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Poster: Biology & Disease Mgmt: Mycology


Virulence of Botrytis prunorum associated with blossom blight on Japanese plum in Chile
E. FERRADA (1), B. Latorre (1), J. Zoffoli (1), G. Diaz (2) (1) Pontificia Universidad Católica de Chile, Chile; (2) Universidad de Talca, Chile

Blossom Blight (BB) is an important disease that affects the productivity of stone fruits. Recently, B. prunorum was identified causing BB on Japanese plum (Prunus salicina) in Chile. Symptoms consisted on a light brown necrosis of flowers. The objective of this study was to compare the virulence exhibited by isolates B. prunorum and isolates of B. cinerea affecting plums. Virulence tests were conducted with seven isolates of B. prunorum on detached plum flowers and mature fruits ‘Larry Ann’ inoculated with a conidial suspension (106 conidia/mL) and mycelial plugs (4 mm in diameter). Mature fruits of ‘Granny Smith’ apples and ‘Hayward’ kiwifruits were similarly inoculated. Flowers and fruits were incubated for at least 48 h at 20°C in humid chambers. Seven B. cinerea isolates were included in all virulence tests. In addition, the virulence of B. prunorum and B. cinerea was studied on detached bean leaves that were inoculated with a mycelial plug (4 mm) incubated for 4 d at 20°C in humid chambers. All isolates of B. prunorum and B. cinerea were pathogenic on flowers and fruits of plums as well as on apple and kiwifruit and bean leaf. All isolates of B. prunorum were significantly (P<0.001) less virulent than B. cinerea isolates. Differences in virulence between B. cinerea and B. prunorum can be attributed to differences in the genetic expression of virulence factors. These results suggest that B. prunorum plays a secondary role in the epidemiology of BB of plums