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Source: European Plant Protection Organisation (EPPO) Reporting Service 02/2024/038 [summ. Mod.DHA, edited]

The NPPO [National Plant Protection Organisation] of Italy recently informed EPPO of the first finding of _Xylella fastidiosa_ subsp. _fastidiosa_ on its territory. The detection occurred outside the southern region currently demarcated for _X. fastidiosa_ subsp. _pauca_.

During the official surveys for _X. fastidiosa_ (EPPO A2 List) in Italy, a specimen of the vector _Philaenus spumarius_ tested positive for _X. fastidiosa_. To detect possibly infected plants, 432 host plant samples were taken. From these, 6 almond trees (_Prunus dulcis_) were found to be infected by _X. fastidiosa_ subsp. _fastidiosa_. A demarcated zone has been established, consisting of infected areas (50-m radius around each infected plant) and a buffer zone (2.5-km radius around the infected areas).
Communicated by:
[_Xylella fastidiosa_ (Xf) clogs the xylem of plants leading to wilting, necrosis and often death. It causes many serious crop diseases such as Pierce's disease of grapevine; leaf scorch of coffee, almond and olive; peach phony disease; plum leaf scald; citrus variegated chlorosis; lucerne dwarf; and leaf scorch of a range of other woody species. Latent infections of wild species as potential pathogen reservoirs have also been reported. A second species in the genus, _X. taiwanensis_, has recently been reported as the cause of a pear leaf scorch (see ProMED post 20181022.6105629).

Xf is spread by xylem-feeding insects, but also by grafting and with infected plant material. Moist conditions favour the vectors and therefore Xf-associated diseases. Disease management is difficult due to the large numbers of hosts and vectors and may include use of clean planting and grafting material, as well as vector control. Both the bacterium and its main vectors are of serious international quarantine concern. They are currently considered the most serious threat to European grape and fruit production.

Three subspecies have been formally accepted for Xf: _fastidiosa_ (grapevine strain, Pierce's disease), _pauca_ and _multiplex_, but additional ones have been proposed. It appears that subspecies vary in host range, but more research is needed on susceptibility of different plant hosts to the different Xf subspecies; multiple Xf subspecies have also been found to be able to infect the same host species (e.g., both _pauca_ and _multiplex_ can affect olives). The initial European detection in olives was of ssp. _pauca_ in southern Italy, but all 3 ssp. have since been found in different European areas in a range of hosts. More information is urgently needed on distribution, epidemiology and the risks to different crops by Xf or its subspecies.

Europe, overview:

Photo galleries of Xf symptoms & vectors, different hosts: and via
Xf on almond:, and
_P. spumarius_ vector: and

Additional news story (in Italian):
_X. fastidiosa_ diseases, diagnosis & vector information: (with distribution map),, and
Xf ssp _fastidiosa_ information & distribution:
Xf ssp _pauca_ information & distribution:
Xf strains and host range:,,, and
Xf resources and information via:
_X. fastidiosa_ taxonomy and strains:
EPPO A2 quarantine list:
Information on Xf vectors via:
- Mod.DHA


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