Seiridium cardinaleis a new threat to cypress trees in Cyprus

Abstract

Seiridium cardinale is a serious fungal pathogen of cypress trees, causing branch and trunk cankers. It is common in the Mediterranean region (Graniti, 1998) but has not been found in regular surveys in Cyprus, where Cupressus spp. are highly valued endemic trees and widely planted. In February 2007, bark necrosis and resin exudation on 10-year-old Cupressus macrocarpa‘Goldcrest’ was observed in a nursery in Lemesos (Limassol). Acervuli with characteristic conidia of S. cardinale were found and the fungus was isolated from necrotic bark tissues from three different plants. Colonies on potato dextrose agar (PDA) were dense, floccose, with grey aerial mycelium and radial growth rate of 10–12 mm per week on PDA at 25°C, similar to reference cultures of S. cardinale from Greece and Italy. Conidia were 5-septate, oblong-fusiform (20–29 × 8–10 µm), with characteristic hyaline, conical apical cells, about 1 µm long, again typical of S. cardinale. In March 2007, 3-year-old plants of C. sempervirens and C. macrocarpa were stem inoculated (Tsopelas et al., 2007) with isolate ATHUM 5661, deposited in the culture collection of the University of Athens. Stem cankers (3–4 cm long) developed on both species 3 months after inoculation. Acervuli of S. cardinale were present in some cases. Control plants inoculated with sterile agar plugs remained healthy. Seiridium cardinale was consistently re-isolated from infected plants. This is the first report of S. cardinale in Cyprus. Cypress trees were imported by the nursery from Italy, where the disease is widespread, several years ago but none were imported since. The diseased trees had advanced symptom development (branch dieing), suggesting that the pathogen was introduced on the imported trees. Trees with young cankers (bark necrosis) suggested spread within the nursery. There is a strong possibility that infected trees have been sold. Active surveillance of ornamental plantings is needed to prevent establishment of a damaging disease.