Citrus canker - Xanthomonas axonopodis pv. citri
EEffective: August 18, 2010 - December 31, 2011
Resources:
Pest Tracker
Screening Aids:
Taxonomic Position:
Xanthomonadales : Xanthomonadaceae
Pest Type:
Bacteria
Pest Code (NAPIS):
FDZAXAN
| No manual – See Host Matrix |
These Approved Methods are appropriate for:
Pest is vectored by:
Associated with: Citrus Leafminer (Phyllocnistis citrella)
Survey
Approved Method(s):
| Method | Instructions | NAPIS Survey Method |
|---|---|---|
| Visual | Collect symptomatic leaf and twig samples. |
3031 - General Visual Observation |
Signs:
No specific signs are present.
Symptoms:
Target younger growth that is in the last half of the expansion phase; look for blister-like, corky, tan to brown lesions with a water-soaked margin surrounded by a chlorotic halo on leaves, twigs, and fruit; abnormal leaf fall; blemished fruits that fall prematurely.
Key Diagnostics
ID/Diagnostic: Multiple
1. Serological using ELISA, 2. Culture, and 3. Molecular.
Causal agent must be confirmed by PCR. A PPQ-CPHST validated real-time PCR assay is available upon request as a work instruction for this diagnostic (Mavrodieva et al., 2004).
Preliminary screening should include: Water mount for indication of bacterial streaming.
A lactophenol cotton blue thin section may be useful, but caution is urged because Colletotrichum gloeosporioides and Alternaria spot are easily confused for citrus canker without molecular tools.
Mistaken Identities:
Colletotrichum gloeosporioides, Alternaria alternata, citrus leprosis virus, and X. citri pv. citrumelo.
In Progress / Literature-based Diagnostics:
Hartung et al. (1993) developed PCR for detection of Xanthomonas axonopodis pv. citri (Xac) A strain.
Hartung et al. (1996) developed immunocapture-nested PCR for detection of Xac A strain.
Cubrero et al. (2001) developed a quantitative PCR to diagnose Xac.
Cubrero and Graham (2002) developed conventional PCR for detection of all known X. axonopodis strains causing disease in citrus.
Cubrero and Graham (2005) developed a quantitative real-time PCR reaction to detect and differentiate Xac and X. axonopodis pv. citrumelo, the causal agent of bacterial spot.
Coletta-Filho et al. (2006) developed primers based on the rpf gene to detect Xac from naturally and artificially infected citrus plants.
Notes:
Both the pathogen and the vector are present in the United States.
Immunostrip: CPHST is currently validating a strip that can be used for field survey. The strip has been shown to work well on fruit; however, on plants, other Xanthomonas species may show a positive result as well.
Contact Renee DeVries for the most up-to-date work instructions.
Immunostrip: CPHST is currently validating a strip that can be used for field survey. The strip has been shown to work well on fruit; however, on plants, other Xanthomonas species may show a positive result as well.
Contact Renee DeVries for the most up-to-date work instructions.
References
- Coletta-Filho, H.D., Takita, M.A., de Souza, A.A., Neto, J.R., Desefano, S.A.L., Hartung, J.S., and Machado, M.A. 2006. Primers based on the rpf gene region provide improved detection of Xanthomonas axonopodis pv. citri in naturally and artificially infected citrus plants. Journal of Applied Microbiology 100: 279-285.
- Cubrero, J., and Graham, J.H. 2002. Genetic relationship among worldwide strains of Xanthomonas causing canker in citrus species and design of new primers for their identification by PCR. Appl. Environ. Microbiol. 68: 1257-1264.
- Cubrero, J., and Graham, J.H. 2005. Quantitative real-timer polymerase chain reaction for bacterial enumeration and allelic discrimination to differentiate Xanthamonas strains on citrus. Phytopathology 95: 1333-1340.
- Cubrero, J., Graham, J.H., and Gottwald, T.R. 2001. Quantitative PCR method for diagnosis of citrus bacterial canker. Appl. Environ. Microbiol. 67:2849-2852.
- Hartung, J.S., Daniel, J.F., and Pruvost, O.P. 1993. Detection of Xanthomonas campestris pv. citri by the polymerase chain reaction method. Appl. Environ. Microbiol. 59: 1143-1148.
- Hartung, J.S., Pruvost, O.P., Villemont, I., and Alvarez, A. 1996. Rapid and sensitive colorimetric detection of Xanthomonas axonopodis pv. citri by immunocapture and nested-polymerase chain reaction assay. Phytopathology 86: 95-101.
- Mavrodieva, V., Levy, L., and Gabriel, D. W. 2004. Improved sampling methods for real-time polymerase chain reaction diagnosis of citrus canker from field samples. Phytopathology 94:61-68. This paper is for real-time PCR on R.A.P.I.D. instruments. The assay was adapted to the Cepheid SmartCycler instrument and protocol is available.