Occurrence of privet anthracnose in Hungary caused by Glomerella cingulata

In Hungary, privet (Ligustrum vulgare L.) and its cultivars are widely planted and popular ornamental plants. Until 1999, there were no records of any important diseases of privet in Hungary. In 1999, a canker disease was observed in the south-eastern part of Hungary causing severe losses of mother plants and rooted cuttings of some cultivars of L. vulgare. Frequency of disease occurrence ranged between 30 - 40 % of cv. 'Lodense', 10 - 20 % of 'Chlorocarpum', and 10 % of 'Pyramidale'; only slight symptoms developed on cv. 'Atrovirens'. Ten - 60 % of infected mother plants of the different cultivars died. The highest loss occurred among mother plants of cv. 'Lodense'.

On infected stems and twigs typical symptoms of anthracnose appeared: several sunken lesions of 0.5 - 2.5 cm developed with pinkish, acervular type fruiting structures. Affected bark on the cankers split, exposing the wood. Plants died when twigs or stems were girdled. Dried-out leaves clung to such stems and twigs. The cause of cankers was identified as Glomerella cingulata (Stonem.) Spauld. et Schrenk, anamorph: Colletotrichum gloeosporioides (Penz.) Penz. et Sacc. Development of both the anamorph and teleomorph stage (acervuli and ascocarps) was common in diseased, dead bark tissue. Conidia measured 15.7 x 5.1 μm (13.0 - 22.5 x 4.5 - 5.5 µm).

Pathogenicity of the fungus was confirmed with a monoconidial culture on two-year-old potted privet plants of cvs. 'Lodense, 'Chlorocarpum', 'Pyramidale' and L. obtusifolium. Test plants, propagated from cuttings, were obtained from a nursery and kept during the test under greenhouse conditions at 15 - 28°C and 80% relative humidity. Six plants of each cv. and L. obtusifolium were inoculated with the fungus and three served as wounded uninoculated controls. This test was run twice. Because of the small size of test plants only one wound inoculation was made on each one, using mycelial agar plugs. After 14 days, sunken necrotic lesions with a brownish discoloration, similar to naturally occurring cankers, developed on inoculated plants. The most intensive stem canker development was observed on plants of cv. 'Lodense'. There was no infection on L. obtusifolium. Glomerella cingulata was successfully reisolated from the lesions of inoculated plants. After 6 weeks many stems died after cankers completely girdled them. No necrosis developed around control wounds. This is the first report of the occurrence of privet anthracnose in Hungary. This disease was reported recently from Poland (Orlikowski & Wojdyla, 1991) and is recorded from the Ukraine (Zerov, 1971) and several states in the US (Farr et al., 1989).