Quantification of Xanthomonas axonopodis pv. citri Populations in Citrus Groves
Population size, persistence, survival, and dispersal of Xanthomonas axonopodis pv. citri (Xac), the causal agent of citrus canker, are important factors in canker management in endemic regions. We quantified Xac populations on leaves and fruits of grapefruit (Citrus paradisi) , orange (C. sinensis) , and lemon (C. limon) trees, in rain water, in dew, and on weeds at different distances from cankerinfected citrus trees in Argentina. Viable bacterial cells were detected by infiltrating the sample liquid suspension in the mesophyll of Duncan grapefruit and Key lime (C. aurantifolia) seedlings kept in a growth room and the number of Xac was estimated by calibration with the number of canker lesions per square centimeter in an infectivity titration assay. Sampling was made during four consecutive growing seasons, from 2004 to 2008. Results indicated that high concentration of Xac (105 - 107) was recovered by external washing of 100％ of diseased fruits whereas 36％ of symptomless fruits carried Xac at 10 106 per fruit. Rain collected from diseased and symptomless leaves from an infected grove 100％ of the diseased ones carried populations from 102 -105 whereas 55％ -87％ of symptomless ones had 10 - 10 Xac cells per leaf. Dew collected from similar leaves and fruits had Xac in 100％ of them when they were diseased (10 - 104)and 77％ of the symptomless ones had 10 - 104 cells per ml. Weeds (mainly grass) were collected under the canopy and at 1, 5, 10, and 20 meters from diseased trees; samples positive for Xac decreased rapidly with distance from the infected grove. Positive samples were from 10 - 10 per gram of tissue. Dew, even when containing high Xac populations, apparently did not serve as a major inoculum source. Populations of Xac decreased sharply with increasing distances from the diseased trees even after rainstorms.
Citrus canker Ecology Epidemiology Dispersal Survival
B. I. Canteros M. A. Rybak L. Zequeira
Estacidn Experimental Agropecuaria Bella Vista INTA, Institute National de Tecnologia Agropecuaria, CCS, 3432Bella Vista, Corrientes
国际会议
11th International Citrus Congress(第11届国际柑橘大会)
武汉
英文
1030-1034
2008-10-01（万方平台首次上网日期，不代表论文的发表时间）