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United States Department of Agriculture

Agricultural Research Service

Title: Factors affecting infection of citrus with Xanthomonas axonopodis pv citri.

Authors
item Bock, Clive - UNIVERSITY OF FLORIDA
item Parker, P. E. - USDA, APHIS
item Cook, A. Z. - USDA, APHIS
item GOTTWALD, TIMOTHY

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 2006
Publication Date: June 1, 2006
Citation: Bock, C., Parker, P., Cook, A., Gottwald, T.R. 2006. Factors affecting infection of citrus with Xanthomonas axonopodis pv citri.. Phytopathology. 96(6):Supplement S14.

Technical Abstract: Xanthomonas axonopodis pv citri (Xac) causes citrus canker and is now considered endemic in Florida. Factors affecting dispersal and infection of the bacteria need to be understood to help optimize disease management strategies. Wind (0-18 m/sec) was simulated outdoors using a fan to study infection of citrus seedlings downwind from a source of sprayed inoculum. The effect of inoculum concentration (0-105 bacteria/ml), inoculation period (30 sec-15 min) and plant pretreatment (none, severe wind and spray for 30 min, and dew chamber conditions for 1.5 h) were investigated in relation to wind speeds (0-16 m/sec). Higher wind speed invariably resulted in more disease. Increased inoculum concentration resulted in greater incidence of infected leaves and lesions/infected leaf, as did duration of inoculum exposure. Exposure for 15 min resulted in 14.5 lesions/infected leaf compared to 4.8 lesions for 30 sec. A pretreatment of severe wind and spray for 30 min resulted in greatest disease (64% leaves infected compared to 47% for the control). Several factors influence the amount of disease developing subsequent to an infection event with Xac, and severe weather conditions not only disperse more inoculum, but stronger winds result in more infection per se during the event, and they also predispose plants to greater infection if they occur prior to the infection event.

Last Modified: 9/29/2014
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