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Poster: Biology & Disease Mgmt: Genetics of Resistance


Susceptibility of Buxus accessions to the boxwood blight pathogen Calonectria pseudonaviculata
J. LAMONDIA (1) (1) The Connecticut Agricultural Experiment Station, U.S.A.

Forty Buxus accessions from the National Boxwood Collection of the U.S. National Arboretum provided as potted plants were evaluated for susceptibility to boxwood blight caused by Calonectria pseudonaviculata (Cps). Two experiments were conducted with 3 to 5 replicate plants each. Plants were inoculated with 1.5×105 Cps conidia in 2 ml coarse spray per plant and grown under high humidity with overhead irrigation. Leaf and stem lesions were recorded 3 or 4 wks after inoculation. B. harlandii (1 accession), B. sinica (3), B. microphylla (7) and B. bodinieri (1) had fewer lesions per plant than B. microphylla × sempervirens (6), which had fewer lesions than B. sempervirens (20 accessions). B. wallichiana (1 accession) was the most susceptible species (>160 lesions). Variation within species was also observed. B. sinica var. aemulans (accession 60705*H), B. sempervirens (36365*J) and B. harlandii (18834*H) were the least susceptible with < 10 lesions per plant. B. sempervirens ‘Scupi’ (9548*H), B. microphylla ‘Compacta’ (4899*CH), B. sempervirens 'Arborescens' (57953*H), B. sinica var. insularis 'Pincushion' (51898*H) and B. microphylla var. japonica 'Jim Stauffer' (72213*H) each had < 20 lesions. These data differ from previous detached leaf and unrooted cutting assays. Plant size may affect inoculation and disease, normalizing did not result in significant differences in susceptibility ranking. These results may aid in the development of boxwood resistance to Cps.