First report of Volutella pachysandricola on Pachysandra terminalis in the Czech Republic

Japanese pachysandra (P. terminalis) is a ground cover, woody ornamental plant, which is commonly found in parks and gardens of the Czech Republic. In 2002, disease symptoms were observed on Japanese pachysandra (P. terminalis 'Green Carpet' and P. terminalis 'Variegata') in Brno. The infected leaves showed tan or brown blotches with brown margins, which expanded, often with concentric zones (Fig. 1). Stem and stolon cankers appeared as water-soaked areas, turned brown, shrivelled and often girdled the stem (Fig. 2).

The infection often began in damaged or senescent plant parts and spread into the healthy parts of the plants. On newly killed stems and leaves, sporodochia-bearing pink spores (Fig. 3) were formed in high humidity during spring and summer periods. On the same tissue red-orange perithecia producing ascospores were formed. A fungus was isolated from the leaf lesions and stem and stolon cankers. On potato dextrose agar (PDA), the mycelium was sparse and aerial near the margin of the colony, completely immersed towards the centre when grown at 24°C. The colony surface was salmon coloured and slimy. Conidia were long and ellipsoid with rounded ends, measuring 10-21 x 3-4.1 μm. Morphological growth characteristics were consistent with the description of V. pachysandricola (Dodge, 1944).

Leaves of cuttings and wounded older stems of P. terminalis 'Green Carpet' were inoculated with a conidial suspension (1 x 10⁶ conidia per ml) of the isolated V. pachysandricola. Sterilised distilled water was applied to the control plants. Plants were covered with polyethylene bags during the entire incubation period to maintain high humidity and were kept at a temperature of 20-24°C. Typical disease symptoms appeared on leaves 5-9 days after infection. Sporodochia appeared after 6-8 days and plants were girdled after 2 weeks. Control plants were symptomless. Volutella pachysandricola was successfully reisolated from the lesions of inoculated plants, thus fullfilling Koch's postulates.

Volutella leaf blight and stem canker caused by the fungus Volutella pachysandricola (teleomorph Pseudonectria pachysandricola) is a serious disease previously recorded in the USA (Dodge, 1944, Rossmann, 1993), Britain (Sinclair et al., 1985), Germany (Nennmann, 2001) and Poland (Labanowski et al., 2000). This is the first record of this disease in the Czech Republic.