| Legend |
|---|
| Justification for qualification based on EPPO PM 4 Standards |
| Justification for disqualification |
| Additional or non-conclusive information |
| Standard text |
NAME OF THE ORGANISM: Cranberry false blossom phytoplasma (PHYPFB)
GENERAL INFORMATION ON THE PEST
Name as submitted in the project specification (if different):
Pest category:
Bacteria
1- Identity of the pest/Level of taxonomic listing:
Is the organism clearly a single taxonomic entity and can it be adequately distinguished from other entities of the same rank?
Yes
Is the pest defined at the species level or lower?:
Yes
Can listing of the pest at a taxonomic level higher than species be supported by scientific reasons or can species be identified within the taxonomic rank which are the (main) pests of concern?
- Not relevant: Fruits (including hops) sector
If necessary, please list the species:
-
Is it justified that the pest is listed at a taxonomic rank below species level?
Not relevant
Conclusion:
- Null: Fruits (including hops) sector
Justification (if necessary):
Remark: Instead of listing Blueberry witches' broom phytoplasma, during the RNQP Project part 1, the Fruit SEWG proposed to discard all names of phytoplasma listed in the EU Marketing Directive and to add all phytoplasma species reported from naturally infected Vaccinium plants (‘Candidatus Phytoplasma pruni’, ‘Candidatus Phytoplasma asteris’ [Blueberry stunt phytoplasma], ‘Candidatus Phytoplasma solani’ [Blueberry Reddening disease], and the Cranberry false blossom phytoplasma). ‘Candidatus Phytoplasma asteris’ was listed in the revised Marketing Directive.
In the RNQP Project part 2, although a specific assessment of the RNQP status is made for cranberry false blossom phytoplasma, it is also addressed under ‘Candidatus Phytoplasma pruni’ / ‘Ca. P. pruni’-related strains.
The American strains (known as cranberry false blossom disease, CFBD) are probably different from the European strains (known as witches’ broom), but all belong to ‘Candidatus Phytoplasma pruni’ or ‘Ca P. pruni’ related strains / 16SrIII group / X-disease group. The phytoplasma responsible for CFBD can also cause witches’ broom symptoms. In North America the vectors are mostly known, in Europe the vectors are not known / not reported – probably due to the rarity of phytoplasma disease in commercial Vaccinium spp.
The cranberry false blossom disease (CFBD), caused by a phytoplasma from subgroup 16SrIII-Y (Lee et al. 2014), affects the American cranberry (Vaccinium macrocarpon) and is vectored by the blunt-nosed leafhopper Limotettix vaccinii (Beckwith & Hutton, 1929; in Almeida Santos et al., 2023; Chen & Polashock, 2017). CFBD-infected plants exhibit symptoms like witches’ broom-shaped shoots, early reddening leaves, and malformed flowers with distinct discoloration, leading to failed fruit setting (Pradit et al. 2019). From 1920 to 1930, CFBD severely threatened cranberry production in New Jersey, USA, almost collapsing the industry (Beckwith & Hutton 1929; in Almeida Santos et al., 2023). Control measures, including insecticides, removing infected plants, and introducing less vector-attractive cultivars, eventually reduced the disease’s prevalence. However, recent reports indicate its resurgent occurrence on many cranberry farms in New Jersey, USA, where another leafhopper species, Scaphytopius magdalensis , previously identified as a blueberry stunt phytoplasma vector, was positive for the CFBD phytoplasma, although no transmission assay was performed (Lee et al. 2014). This indicates that S. magdalensis could also be a CFBD phytoplasma vector in North America (Almeida Santos et al., 2023).
In the RNQP Project part 2, although a specific assessment of the RNQP status is made for cranberry false blossom phytoplasma, it is also addressed under ‘Candidatus Phytoplasma pruni’ / ‘Ca. P. pruni’-related strains.
The American strains (known as cranberry false blossom disease, CFBD) are probably different from the European strains (known as witches’ broom), but all belong to ‘Candidatus Phytoplasma pruni’ or ‘Ca P. pruni’ related strains / 16SrIII group / X-disease group. The phytoplasma responsible for CFBD can also cause witches’ broom symptoms. In North America the vectors are mostly known, in Europe the vectors are not known / not reported – probably due to the rarity of phytoplasma disease in commercial Vaccinium spp.
The cranberry false blossom disease (CFBD), caused by a phytoplasma from subgroup 16SrIII-Y (Lee et al. 2014), affects the American cranberry (Vaccinium macrocarpon) and is vectored by the blunt-nosed leafhopper Limotettix vaccinii (Beckwith & Hutton, 1929; in Almeida Santos et al., 2023; Chen & Polashock, 2017). CFBD-infected plants exhibit symptoms like witches’ broom-shaped shoots, early reddening leaves, and malformed flowers with distinct discoloration, leading to failed fruit setting (Pradit et al. 2019). From 1920 to 1930, CFBD severely threatened cranberry production in New Jersey, USA, almost collapsing the industry (Beckwith & Hutton 1929; in Almeida Santos et al., 2023). Control measures, including insecticides, removing infected plants, and introducing less vector-attractive cultivars, eventually reduced the disease’s prevalence. However, recent reports indicate its resurgent occurrence on many cranberry farms in New Jersey, USA, where another leafhopper species, Scaphytopius magdalensis , previously identified as a blueberry stunt phytoplasma vector, was positive for the CFBD phytoplasma, although no transmission assay was performed (Lee et al. 2014). This indicates that S. magdalensis could also be a CFBD phytoplasma vector in North America (Almeida Santos et al., 2023).
