Xanthomonas

Evaluation of Disinfectant Seed Treatments to Reduce Xanthomonas hortorum pv. carotae in Carrot Seed Lots

Bacterial blight of carrot, caused by the plant pathogenic bacterium Xanthomonas hortorum pv. carotae (Xhc), is a common disease of carrot wherever the crop is grown. The disease can affect carrot foliage, stems, umbels, and roots and can be seed-borne. Symptoms of bacterial blight include small, irregular, chlorotic areas on leaves that can manifest into water-soaked, necrotic lesions. Lesions can also occur on stems and petioles. Floral infections can result in blighted umbels, reduced seed yield, and reduced germination rates of harvested seed. Once established, Xhc is difficult to control and disease prevention is challenging because Xhc is seedborne and seed treatments with hot water or disinfectants may not entirely eradicate the pathogen. The seed-borne nature of Xhc makes it a major concern not only to the hybrid carrot seed industry in the Pacific Northwest but also to regions that import carrot seed for root production. Epiphytic populations can reach high levels on plants in the field, resulting in seed that is infected or infested by the pathogen. Seed lots that are highly infested with Xhc (>105 CFU/g seed) necessitate seed treatment to reduce the risk of bacterial blight occurring in commercial root crop production. Seed treatments are usually in the form of hot water treatment (52°C for 25 minutes) which can be effective but can reduce germination and/or shelf life of seed lots. Germination can be reduced further if seed lots need to be treated multiple times to reduce infestation levels below the 105 CFU/g threshold that was established for carrot seed planted in the Central Valley of California. Chemical seed treatments, which can remove bacterial pathogens that are borne on the seed surface, may provide alternative or additional methods for reducing Xhc in carrot seed lots. The objective of this project was to evaluate chemical disinfectants as seed treatments to reduce Xhc levels in carrot seed lots.
Series/Report number: 
COARC2016

Evaluation of Improved Control of Bacterial Blight of Carrot with Early Season Copper Bactericides, 2006-2007

Central Oregon Agricultural Research Center 2007 Annual Report
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Series/Report number: 
1084

Reduced Xanthomonas on Seed-to-Seed Carrot Plants and Harvested Seed Resulting from Early Season Pesticide Applications, 2005-2006

Central Oregon Agricultural Research Center 2006 Annual Report
Series/Report number: 
1072

Drip Irrigation on Commercial Seed Carrots in Central Oregon, 2005

Central Oregon Agricultural Research Center 2005 Annual Report
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Series/Report number: 
1066

Reduced Xanthomonas and Increased Seed Germination from seed carrots Crops Irrigated by Drip vs Sprinkler, 2004 and 2005

Central Oregon Agricultural Research Center 2005 Annual Report
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Series/Report number: 
1066

Efficacy of Copper and Chlorine Products for Control of Xanthomonas Campestris by Carotae on Carrots

Central Oregon Agricultural Research Center 2004 Annual Report
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Series/Report number: 
1060

Incidence of Xanthomonas Capestris PV Carotae on seed carrots Irrigated by Drip or Sprinkler in Central Oregon

Central Oregon Agricultural Research Center 2004 Annual Report
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Series/Report number: 
1060

Bacterial Blight of Carrot Seed Crops: Identification of Sources of Inoculum

Central Oregon Agricultural Research Center 2003 Annual Report
Series/Report number: 
1053
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