HomePlant DiseaseVol. 100, No. 7First Report of Volutella Blight caused by Pseudonectria buxi on Japanese Boxwood (Buxus microphylla) in Italy PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Volutella Blight caused by Pseudonectria buxi on Japanese Boxwood (Buxus microphylla) in ItalyA. Garibaldi, D. Bertetti, G. Ortu, and M. L. GullinoA. GaribaldiSearch for more papers by this author, D. BertettiSearch for more papers by this author, G. OrtuSearch for more papers by this author, and M. L. GullinoSearch for more papers by this authorAffiliationsAuthors and Affiliations A. Garibaldi D. Bertetti G. Ortu M. L. Gullino , Centre of Competence for the Innovation in the Agro-Environmental Sector (AGROINNOVA), 10095 Grugliasco, Italy. Published Online:31 Mar 2016https://doi.org/10.1094/PDIS-09-15-1027-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Buxus microphylla (Japanese boxwood) is a perennial shrub belonging to the Buxaceae family used for hedges in many parks and gardens. Starting June 2015, symptoms of a previously unknown blight were observed in a private garden located near Settime (Asti Province, northern Italy) on about 10% of 60 plants of B. microphylla. Affected plants were clustered. Symptoms started from twigs of the basal and central canopy, then spread to all foliage. Twigs displayed black streaking starting from the apex and showed dieback. Initially, leaves appeared chlorotic, later turned bronze, and then withered, becoming straw colored. Eventually, leaves died and dropped. Although plants did not die, their ornamental value was reduced. Light rose-colored sporodochia (97.1 to 274.2, avg. 185.6 µm) with setae, containing unicellular, elliptical conidia measuring 8.7 to 14.0 × 1.9 to 3.5 (avg. 10.9 × 2.9) µm, were observed on the abaxial leaf surface. Diseased stem tissue was excised from affected twigs, immersed in a solution of 1% sodium hypochlorite for 30 s, rinsed in sterilized water, cultured on potato dextrose agar (PDA) medium, and incubated at 25°C ± 1. Fungal colonies with white mycelium that turned pink-orange and produced verticillate conidiophores with unicellular, ovoid to elliptical conidia. Single-spore isolates were obtained. On PDA, conidia measured 3.6 to 6.5 × 1.8 to 3.5 (avg. 4.8 × 2.5) µm. Morphological features were typical of Pseudonectria buxi (Shi and Hsiang 2014a). The internal transcribed spacer (ITS) region of rDNA from a single-spore isolate (DB15GIU06M1) was amplified using the primers ITS1/ITS4, and sequenced. BLAST analysis (Altschul et al. 1997) of the 490-bp fragment (GenBank Accession No. KT736315) exhibited 100% similarity with JX535311, the sequence of Volutella buxi (syn. P. buxi). Beta-tubulin gene was also amplified (Shi and Hsiang 2014a). BLAST analysis of the 590-bp sequence (KU665623) exhibited 100% similarity with the sequence of V. buxi KC819609.1. Three-year-old healthy potted plants of B. microphylla were used to demonstrate Koch’s postulates. Leaves (10/plant) were cut about by half before the inoculation. Wounded leaves were inoculated by spraying (5 ml/plant) a spore suspension (1 × 108 CFU/ml) obtained from PDA cultures. Wounded leaves of control plants were inoculated with sterilized water. Plants (3 plants/treatment) were covered with plastic bags for 3 days and maintained in a growth chamber at 25° ± 1. Sporodochia developed on inoculated, wounded leaves 3 days after inoculation, followed by yellowing and browning of tissues. Pseudonectria buxi was consistently reisolated. Control plants remained healthy and reisolations attempted from wounded noninoculated leaves failed. The pathogenicity test was completed twice with the same results. This is the first report of P. buxi on B. microphylla in Italy. This pathogen has been reported on Buxus spp. such as B. sempervirens in several North American and European countries and more recently in China on B. sinica var. insularis (Shi and Hsiang 2014b). In Italy several species of Buxus are widely used in hedges in parks and gardens and the disease could also spread in nurseries, causing important economic losses such as those reported in Canada (Shi and Hsiang 2014a).