2 – Status in the EU:
Is this pest already a quarantine pest for the whole EU?
No
Presence in the EU:
No
List of countries (EPPO Global Database):
-
Conclusion:
Not candidate
Justification (if necessary):
Cranberry false blossom disease (16SrIII-Y USA, Canada, Lee et al., 2014) also belongs to the ‘Ca. Phytoplasma pruni’ group & related strains. However, it has not been reported from the EU yet. Remark: presence in the EU depends on species definition: Ca. P. pruni (-related) or seperate species.
HOST PLANT N°1: Vaccinium (1VACG) for the Fruits (including hops) sector.
Origin of the listing:
Commission Implementing Directive (EU) 2014/98/EU and Commission Implementing Regulation (EU) 2019/2072
Plants for planting:
Plants intended for planting
3 - Is the pest already listed in a PM4 standard on the concerned host plant?
Yes
Conclusion:
Evaluation continues
Justification (if necessary):
Listed in EPPO Standard PM 4-18 Certification scheme for Vaccinium, which recommends testing for 'Cranberry false blossom phytoplasma'. However, when responding to the questionnaire, AT, NL, PL and SI supported deregulation in the EU: NL and SI questioned whether the phytoplasma was present in the EU. PL considered that plants for planting was not the main pathway. AT was in favour of listing all Phytoplasmas together (phytoplasma symptoms may not be differentiated and, 'likely, a laboratory test will be a universal phytoplasma test'). Evaluation continues with a full assessment.
4 - Are the listed plants for planting the main* pathway for the "pest/host/intended use" combination? (*: significant compared to others):
Conclusion:
Justification:
Cranberry false blossom disease belongs to the ‘Ca. Phytoplasma pruni’ group & related strains.
‘Ca. Phytoplasma pruni’ & related strains have a wide host range (EFSA, 2020; Siller et al., 1986; Lorenz et al., 1986; Seemüller et al., 1994, Valiunas et al., 2004; Jomantiene et al. 2002; Fernandez et al., 2017; Bertaccini & Dudek, 2009; Lee, 2000).
Cranberry false blossom disease (16SrIII-Y USA, Canada, Lee et al., 2014) is only reported from Vaccinium macrocarpon (cranberry) and V. oxycoccus.
It is vectored by the blunt-nosed leafhopper (Limotettix vaccinii, formely known as Scleroracus vaccinii, Euscellis striatulus) (Lee et al., 2014; Chen & Polashock, 2017). The leafhopper Scaphytopius magdalensis was also found positive for CFBD, which could indicate that this species might be also a vector, but no transmission experiments were carried out (Lee et al., 2014; Almeida Santos et al., 2023).
Phytoplasmas can travel with plant material, but as long as the vector is not occurring in the area, no field transmission is expected.
‘Ca. Phytoplasma pruni’ & related strains have a wide host range (EFSA, 2020; Siller et al., 1986; Lorenz et al., 1986; Seemüller et al., 1994, Valiunas et al., 2004; Jomantiene et al. 2002; Fernandez et al., 2017; Bertaccini & Dudek, 2009; Lee, 2000).
Cranberry false blossom disease (16SrIII-Y USA, Canada, Lee et al., 2014) is only reported from Vaccinium macrocarpon (cranberry) and V. oxycoccus.
It is vectored by the blunt-nosed leafhopper (Limotettix vaccinii, formely known as Scleroracus vaccinii, Euscellis striatulus) (Lee et al., 2014; Chen & Polashock, 2017). The leafhopper Scaphytopius magdalensis was also found positive for CFBD, which could indicate that this species might be also a vector, but no transmission experiments were carried out (Lee et al., 2014; Almeida Santos et al., 2023).
Phytoplasmas can travel with plant material, but as long as the vector is not occurring in the area, no field transmission is expected.
5 - Economic impact:
Are there documented reports of any economic impact on the host?
Yes
Justification:
Cranberry false blossom disease in the USA (16SrIII-Y), infected plants of American cranberry (Vaccinium macrocarpon) exhibit abnormal floral structure including enlarged calix, and shortened, discolored and streaked petals. In the first half o the 20th century the prevalence of cranberry false-blossom disease and an abundance of the vector (Limotettix vacinii) that transmitted the disease became a threat for the cranberry industry in the USA. Through collective efforts, varieties resistant to false-blossom disease were developed and reduced false blossom to an insignificant factor. However there appears to be a resurgence of the disease (Lee et al., 2014; Chen revised by Polashock, 2017).
