bacterial blight

Characterizing the Incidence and Distribution of Bacterial Blight Infestation in Individual Carrot Seeds: Can One Bad Seed Spoil the Whole Seed Lot?

Series/Report number: 
COARC2016
Abstract: 
Bulk samples of carrot seed are tested for Xanthomonas hortorum pv. carotae (Xhc) using a seed wash dilution-plating protocol (Asma, 2005). In this protocol, three 10 gram samples of carrot seed, equivalent to three subsamples of 10,000 seeds each, are soaked in buffer and serial dilutions are plated onto a semi-selective medium that limits the growth of bacteria other than Xhc. Testing protocols for seed-borne pathogens usually assume that infested seeds are fairly uniform (i.e. they follow the normal “bell-shaped curve”) with regards to bacterial populations on individual seeds and that the assay will detect the average number of bacteria for infested seed present in the sample. However, several studies have shown that the number of bacteria found on individual seeds may vary widely and follow non-normal distributions (i.e. they do not follow the normal “bell-shaped curve”) (Dutta et al., 2013). If the distributions of Xhc among infested carrot seeds are non-normal, assay results from bulk samples could result in an inaccurate estimate of the true population number. For example, if a seed lot contains relatively few, highly infested seeds, the bulk seed lot assay will be highly influenced by the number of highly infested seeds that are in a particular sample. On the other hand, a seed wash assay may not detect any infested seeds if only a few seeds in a seed lot are actually infested. The objective of this research is to determine the incidence and level of Xhc infestation among individual seeds in infested carrot seed lots. It is anticipated that this information will be important to the Oregon carrot seed industry, since many countries and markets have a zero-tolerance policy for Xhc in carrot seed. The incidence and level of infestation on individual seeds could also influence inoculum thresholds that are required for the development of bacterial blight in carrot root production. A better understanding of seed infestation in carrot seed lots will enable carrot seed producers to improve the methods used to prevent, detect, and treat infested seeds prior to market.

Timing Effect of ManKocide Application on Bacterial Blight on Carrot Seed, 2008-2009

Central Oregon Agricultural Research Center 2009 Annual Report
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Series/Report number: 
09-09

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

Drip Irrigation on Commercial Seed Carrots and Onions in Central Oregon, 2003

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