First Report of Brown Rot Caused by Monilinia fructicola on Various Stone and Pome Fruits in the Czech Republic.

Monilinia fructicola, a causal agent of brown rot, is one of the most important fungal pathogens of stone fruits. The disease causes major crop losses in peach, plum, prune, nectarine, and apricot. M. fructicola is commonly present in Asia, North and South America, and Australia. This is a quarantined pathogen in Europe; restricted occurrence has been observed in Austria and France. Recently, it was detected in Hungary and Switzerland on peach and nectarine fruits imported from Italy and Spain (1,4). During a survey in the summer of 2006, 56 samples were tested for the presence of Monilinia spp. M. fructicola was detected in 15 samples from 11 locations in the western area (Bohemia) of the Czech Republic, mainly on peaches (Prunus persica), apples (Malus × domestica), and sweet and sour cherries (Cerasus avium and C. vulgaris) and rarely on flowering plum (Prunus triloba) and Malus × moerlandsii cv. Liset. On the other hand, the pathogen was not detected on fruits of apricot (Prunus armeniaca) or pear (Pyrus communis). In all cases, M. fructicola was detected on fruits except for a single occurrence of the pathogen on a shoot of the Malus × domestica. The pathogen was always detected in mixed infections with M. fructigena and/or M. laxa. On both fruits and the shoot, symptoms appeared as brown, sunken lesions covered with grayish pustules. Many infected fruits became dry and mummified because rot progressed through the fruit surface. The infected shoot died back (3). M. fructicola was identified by means of colony and conidial morphology and molecular characteristics. The colonies cultivated on potato dextrose agar were entire and the colony surface was even. The color of the colony was gray, and sporulating colonies showed concentric rings that changed to a hazel color. Conidia were ellipsoid, hyaline, and 13.5 to 17.7 × 8.3 to 10.5 μm. Preliminary morphological identification was confirmed by PCR (2) on DNA isolated directly from mycelium on the examined fruits. A product that was 280 bp long was obtained in all cases. The BLAST analysis of our PCR product sequences showed 100% homology to sequences of M. fructicola (GenBank Accession Nos. DQ491506, AY2891185, Z73778, and AB125615). One sequence from our study was deposited in GenBank (Accession No. EF378628). To our knowledge, this is the first report of the quarantined fungus M. fructicola in the Czech Republic. References: (1) E. Bosshard et al. Plant Dis. 90:1554, 2006. (2) K. J. D. Hughes et al. EPPO Bull. 30:507, 2000. (3) J. M. Ogawa et al., eds. Compendium of Stone Fruit Diseases. The American Phytopathological Society, St. Paul, MN, 1995. (4) M. Petróczy and L. Palkovics. Plant Dis. 90:375, 2006.