Scientific Opinion on the pest categorisation of Xanthomonas campestris pv. vesicatoria (Doidge) Dye

Abstract

The European Commission requested the EFSA Panel on Plant Health to perform the pest categorisation for Xanthomonas campestris pv. vesicatoria, which is the causal agent of bacterial spot of tomato and pepper. X. campestris pv. vesicatoria is not a single taxonomic entity, and four separate species have been described: X. vesicatoria, X. euvesicatoria, X. perforans and X. gardneri. These organisms can be accurately identified based on a range of discriminative methods. Detection methods are available for seeds. Among the four species described within X. campestris pv. vesicatoria, all except X. gardneri were reported to be present in the EU territory. The host plants (tomato and pepper) are cultivated throughout Europe and conditions are conducive to disease development in open fields in southern Europe and in greenhouses. The disease causes a range of symptoms on aerial parts of plants including fruits. Contaminated seeds and transplants are responsible for longdistance dissemination of the pathogen. Control is mainly based on prevention and exclusion. Extraction of seeds from fruit debris using fermentation and acid treatments and thermotherapy treatments were shown to be effective in reducing the bacterial load in seed lots. No methods and chemical control agents are available that effectively control xanthomonads in infected crops. Although no recent data are available on economic losses caused by these pathogens in the EU, the organisms are considered important bacterial pathogens of tomato and pepper. Infections resulting in up to 30 % losses have been reported. Xanthomonads causing bacterial spot of tomato and pepper meet all criteria defined in International Standard for Phytosanitary Measures (ISPM) 21 and they also meet all ISPM 11 criteria, although X. vesicatoria, X. euvesicatoria and X. perforans are present in the EU territory. After consideration of the evidence, the Panel reached the following conclusions:

Assessment of Black Rot in Oilseed Rape Grown under Climate Change Conditions Using Biochemical Methods and Computer Vision

“…Infected seeds are the main source of Xcc infection, although this bacterium can also live epi- and endophytically in volunteer plants, crop debris, and even soils. Xcc penetrates the plant cell wall through wounds and natural openings such as stomata, hydatodes, and lenticels, colonizing the mesophyll [ 42 , 43 , 44 ]. The infection becomes systemic when Xcc reaches the xylem, plugging it and preventing water and nutrients from reaching it.…”