First Record of Crown and Root Rot Caused by Cylindrocladium pauciramosum on Brush Cherry in Italy
Authors: Polizzi G. , Vitale A. , Aiello D. , Castello I. , Guarnaccia V. , Parlavecchio G. 
Published: April 2009

Brush cherry (Eugenia myrtifolia Sims; synonym Syzygium paniculatum Gaertn.) is a woody evergreen ornamental plant belonging to the Myrtaceae family. This plant is a very common species in Sicilian landscapes. In June of 2008, a new blight disease was detected in a commercial nursery located in Sicily (Italy) in a stock of 10,000 2-year-old E. myrtifolia cv. Newport potted plants obtained from cuttings. The disease was randomly distributed, affecting approximately 2% of the plants. Twig dieback, followed in some cases by plant death, was associated with crown and root rot. Roots were necrotic and crown tissue was brown. A Cylindrocladium sp. was consistently isolated from symptomatic roots, crowns, and lower stems of affected plants on potato dextrose agar petri dishes. Phytophthora isolates were not found associated with symptomatic tissues with BNPRAH (benomyl, nystatin, pentachloronitrobenzene, rifampicin, ampicillin, and hymexazol) selective medium. Five Cylindrocladium isolates were selected and subsequently identified as single-conidial colonies on carnation leaf agar. Isolates were incubated at 25°C under near-UV light with a 12-h_light/dark regimen and examined after 7 days (1). Isolates were characterized by having conidiophores terminating in obpyriform to broadly ellipsoidal vesicles and conidia hyaline, one septate, and straight with rounded ends, (50-) 54 to 55 (-59) × (3.5-) 4 to 6 μm. These characteristics, as well as their ability to produce perithecia when mated with Italian tester strains of Cylindrocladium pauciramosum, allowed their identification as C. pauciramosum C.L. Schoch & Crous (1,4). One mating type (MAT1-1) was found to be present on this host and a representative fungal isolate (DISTEF-Em3) was deposited at the Centraalbureau voor Schimmelcultures (CBS) open fungi collection (Fungal Biodiversity Centre, Utrecht, NL) with Accession No. 123917. Pathogenicity of the isolate DISTEF-Em3 was confirmed by applying 10 ml of a spore suspension (105 conidia per ml) to the crowns of 20 potted 4-month-old E. myrtifolia cv. Newport cuttings that were subsequently maintained in a greenhouse (23 to 25°C and 80 to 90% relative humidity). The same number of untreated plants was used as control. After 4 weeks, only four treated plants developed symptoms identical to those observed in the nursery. Control plants remained symptomless. C. pauciramosum was always reisolated from the infected plants and the identification of the isolate was made as previously described. Pathogenicity tests were repeated twice. In Italy, C. pauciramosum is a widespread pathogen in nurseries that causes extensive losses on young ornamental plants belonging to several genera (2,3). On the basis of the limited spread of the disease in the nursery and the pathogenicity tests, we consider Cylindrocladium crown and root rot of brush berry as a minor disease. However, this work demonstrated the susceptibility of brush cherry to C. pauciramosum that could lead to more extensive losses in association with other biotic or abiotic stresses. To our knowledge, this is the first record of crown and root rot caused by C. pauciramosum on brush cherry.

References: (1) P. W. Crous. Taxonomy and Pathology of Cylindrocladium (Calonectria) and Allied Genera. The American Phytopathological Society, St. Paul, MN, 2002. (2) G. Polizzi et al. Plant Dis. 85:803, 2001. (3) G. Polizzi et al. Plant Dis. 90:1459, 2006. (4) C. L. Schoch et al. Plant Dis. 85:941, 2001.