Evaluation of factors determining distribution, impact, detection and characterization of fruit tree phytoplasmoses (APOPHYT)

• Forschungsstelle: BLW
• Projektnummer: 07.14_4
• Projekttitel Englisch: Evaluation of factors determining distribution, impact, detection and characterization of fruit tree phytoplasmoses (APOPHYT)

Schlüsselwörter (Deutsch)

European stone fruit yellows (ESFY), Aprikosen, Candidatus phytoplasma prunorum, Cacopsylla pruni, Quarantäneorganismus, Phytoplasmen bei Fruchtbäumen

Schlüsselwörter (Englisch)

European stone fruit yellows (ESFY), apricots, Candidatus phytoplasma prunorum, Cacopsylla pruni, quarantine organism, fruit tree phytoplasmoses

Schlüsselwörter (Französisch)

European stone fruit yellows (ESFY), abricots, Candidatus phytoplasma prunorum, Cacopsylla pruni, organisme de quarantaine, phytoplasmes des arbres fruitiers

Kurzbeschreibung (Deutsch)

European stone fruit yellows (ESFY) ist eine Krankheit, die Aprikosenanlagen befällt, und im Kanton Wallis dazu führt, dass jährlich 4% der Aprikosenbäume ersetzt werden müssen. Verursacht wird die Krankheit durch die Übertragung von Candidatus phytoplasma prunorum mit dem Vektor Cacopsylla pruni (Quarantäneorganismus) oder in Baumschulen. Eine direkte Bekämpfung ist nicht möglich. Indirekt kann die Krankheit mit Insektiziden bekämpft werden.
Im Rahmen der europäischen Forschungszusammenarbeit „Evaluation of factors determining distribution, impact, detection and characterization of fruit tree phytoplasmoses (APOPHYT)“ ist im vorliegenden Projekt vorgesehen, die Wirksamkeit folgender Strategien des ESFY-Managements zu überprüfen und auszuwerten:

1. Handel und Anpflanzen von gesunden Jungbäumen
2. Vektorregulierung mit dem Ziel der Populationsreduktion
3. Entwicklung von ESFY-robusten Aprikosensorten.

Kurzbeschreibung (Englisch)

Apricot orchards are highly infested with ESFY in Valais. A global, long term and efficient management of ESFY in Switzerland is urgently required. Beside removal of diseased trees (about 4% of the trees per year), the management of ESFY is to be based on three main strategies:

1. first the trading and planting of healthy material
2. second the control of the vector and the reduction of its density
3. and third the development of low susceptible apricot varieties.

The objective of this study is to test and evaluate the effectiveness of these strategies.

This project fulfils the objectives of the EUPHRESCO project APOPHYT concerning ESFY and apricots and is an integral component of WP2, WP4 and WP6. Several APOPHYT partners will benefit from this project’s results.

Methoden (Englisch)

Task 1: Assessment of the level of latent infection of ESFY, AP and PD in propagation stocks, nurseries and in imported plant material and anastomosis (Lead: M. Bünter)
Root samples from apple, pear and apricot trees in Swiss propagation stocks and nurseries will be collected in autumn/winter for DNA extraction. In parallel, roots of 100 imported apricot trees will also be sampled for DNA extraction. The transmission of Ca. P. prunorum by anastomosis will be tested under confined conditions. Phytoplasma detection will be performed by standard PCR procedures. Additionally, the presence of different ESFY haplotypes in Switzerland will be monitored using sequencing procedures (in collaboration with INRA Montpellier).

Task 2: Evaluation of the C. pruni population density on various apricot cultivars, control of the population density of C. pruni using kaolin clay, and evaluation of the occurrence of the second psyllid vector (Lead: M. Genini, in collaboration INRA Montpellier)
The presence of psyllid species on 100 apricot varieties will be monitored by sweeping techniques and compared with potential symptom developments. Cacopsylla will be captured and the species will be identified. P. spinosa and 2-3 apricot varieties exhibiting a high C. pruni population density will be treated in field with kaolin clay at the beginning of each growing season. The putative diminution of C. pruni density on the treated trees will be assessed and the detection of Phytoplasma on the roots will be performed by standard PCR procedures.

Task 3: Assessment of the influence of Prunus genotypes on the migration behavior and on the ovipositional and feeding preferences of C. pruni (Lead: D. Christen)
Annual breeding of C. pruni will be established. The attractiveness of different Prunus spp., included apricot cultivars, will be assessed using a multiple choice arena (in collaboration with OCA-VS). The presence and amount of C. pruni on the different Prunus will be counted in order to assess the migration behaviour as well as the oviposition and feeding preferences of this vector. After a first general screening, plants exhibiting no attractiveness or very high attractiveness will be chosen and the differences of plant volatile emissions will be measured using an electronic nose. Furthermore, morphological plant characteristics will be observed in order to reveal antixenosis and antibiosis effects.

Projektziele (Englisch)

At the moment, the strategy to control ESFY infections in Switzerland is the removal of diseased trees. However this strategy is expensive and not efficient enough. The main objective of this study is to assess three alternative strategies to manage ESFY in Switzerland on the long term and in an efficient way.

1. First strategy is based on the trading and planting of healthy material (Task 1) Studies will be conducted to assess the level of latent infection of ESFY, AP and PD in propagation stocks, nurseries and in imported apricot trees and to evaluate the putative transmission of Ca. p. prunorum by anastomosis in nurseries.
2. Second strategy is based on the control of the vector and the reduction of its density (Task 2) Studies will be conducted to evaluate C. pruni population density on 100 apricot cultivars, to evaluate the effectiveness of alternative insecticides to reduce population density of C. pruni and to evaluate the occurrence and distribution of the second ESFY psyllid vector.
3. Third strategy is based on the development of low susceptible apricot varieties (Task 3) Studies will be conducted to evaluate the influence of Prunus genotypes on the migration behavior and the preferences of C. pruni.

Publikationen / Ergebnisse (Englisch)

Zugehörige Dokumente

• Final Report APOPHYT [PDF] 719 kB