELL, JASON - Rutgers University; Berner, Dana

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2014
Publication Date: 3/18/2014
Publication URL: http://handle.nal.usda.gov/10113/58639
Citation: Bonde, M.R., Palmer, C.L., Luster, D.G., Nester, S.E., Revell, J., Berner, D.K. 2014. Longevity of Puccinia horiana teliospores under various environmental conditions. Plant Health Progress. doi: 10.1094/PHP-RS-13-0117.

Interpretive Summary: Puccinia horiana Henn. is a quarantine-significant fungal pathogen and causal agent of chrysanthemum white rust (CWR). The pathogen and disease were first discovered in the United States in 1977 and quickly eradicated. During the early 1990s, CWR re-emerged on several instances, but in each instance was declared eradicated. However, since approximately 2004, CWR has re-appeared with increased frequency. This has suggested that either P. horiana is entering the country more frequently from foreign locations, or that P. horiana is now established in the field, implying that spores are capable of surviving winter conditions in plant debris or soil. As a result of the possibility that the pathogen has become established in the U.S., we initiated several lines of research. The objectives of the study reported here were 1) develop a better and more sensitive method to measure spore longevity, and 2) determine if the pathogen has the capability to survive through northeastern winters as viable spores. Results from the study showed that spores of the fungal pathogen survived in the greenhouse a maximum of 28 days in dry soil and 7 days in moist soil. In a growth chamber simulating winter temperature conditions in the northeastern U.S., teliospores survived a maximum of 35 days. It was concluded that P. horiana teliospores are not able to survive through typical northeastern U.S. winters.

Technical Abstract: Puccinia horiana Henn. is a quarantine-significant fungal pathogen and causal agent of chrysanthemum white rust (CWR). The pathogen and disease were first discovered in the United States in 1977 and quickly eradicated. During the early 1990s, CWR re-emerged on several instances, but in each instance was declared eradicated. However, since approximately 2004, CWR has re-appeared with increased frequency. This has suggested that either P. horiana is entering the country more frequently from foreign locations, or that P. horiana is now established in the field, implying that spores are capable of surviving winter conditions in plant debris or soil. As a result of the possibility that the pathogen has become established in the U.S., we initiated several lines of research. The objectives of the study reported here were: 1) develop a better and more sensitive method to measure teliospore longevity, and 2) determine if the pathogen has the capability to survive through northeastern winters as viable teliospores. Results from the study showed that teliospores survived in the greenhouse a maximum of 28 days in dry soil and 7 days in moist soil. In a growth chamber simulating winter temperature conditions in northeastern U.S., teliospores survived a maximum of 35 days. It was concluded that P. horiana teliospores are not able to survive through typical northeastern U.S. winters.