RESISTANCE OF SOME PYRUS COMMUNIS CULTIVARS AND PYRUS HYBRIDS TO THE PEAR PSYLLA CACOPSYLLA PYRI (HOMOPTERA, PSYLLIDAE)

Pear psylla is a very important problem in French pear orchards.
Resistant cultivars would offer an alternative to chemical control.
However all major cultivars grown in France are susceptible to Cacopsylla pyri. Some Pyrus inter-specific hybrids are known to be resistant to pear psylla; yet, the bad quality of the fruits limit the usefulness of these genotypes in breeding programs.
To identify other resistant genotypes, screening of 16 genotypes of Pyrus was conducted in a mesh-covered tunnel during 4,5 months.
The cultivar ‘Williams known’ to be sensitive to pear psylla, was considered as susceptible control.
The hybrids ‘Katman’ and ‘NY10355’ were considered as resistant controls.
The observations were carried out on 7 or 8 plants per genotype.
The eggs were recorded on the eight upper leaves of the shoots 15 days after the release of adults in the tunnel.
The nymphs were recorded on the eight upper leaves of the shoots, 36, 63 and 98 days after infestation.
The shoot and the leaf states were recorded after 134 days.
Several inter-specific hybrids (‘BP6’, ‘BP81’, ‘Gutui’ and ‘P20R5A70’) were identified as highly resistant.
Our results confirm also the resistance of ‘Spina Carpi’, an old Italian cultivar.
Furthermore, three P. communis were newly identified as resistant: the ‘Doyenné de Poitiers’, the ‘D’Août Lamer’and the hybrid ‘SEL80-79-69’ (‘Docteur Jules Guyot’ × ‘Bella di Giugno’). However, these genotypes exhibited medium levels of resistance to pear psylla.

IX International Pear Symposium

P. Robert, T. Raimbault

damage, egg, nymph, Pyrus serotina, Pyrus ussuriensis, screening, susceptible

https://doi.org/10.17660/ActaHortic.2005.671.80