What is the likely economic impact of the pest irrespective of its infestation source in the absence of phytosanitary measures? (= official measures)
Is the economic impact due to the presence of the pest on the named host plant for planting, acceptable to the propagation and end user sectors concerned?
Is there unacceptable economic impact caused to other hosts (or the same host with a different intended use) produced at the same place of production due to the transfer of the pest from the named host plant for planting?
Conclusion:
Justification:
6 - Are there feasible and effective measures available to prevent the presence of the pest on the plants for planting at an incidence above a certain threshold (including zero) to avoid an unacceptable economic impact as regards the relevant host plants?
Conclusion:
Justification:
In the USA and Canada, the phytoplasma and its vector are already in the field, and propagation material is not a major pathway.
Late flooding has been shown to cause a higher mortality of plants with false blossom than of healthy plants and thus reduces inoculum sources. Flooding a bed in June, just before the flowers open and after the leafhopper eggs have hatched, has proved effective for leafhopper control, but timing is critical and vine damage is a distinct possibility (Chen revised by Polashock, 2017).
Cultivars which are reported to have field resistance, were found to be less attractive to the vector than were more susceptible cultivars (Chen revised by Polashock, 2017).
Late flooding has been shown to cause a higher mortality of plants with false blossom than of healthy plants and thus reduces inoculum sources. Flooding a bed in June, just before the flowers open and after the leafhopper eggs have hatched, has proved effective for leafhopper control, but timing is critical and vine damage is a distinct possibility (Chen revised by Polashock, 2017).
Cultivars which are reported to have field resistance, were found to be less attractive to the vector than were more susceptible cultivars (Chen revised by Polashock, 2017).
7- Is the quality of the data sufficient to recommend the pest to be listed as a RNQP?
Conclusion:
Justification:
CONCLUSION ON THE STATUS:
Disqualified: absent from the EU. Also covered by the RNQP summary sheet for 'Ca. P. pruni' (and related strains).
8 - Tolerance level:
Is there a need to change the Tolerance level:
Yes
Proposed Tolerance levels:
Delisting
9 - Risk management measures:
Is there a need to change the Risk management measure:
Yes
Proposed Risk management measure:
Delisting
REFERENCES:
- Almeida Santos A, Jacques J, Plante N, Fournier V & Perez-Lopez E (2023) Leafhoppers as vectors of phytoplasma diseases in Canadian berry crops: a review in the face of climate change. Annals of the Entomological Society of America 117(1), 14-20
- Beckwith CS & Hutton SB (1929) Cranberry false blossom and the blunt-nosed leafhopper. New Jersey Agricultural Experiment Station Bulletin 491, 1-16.
- Bertacchini A & Duduk B (2009) Phytoplasma and phytoplasma diseases: a review of recent research. Phytopathology Mediterranea 48, 355-378.
- Chen TA & Polashock, 2017. False blossom. In Compendium of blueberry, cranberry, and lingonberry diseases and pests 2nd edition (eds Polashock JJ, Caruso FL, Averill AL & Schilder AC). American Phytopathological Society, St. Paul, Minnesota, USA. pages 123-124.
- EFSA (2020) Pest categorisation of the non-EU phytoplasmas of Cydonia Mill., Fragaria L., Malus Mill., Prunus L., Pyrus L., Ribes L., Rubus L. and Vitis L. EFSA Journal 18(1):5929.
- Lee IM (2000) Phytoplasma casts a magic spell that turns the fair poinsettia into a Christmas showpiece. Online. Plant Health Progress doi:10.1094/PHP-2000-0914-01-RV.
- Lee IM, Gundersen-Rindal DE & Bertaccini A (1998) Phytoplasma: Ecology and genomic diversity. Phytopathology 88:1359-1366.
- Lee IM, Polashock J, Bottner-Parker KD, Bagadia PG, Rodriguez-Saona C, Zhao Y & Davis RE (2014) New subgroup 16SrIII-Y phytoplasmas associated with false-blossom diseased cranberry (Vaccinium macrocarpon) plants and with known and potential insect vectors in New Jersey. European Journal of Plant Pathology 139, 399–406. DOI 10.1007/s10658-014-0396-7.
- Seemüller E, Schneider B, Maurer R, Ahrens U, Daire X, Kison H, Lorenz KH, Firra G, Avinent L, Sears BB & Stackebrandt E (1994) Phylogenetic classification of phytopathogenic mollicutes by sequence analysis of 16S ribosomal DNA. International Journal of Systematic Bacteriology 44(3), 440-446.
- Siller W, Lederer W & Seemüller E (1986) Ursache und Verbreitung der Hexenbesenkrankheit der Heidelbeere ( Vaccinium myrtillus L.) in Waldgebieten Süddeutschlands. Nachrichtenblatt des Deutschen Pflanzenschutzdienstes 38 (1), S. 1-5.
- Valiunas D, Alminaite A, Jomantiene R, Davis RE & Maas JL (2004) Possible cause of European blueberry disease is related to North American milkweed yellows phytoplasma. Journal of Plant Pathology 86(2):135-140.